Complex
Primitive
ActivityDefinition
CapabilityStatement
CodeSystem
Composition
ConceptMap
Encounter
Library
List
Measure
MessageHeader
Observation
Patient
PlanDefinition
Questionnaire
Resource
ServiceDefinition
StructureDefinition
StructureMap
ValueSet
default
Base StructureDefinition for Observation Resource
Observation
Path
Observation
Id
Observation
Cardinality
0 - *
Definition
Measurements and simple assertions made about a patient, device or other subject.
Comment
Used for simple observations such as device measurements, laboratory atomic results, vital signs, height, weight, smoking status, comments, etc. Other resources are used to provide context for observations such as lab reports, etc.
Constraint
dom-2 [error]
If the resource is contained in another resource, it SHALL NOT contain nested Resources
dom-1 [error]
If the resource is contained in another resource, it SHALL NOT contain any narrative
dom-4 [error]
If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated
dom-3 [error]
If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource
obs-7 [error]
If code is the same as a component code then the value element associated with the code SHALL NOT be present
obs-6 [error]
dataAbsentReason SHALL only be present if Observation.value[x] is not present
Path
Observation.identifier
Id
Observation.identifier
Type
Cardinality
0 - *
Definition
A unique identifier assigned to this observation.
Comment
Requirements
Allows observations to be distinguished and referenced.
Path
Observation.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.identifier.Identifier.type.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.identifier.Identifier.assigner.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.basedOn
Id
Observation.basedOn
Type
Cardinality
0 - *
Definition
A plan, proposal or order that is fulfilled in whole or in part by this event.
Comment
Requirements
Allows tracing of authorization for the event and tracking whether proposals/recommendations were acted upon.
Path
Observation.basedOn.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.basedOn.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.basedOn.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.basedOn.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.basedOn.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.basedOn.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.basedOn.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.basedOn.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.basedOn.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.basedOn.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.basedOn.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.basedOn.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.basedOn.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.basedOn.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.basedOn.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.status
Id
Observation.status
Type
Cardinality
1 - 1
Definition
The status of the result value.
Comment
This element is labeled as a modifier because the status contains codes that mark the resource as not currently valid.
Requirements
Need to track the status of individual results. Some results are finalized before the whole report is finalized.
Path
Observation.category
Id
Observation.category
Type
Cardinality
0 - *
Definition
A code that classifies the general type of observation being made.
Comment
In addition to the required category valueset, this element allows various categorization schemes based on the owner’s definition of the category and effectively multiple categories can be used at once. The level of granularity is defined by the category concepts in the value set.
Requirements
Used for filtering what observations are retrieved and displayed.
Path
Observation.category.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.category.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.category.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.category.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.category.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.category.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.code
Id
Observation.code
Type
Cardinality
1 - 1
Definition
Describes what was observed. Sometimes this is called the observation "name".
Comment
Requirements
Knowing what kind of observation is being made is essential to understanding the observation.
Path
Observation.code.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.code.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.code.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.code.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.code.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.code.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.subject
Id
Observation.subject
Type
Cardinality
0 - 1
Definition
The patient, or group of patients, location, or device whose characteristics (direct or indirect) are described by the observation and into whose record the observation is placed. Comments: Indirect characteristics may be those of a specimen, fetus, donor, other observer (for example a relative or EMT), or any observation made about the subject.
Comment
One would expect this element to be a cardinality of 1..1. The only circumstance in which the subject can be missing is when the observation is made by a device that does not know the patient. In this case, the observation SHALL be matched to a patient through some context/channel matching technique, and at this point, the observation should be updated.
If the target of the observation is different than the subject, the general extension [observation-focal-subject](extension-observation-focal-subject.html). may be used. However, the distinction between the patient's own value for an observation versus that of the fetus, or the donor or blood product unit, etc., are often specified in the observation code.
Requirements
Observations have no value if you don't know who or what they're about.
Path
Observation.subject.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.subject.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.subject.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.subject.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.subject.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.subject.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.subject.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.subject.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.subject.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.subject.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.subject.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.subject.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.subject.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.subject.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.subject.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.context
Id
Observation.context
Type
Cardinality
0 - 1
Definition
The healthcare event (e.g. a patient and healthcare provider interaction) during which this observation is made.
Comment
This will typically be the encounter the event occurred within, but some events may be initiated prior to or after the official completion of an encounter or episode but still be tied to the context of the encounter or episode (e.g. pre-admission lab tests).
Requirements
For some observations it may be important to know the link between an observation and a particular encounter.
Path
Observation.context.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.context.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.context.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.context.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.context.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.context.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.context.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.context.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.context.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.context.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.context.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.context.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.context.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.context.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.context.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.effective[x]
Id
Observation.effective[x]
Type
Cardinality
0 - 1
Definition
The time or time-period the observed value is asserted as being true. For biological subjects - e.g. human patients - this is usually called the "physiologically relevant time". This is usually either the time of the procedure or of specimen collection, but very often the source of the date/time is not known, only the date/time itself.
Comment
At least a date should be present unless this observation is a historical report.
Requirements
Knowing when an observation was deemed true is important to its relevance as well as determining trends.
Path
Observation.issued
Id
Observation.issued
Type
Cardinality
0 - 1
Definition
The date and time this observation was made available to providers, typically after the results have been reviewed and verified.
Comment
Updated when the result is updated.
Path
Observation.performer
Id
Observation.performer
Type
Cardinality
0 - *
Definition
Who was responsible for asserting the observed value as "true".
Comment
Requirements
May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.
Path
Observation.performer.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.performer.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.performer.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.performer.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.performer.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.performer.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.performer.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.performer.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.performer.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.performer.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.performer.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.performer.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.performer.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.performer.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.performer.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.value[x]
Id
Observation.value[x]
Type
Cardinality
0 - 1
Definition
The information determined as a result of making the observation, if the information has a simple value.
Comment
Normally, an observation will have either a single value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. This element has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueString, valueBoolean, valueRange, valueRatio, valueSampledData, valueAttachment, valueTime, valueDateTime, or valuePeriod. (The name format is "'value' + the type name" with a capital on the first letter of the type).
If the data element is usually coded or if the type associated with the Observation.value defines a coded value, use CodeableConcept instead of string datatype even if the value is uncoded text. A value set is bound to the ValueCodeableConcept element. For further discussion and examples see the [notes section](observation.html#notes) below.
Requirements
An observation exists to have a value, though it may not if it is in error, or if it represents a group of observations.
Condition
obs-7
Path
Observation.value[x].Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.value[x].Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.value[x].Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.value[x].Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.value[x].Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.dataAbsentReason
Id
Observation.dataAbsentReason
Type
Cardinality
0 - 1
Definition
Provides a reason why the expected value in the element Observation.value[x] is missing.
Comment
Null or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "specimen unsatisfactory". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Note that an observation may only be reported if there are values to report. For example differential cell counts values may be reported only when > 0. Because of these options, use-case agreements are required to interpret general observations for null or exceptional values.
Requirements
For many results it is necessary to handle exceptional values in measurements.
Binding
Strength
extensible
Description
Codes specifying why the result (Observation.value[x]) is missing.
ValueSet
Condition
obs-6
Path
Observation.dataAbsentReason.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.dataAbsentReason.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.dataAbsentReason.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.dataAbsentReason.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.dataAbsentReason.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.dataAbsentReason.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.interpretation
Id
Observation.interpretation
Type
Cardinality
0 - 1
Definition
The assessment made based on the result of the observation. Intended as a simple compact code often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result. Otherwise known as abnormal flag.
Comment
Requirements
For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.
Path
Observation.interpretation.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.interpretation.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.interpretation.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.interpretation.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.interpretation.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.interpretation.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.comment
Id
Observation.comment
Type
Cardinality
0 - 1
Definition
May include statements about significant, unexpected or unreliable values, or information about the source of the value where this may be relevant to the interpretation of the result.
Comment
Requirements
Need to be able to provide free text additional information.
Path
Observation.bodySite
Id
Observation.bodySite
Type
Cardinality
0 - 1
Definition
Indicates the site on the subject's body where the observation was made (i.e. the target site).
Comment
Only used if not implicit in code found in Observation.code. In many systems, this may be represented as a related observation instead of an inline component. If the use case requires BodySite to be handled as a separate resource (e.g. to identify and track separately) then use the standard extension[ body-site-instance](extension-body-site-instance.html).
Path
Observation.bodySite.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.bodySite.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.bodySite.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.bodySite.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.bodySite.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.bodySite.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.method
Id
Observation.method
Type
Cardinality
0 - 1
Definition
Indicates the mechanism used to perform the observation.
Comment
Only used if not implicit in code for Observation.code.
Requirements
In some cases, method can impact results and is thus used for determining whether results can be compared or determining significance of results.
Path
Observation.method.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.method.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.method.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.method.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.method.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.method.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.specimen
Id
Observation.specimen
Type
Cardinality
0 - 1
Definition
The specimen that was used when this observation was made.
Comment
Should only be used if not implicit in code found in `Observation.code`. Observations are not made on specimens themselves; they are made on a subject, but in many cases by the means of a specimen. Note that although specimens are often involved, they are not always tracked and reported explicitly. Also note that observation resources may be used in contexts that track the specimen explicitly (e.g. Diagnostic Report).
Path
Observation.specimen.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.specimen.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.specimen.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.specimen.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.specimen.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.specimen.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.specimen.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.specimen.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.specimen.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.specimen.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.specimen.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.specimen.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.specimen.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.specimen.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.specimen.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.device
Id
Observation.device
Type
Cardinality
0 - 1
Definition
The device used to generate the observation data.
Comment
An extension should be used if further typing of the device is needed. Devices used to support obtaining an observation can be represented using either an extension or through the Observation.related element.
Path
Observation.device.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.device.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.device.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.device.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.device.Reference.identifier.Identifier.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.device.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.device.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.device.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.device.Reference.identifier.Identifier.period.Period.start
Id
Period.start
Type
Cardinality
0 - 1
Definition
The start of the period. The boundary is inclusive.
Comment
If the low element is missing, the meaning is that the low boundary is not known.
Condition
per-1
Path
Observation.device.Reference.identifier.Identifier.period.Period.end
Id
Period.end
Type
Cardinality
0 - 1
Definition
The end of the period. If the end of the period is missing, it means that the period is ongoing. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.
Comment
The high value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has a end value of 2012-02-03.
Condition
per-1
Path
Observation.device.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.device.Reference.identifier.Identifier.assigner.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.device.Reference.identifier.Identifier.assigner.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.device.Reference.identifier.Identifier.assigner.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.device.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.referenceRange
Id
Observation.referenceRange
Type
Cardinality
0 - *
Definition
Guidance on how to interpret the value by comparison to a normal or recommended range.
Comment
Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g., specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.
Requirements
Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.
Constraint
ele-1 [error]
All FHIR elements must have a @value or children
obs-3 [error]
Must have at least a low or a high or text
Path
Observation.referenceRange.low
Id
Observation.referenceRange.low
Type
Cardinality
0 - 1
Definition
The value of the low bound of the reference range. The low bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the low bound is omitted, it is assumed to be meaningless (e.g. reference range is <=2.3).
Comment
Condition
obs-3
Path
Observation.referenceRange.low.Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.referenceRange.low.Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.referenceRange.low.Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.referenceRange.low.Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.referenceRange.low.Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.referenceRange.high
Id
Observation.referenceRange.high
Type
Cardinality
0 - 1
Definition
The value of the high bound of the reference range. The high bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the high bound is omitted, it is assumed to be meaningless (e.g. reference range is >= 2.3).
Comment
Condition
obs-3
Path
Observation.referenceRange.high.Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.referenceRange.high.Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.referenceRange.high.Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.referenceRange.high.Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.referenceRange.high.Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.referenceRange.type
Id
Observation.referenceRange.type
Type
Cardinality
0 - 1
Definition
Codes to indicate the what part of the targeted reference population it applies to. For example, the normal or therapeutic range.
Comment
This SHOULD be populated if there is more than one range. If this element is not present then the normal range is assumed.
Requirements
Need to be able to say what kind of reference range this is - normal, recommended, therapeutic, etc, - for proper interpretation.
Path
Observation.referenceRange.type.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.referenceRange.type.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.referenceRange.type.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.referenceRange.type.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.referenceRange.type.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.referenceRange.type.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.referenceRange.appliesTo
Id
Observation.referenceRange.appliesTo
Type
Cardinality
0 - *
Definition
Codes to indicate the target population this reference range applies to. For example, a reference range may be based on the normal population or a particular sex or race.
Comment
This SHOULD be populated if there is more than one range. If this element is not present then the normal population is assumed.
Requirements
Need to be able to identify the target population for proper interpretation.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.referenceRange.appliesTo.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.referenceRange.age
Id
Observation.referenceRange.age
Type
Cardinality
0 - 1
Definition
The age at which this reference range is applicable. This is a neonatal age (e.g. number of weeks at term) if the meaning says so.
Comment
Requirements
Some analytes vary greatly over age.
Path
Observation.referenceRange.age.Range.low
Id
Range.low
Type
Cardinality
0 - 1
Definition
The low limit. The boundary is inclusive.
Comment
If the low element is missing, the low boundary is not known.
Condition
rng-2
Path
Observation.referenceRange.age.Range.low.Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.referenceRange.age.Range.low.Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.referenceRange.age.Range.low.Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.referenceRange.age.Range.low.Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.referenceRange.age.Range.low.Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.referenceRange.age.Range.high
Id
Range.high
Type
Cardinality
0 - 1
Definition
The high limit. The boundary is inclusive.
Comment
If the high element is missing, the high boundary is not known.
Condition
rng-2
Path
Observation.referenceRange.age.Range.high.Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.referenceRange.age.Range.high.Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.referenceRange.age.Range.high.Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.referenceRange.age.Range.high.Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.referenceRange.age.Range.high.Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.related
Id
Observation.related
Type
Cardinality
0 - *
Definition
A reference to another resource (usually another Observation) whose relationship is defined by the relationship type code.
Comment
For a discussion on the ways Observations can assembled in groups together see [Notes below](observation.html#4.20.4).
Requirements
Normally, an observation will have either a value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and a set of related observations or sometimes a QuestionnaireResponse from which the measure is derived.
Constraint
ele-1 [error]
All FHIR elements must have a @value or children
Path
Observation.related.type
Id
Observation.related.type
Type
Cardinality
0 - 1
Definition
A code specifying the kind of relationship that exists with the target resource.
Comment
The "derived-from" type is the only logical choice when referencing the QuestionnaireAnswer resource.
Requirements
A relationship type SHOULD be provided.
Path
Observation.related.target
Id
Observation.related.target
Type
Cardinality
1 - 1
Definition
A reference to the observation or [QuestionnaireResponse](questionnaireresponse.html#) resource that is related to this observation.
Comment
Path
Observation.related.target.Reference.reference
Id
Reference.reference
Type
Cardinality
0 - 1
Definition
A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.
Comment
Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.
Condition
ref-1
Path
Observation.related.target.Reference.identifier
Id
Reference.identifier
Type
Cardinality
0 - 1
Definition
An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.
Comment
When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference
Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.
Path
Observation.related.target.Reference.identifier.Identifier.use
Id
Identifier.use
Type
Cardinality
0 - 1
Definition
The purpose of this identifier.
Comment
This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Requirements
Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Path
Observation.related.target.Reference.identifier.Identifier.type
Id
Identifier.type
Type
Cardinality
0 - 1
Definition
A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Comment
This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage.
Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.
Requirements
Allows users to make use of identifiers when the identifier system is not known.
Path
Observation.related.target.Reference.identifier.Identifier.system
Id
Identifier.system
Type
Cardinality
0 - 1
Definition
Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Comment
Requirements
There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.
Path
Observation.related.target.Reference.identifier.Identifier.value
Id
Identifier.value
Type
Cardinality
0 - 1
Definition
The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Comment
If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the [Rendered Value extension](extension-rendered-value.html).
Path
Observation.related.target.Reference.identifier.Identifier.period
Id
Identifier.period
Type
Cardinality
0 - 1
Definition
Time period during which identifier is/was valid for use.
Comment
Path
Observation.related.target.Reference.identifier.Identifier.assigner
Id
Identifier.assigner
Type
Cardinality
0 - 1
Definition
Organization that issued/manages the identifier.
Comment
The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.
Path
Observation.related.target.Reference.display
Id
Reference.display
Type
Cardinality
0 - 1
Definition
Plain text narrative that identifies the resource in addition to the resource reference.
Comment
This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.
Path
Observation.component
Id
Observation.component
Type
Cardinality
0 - *
Definition
Some observations have multiple component observations. These component observations are expressed as separate code value pairs that share the same attributes. Examples include systolic and diastolic component observations for blood pressure measurement and multiple component observations for genetics observations.
Comment
For a discussion on the ways Observations can be assembled in groups together see [Notes](observation.html#notes) below.
Requirements
Component observations share the same attributes in the Observation resource as the primary observation and are always treated a part of a single observation (they are not separable). However, the reference range for the primary observation value is not inherited by the component values and is required when appropriate for each component observation.
Constraint
ele-1 [error]
All FHIR elements must have a @value or children
Path
Observation.component.code
Id
Observation.component.code
Type
Cardinality
1 - 1
Definition
Describes what was observed. Sometimes this is called the observation "code".
Comment
Requirements
Knowing what kind of observation is being made is essential to understanding the observation.
Path
Observation.component.code.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.component.code.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.component.code.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.component.code.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.component.code.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.component.code.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.component.value[x]
Id
Observation.component.value[x]
Type
Cardinality
0 - 1
Definition
The information determined as a result of making the observation, if the information has a simple value.
Comment
Normally, an observation will have either a single value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For boolean values use valueCodeableConcept and select codes from (these "yes/no" concepts can be mapped to the display name "true/false" or other mutually exclusive terms that may be needed"). The element, Observation.value[x], has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueRatio, valueChoice, valuePeriod, valueSampleData, or valueString (the name format is "'value' + the type name" with a capital on the first letter of the type).
Requirements
An observation exists to have a value, though it may not if it is in error, or if it represents a group of observations.
Path
Observation.component.value[x].Quantity.value
Id
Quantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Observation.component.value[x].Quantity.comparator
Id
Quantity.comparator
Type
Cardinality
0 - 1
Definition
How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Observation.component.value[x].Quantity.unit
Id
Quantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Observation.component.value[x].Quantity.system
Id
Quantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Observation.component.value[x].Quantity.code
Id
Quantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.
Path
Observation.component.dataAbsentReason
Id
Observation.component.dataAbsentReason
Type
Cardinality
0 - 1
Definition
Provides a reason why the expected value in the element Observation.value[x] is missing.
Comment
"Null" or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "test not done". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Because of these options, use-case agreements are required to interpret general observations for exceptional values.
Requirements
For many results it is necessary to handle exceptional values in measurements.
Binding
Strength
extensible
Description
Codes specifying why the result (Observation.value[x]) is missing.
ValueSet
Condition
obs-6
Path
Observation.component.dataAbsentReason.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.component.dataAbsentReason.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.component.dataAbsentReason.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.component.dataAbsentReason.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.component.dataAbsentReason.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.component.dataAbsentReason.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
Path
Observation.component.interpretation
Id
Observation.component.interpretation
Type
Cardinality
0 - 1
Definition
The assessment made based on the result of the observation. Intended as a simple compact code often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result. Otherwise known as abnormal flag.
Comment
The component interpretation applies only to the individual component value. For an overall interpretation all components together use thes Observation.interpretation element.
Requirements
For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.
Path
Observation.component.interpretation.CodeableConcept.coding
Id
CodeableConcept.coding
Type
Cardinality
0 - *
Definition
A reference to a code defined by a terminology system.
Comment
Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.
Requirements
Allows for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.
Path
Observation.component.interpretation.CodeableConcept.coding.Coding.system
Id
Coding.system
Type
Cardinality
0 - 1
Definition
The identification of the code system that defines the meaning of the symbol in the code.
Comment
The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should de-reference to some definition that establish the system clearly and unambiguously.
Requirements
Need to be unambiguous about the source of the definition of the symbol.
Path
Observation.component.interpretation.CodeableConcept.coding.Coding.version
Id
Coding.version
Type
Cardinality
0 - 1
Definition
The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured. and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.
Comment
Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.
Path
Observation.component.interpretation.CodeableConcept.coding.Coding.code
Id
Coding.code
Type
Cardinality
0 - 1
Definition
A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).
Comment
Requirements
Need to refer to a particular code in the system.
Path
Observation.component.interpretation.CodeableConcept.coding.Coding.display
Id
Coding.display
Type
Cardinality
0 - 1
Definition
A representation of the meaning of the code in the system, following the rules of the system.
Comment
Requirements
Need to be able to carry a human-readable meaning of the code for readers that do not know the system.
Path
Observation.component.interpretation.CodeableConcept.coding.Coding.userSelected
Id
Coding.userSelected
Type
Cardinality
0 - 1
Definition
Indicates that this coding was chosen by a user directly - i.e. off a pick list of available items (codes or displays).
Comment
Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.
Requirements
This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.
referenceRange
Provides guide for interpretation of component result
Path
Observation.component.referenceRange
Id
Observation.component.referenceRange
Type
Cardinality
0 - *
Definition
Guidance on how to interpret the value by comparison to a normal or recommended range.
Comment
Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g., specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.
Requirements
Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.