The findings and interpretation of diagnostic tests performed on patients, groups of patients, devices, and locations, and/or specimens derived from these. The report includes clinical context such as requesting and provider information, and some mix of atomic results, images, textual and coded interpretations, and formatted representation of diagnostic reports.

This is intended to capture a single report and is not suitable for use in displaying summary information that covers multiple reports. For example, this resource has not been designed for laboratory cumulative reporting formats nor detailed structured reports for sequencing.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

An Extension

R5: DiagnosticReport.note (new:Annotation)

Element DiagnosticReport.note has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.note has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). May include general statements about the diagnostic report, or statements about significant, unexpected or unreliable results values contained within the diagnostic report, or information about its source when relevant to its interpretation.

R5: DiagnosticReport.study (new:Reference(GenomicStudy,ImagingStudy))

Element DiagnosticReport.study has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.study has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). For laboratory-type studies like GenomeStudy, type resources will be used for tracking additional metadata and workflow aspects of complex studies. ImagingStudy and the media element are somewhat overlapping - typically, the list of image references in the media element will also be found in one of the imaging study resources. However, each caters to different types of displays for different types of purposes. Neither, either, or both may be provided.

R5: DiagnosticReport.supportingInfo (new:BackboneElement)

Element DiagnosticReport.supportingInfo has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.supportingInfo has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element).

R5: DiagnosticReport.composition (new:Reference(Composition))

Element DiagnosticReport.composition has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.composition has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). The Composition provides structure to the content of the DiagnosticReport (and only contains contents referenced in the DiagnosticReport) - e.g., to order the sections of an anatomic pathology structured report.

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

The status of the diagnostic report.

The status of the diagnostic report.

Diagnostic services routinely issue provisional/incomplete reports, and sometimes withdraw previously released reports.

An Extension

R5: DiagnosticReport.status additional codes

Element DiagnosticReport.status is mapped to FHIR R4 element DiagnosticReport.status as RelatedTo. The mappings for DiagnosticReport.status do not allow expression of the necessary codes, per the bindings on the source and target. The target context DiagnosticReport.status is a modifier element, so this extension does not need to be defined as a modifier.

A code or name that describes this diagnostic report.

Codes that describe Diagnostic Reports.

R5: DiagnosticReport.note (new:Annotation)

Element DiagnosticReport.note has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.note has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). May include general statements about the diagnostic report, or statements about significant, unexpected or unreliable results values contained within the diagnostic report, or information about its source when relevant to its interpretation.

R5: DiagnosticReport.study (new:Reference(GenomicStudy,ImagingStudy))

Element DiagnosticReport.study has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.study has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). For laboratory-type studies like GenomeStudy, type resources will be used for tracking additional metadata and workflow aspects of complex studies. ImagingStudy and the media element are somewhat overlapping - typically, the list of image references in the media element will also be found in one of the imaging study resources. However, each caters to different types of displays for different types of purposes. Neither, either, or both may be provided.

R5: DiagnosticReport.supportingInfo (new:BackboneElement)

Element DiagnosticReport.supportingInfo has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.supportingInfo has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element).

R5: DiagnosticReport.composition (new:Reference(Composition))

Element DiagnosticReport.composition has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.composition has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). The Composition provides structure to the content of the DiagnosticReport (and only contains contents referenced in the DiagnosticReport) - e.g., to order the sections of an anatomic pathology structured report.

R5: DiagnosticReport.status additional codes

Element DiagnosticReport.status is mapped to FHIR R4 element DiagnosticReport.status as RelatedTo. The mappings for DiagnosticReport.status do not allow expression of the necessary codes, per the bindings on the source and target. The target context DiagnosticReport.status is a modifier element, so this extension does not need to be defined as a modifier.

R5: DiagnosticReport.subject

Element DiagnosticReport.subject is mapped to FHIR R4 element DiagnosticReport.subject as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R5 element DiagnosticReport.subject with unmapped reference targets: BiologicallyDerivedProduct, Medication, Organization, Practitioner, Substance.

R5: DiagnosticReport.media.link additional types from child elements (display, identifier, reference, type)

Element DiagnosticReport.media.link is mapped to FHIR R4 element DiagnosticReport.media.link as SourceIsBroaderThanTarget. The mappings for DiagnosticReport.media.link do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R5 element DiagnosticReport.media.link with unmapped reference targets: DocumentReference.

The findings and interpretation of diagnostic tests performed on patients, groups of patients, devices, and locations, and/or specimens derived from these. The report includes clinical context such as requesting and provider information, and some mix of atomic results, images, textual and coded interpretations, and formatted representation of diagnostic reports.

This is intended to capture a single report and is not suitable for use in displaying summary information that covers multiple reports. For example, this resource has not been designed for laboratory cumulative reporting formats nor detailed structured reports for sequencing.

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

The base language in which the resource is written.

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

The codes SHOULD be taken from CommonLanguages
(preferred to http://hl7.org/fhir/ValueSet/languages|4.0.1)

A human language.

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels.

An Extension

R5: DiagnosticReport.note (new:Annotation)

Element DiagnosticReport.note has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.note has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). May include general statements about the diagnostic report, or statements about significant, unexpected or unreliable results values contained within the diagnostic report, or information about its source when relevant to its interpretation.

R5: DiagnosticReport.study (new:Reference(GenomicStudy,ImagingStudy))

Element DiagnosticReport.study has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.study has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). For laboratory-type studies like GenomeStudy, type resources will be used for tracking additional metadata and workflow aspects of complex studies. ImagingStudy and the media element are somewhat overlapping - typically, the list of image references in the media element will also be found in one of the imaging study resources. However, each caters to different types of displays for different types of purposes. Neither, either, or both may be provided.

R5: DiagnosticReport.supportingInfo (new:BackboneElement)

Element DiagnosticReport.supportingInfo has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.supportingInfo has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element).

R5: DiagnosticReport.composition (new:Reference(Composition))

Element DiagnosticReport.composition has a context of DiagnosticReport based on following the parent source element upwards and mapping to DiagnosticReport. Element DiagnosticReport.composition has no mapping targets in FHIR R4. Typically, this is because the element has been added (is a new element). The Composition provides structure to the content of the DiagnosticReport (and only contains contents referenced in the DiagnosticReport) - e.g., to order the sections of an anatomic pathology structured report.

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

Identifiers assigned to this report by the performer or other systems.

Usually assigned by the Information System of the diagnostic service provider (filler id).

Need to know what identifier to use when making queries about this report from the source laboratory, and for linking to the report outside FHIR context.

Details concerning a service requested.

Note: Usually there is one test request for each result, however in some circumstances multiple test requests may be represented using a single test result resource. Note that there are also cases where one request leads to multiple reports.

This allows tracing of authorization for the report and tracking whether proposals/recommendations were acted upon.

The status of the diagnostic report.

The status of the diagnostic report.

Diagnostic services routinely issue provisional/incomplete reports, and sometimes withdraw previously released reports.

unique id for the element within a resource (for internal references)

An Extension

R5: DiagnosticReport.status additional codes

Element DiagnosticReport.status is mapped to FHIR R4 element DiagnosticReport.status as RelatedTo. The mappings for DiagnosticReport.status do not allow expression of the necessary codes, per the bindings on the source and target. The target context DiagnosticReport.status is a modifier element, so this extension does not need to be defined as a modifier.

Primitive value for code

A code that classifies the clinical discipline, department or diagnostic service that created the report (e.g. cardiology, biochemistry, hematology, MRI). This is used for searching, sorting and display purposes.

Multiple categories are allowed using various categorization schemes. The level of granularity is defined by the category concepts in the value set. More fine-grained filtering can be performed using the metadata and/or terminology hierarchy in DiagnosticReport.code.

Codes for diagnostic service sections.

A code or name that describes this diagnostic report.

Codes that describe Diagnostic Reports.

The subject of the report. Usually, but not always, this is a patient. However, diagnostic services also perform analyses on specimens collected from a variety of other sources.

SHALL know the subject context.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

R5: DiagnosticReport.subject

Element DiagnosticReport.subject is mapped to FHIR R4 element DiagnosticReport.subject as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R5 element DiagnosticReport.subject with unmapped reference targets: BiologicallyDerivedProduct, Medication, Organization, Practitioner, Substance.

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.

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.

The expected type of the target of the reference. If both Reference.type and Reference.reference are populated and Reference.reference is a FHIR URL, both SHALL be consistent.

The type is the Canonical URL of Resource Definition that is the type this reference refers to. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition/ e.g. "Patient" is a reference to http://hl7.org/fhir/StructureDefinition/Patient. Absolute URLs are only allowed for logical models (and can only be used in references in logical models, not resources).

This element is used to indicate the type of the target of the reference. This may be used which ever of the other elements are populated (or not). In some cases, the type of the target may be determined by inspection of the reference (e.g. a RESTful URL) or by resolving the target of the reference; if both the type and a reference is provided, the reference SHALL resolve to a resource of the same type as that specified.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|4.0.1)

Aa resource (or, for logical models, the URI of the logical model).

An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents 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.

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.

Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

Plain text narrative that identifies the resource in addition to the resource reference.

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.

The healthcare event (e.g. a patient and healthcare provider interaction) which this DiagnosticReport is about.

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 but still be tied to the context of the encounter (e.g. pre-admission laboratory tests).

Links the request to the Encounter context.

The time or time-period the observed values are related to. When the subject of the report is a patient, this is usually either the time of the procedure or of specimen collection(s), but very often the source of the date/time is not known, only the date/time itself.

If the diagnostic procedure was performed on the patient, this is the time it was performed. If there are specimens, the diagnostically relevant time can be derived from the specimen collection times, but the specimen information is not always available, and the exact relationship between the specimens and the diagnostically relevant time is not always automatic.

Need to know where in the patient history to file/present this report.

The date and time that this version of the report was made available to providers, typically after the report was reviewed and verified.

May be different from the update time of the resource itself, because that is the status of the record (potentially a secondary copy), not the actual release time of the report.

Clinicians need to be able to check the date that the report was released.

The diagnostic service that is responsible for issuing the report.

This is not necessarily the source of the atomic data items or the entity that interpreted the results. It is the entity that takes responsibility for the clinical report.

Need to know whom to contact if there are queries about the results. Also may need to track the source of reports for secondary data analysis.

The practitioner or organization that is responsible for the report's conclusions and interpretations.

Might not be the same entity that takes responsibility for the clinical report.

Need to know whom to contact if there are queries about the results. Also may need to track the source of reports for secondary data analysis.

Details about the specimens on which this diagnostic report is based.

If the specimen is sufficiently specified with a code in the test result name, then this additional data may be redundant. If there are multiple specimens, these may be represented per observation or group.

Need to be able to report information about the collected specimens on which the report is based.

Observations that are part of this diagnostic report.

Observations can contain observations.

Need to support individual results, or groups of results, where the result grouping is arbitrary, but meaningful.

One or more links to full details of any imaging performed during the diagnostic investigation. Typically, this is imaging performed by DICOM enabled modalities, but this is not required. A fully enabled PACS viewer can use this information to provide views of the source images.

ImagingStudy and the image element are somewhat overlapping - typically, the list of image references in the image element will also be found in one of the imaging study resources. However, each caters to different types of displays for different types of purposes. Neither, either, or both may be provided.

A list of key images associated with this report. The images are generally created during the diagnostic process, and may be directly of the patient, or of treated specimens (i.e. slides of interest).

Many diagnostic services include images in the report as part of their service.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

A comment about the image. Typically, this is used to provide an explanation for why the image is included, or to draw the viewer's attention to important features.

The comment should be displayed with the image. It would be common for the report to include additional discussion of the image contents in other sections such as the conclusion.

The provider of the report should make a comment about each image included in the report.

Reference to the image source.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

R5: DiagnosticReport.media.link additional types from child elements (display, identifier, reference, type)

Element DiagnosticReport.media.link is mapped to FHIR R4 element DiagnosticReport.media.link as SourceIsBroaderThanTarget. The mappings for DiagnosticReport.media.link do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R5 element DiagnosticReport.media.link with unmapped reference targets: DocumentReference.

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.

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.

The expected type of the target of the reference. If both Reference.type and Reference.reference are populated and Reference.reference is a FHIR URL, both SHALL be consistent.

The type is the Canonical URL of Resource Definition that is the type this reference refers to. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition/ e.g. "Patient" is a reference to http://hl7.org/fhir/StructureDefinition/Patient. Absolute URLs are only allowed for logical models (and can only be used in references in logical models, not resources).

This element is used to indicate the type of the target of the reference. This may be used which ever of the other elements are populated (or not). In some cases, the type of the target may be determined by inspection of the reference (e.g. a RESTful URL) or by resolving the target of the reference; if both the type and a reference is provided, the reference SHALL resolve to a resource of the same type as that specified.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|4.0.1)

Aa resource (or, for logical models, the URI of the logical model).

An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents 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.

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.

Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

Plain text narrative that identifies the resource in addition to the resource reference.

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.

Concise and clinically contextualized summary conclusion (interpretation/impression) of the diagnostic report.

Need to be able to provide a conclusion that is not lost among the basic result data.

One or more codes that represent the summary conclusion (interpretation/impression) of the diagnostic report.

Diagnosis codes provided as adjuncts to the report.

Rich text representation of the entire result as issued by the diagnostic service. Multiple formats are allowed but they SHALL be semantically equivalent.

"application/pdf" is recommended as the most reliable and interoperable in this context.

Gives laboratory the ability to provide its own fully formatted report for clinical fidelity.