Please note:

This version of the UK Core is a development copy.
This contains BREAKING CHANGES as a result of the C&TA Sprint 7 Review, and STU2 Sequence ballot reconciliation.
This version is not yet reviewed for implementation. Other versions are available on the UK Core Version History Guide
Please follow the guidance on the Contact Us page if you need any assistance.
A summary of changes is available on the STU3 Sequence Change Log

Extensions Index

This extension library contains all the extensions Clinically and Technically Assured for use with UK Core. The profiles are found in the ProfilesIndex. The table below lists all the current extensions and the context of use.

The context of use column indicates the profile and /or element where the extension may be applied. The modifier extension column indicates whether the extension is a modifier extension or not.

The general rule is extensions can be ignored by receivers*. When a modifier extension is received it SHALL NOT be ignored as it modifies the meaning of the element or elements that contains it. Typically, this means information that qualifies or negates the primary meaning of the element that contains it.

For more information from HL7 about FHIR extensions

For more information from HL7 about FHIR Modifier extensions

*There may be specific use cases where this is not the case and the Domain Implementation Guidance associated with the use case SHOULD be consulted.

Important

The Extensions are rendered in several formats:

Tree: a fully calculated form of the Extension that is not dependent on any other structure
Detailed: a fully calculated form of the Extension in table form
Table: a tabular view of the differential Extension elements
XML: a rendering of a XML view of the Extension
JSON: a rendering of a JSON view of the Extension

Further information from HL7 relating to extensibility is available.

UK Core Extensions

The Extensions listed below have been defined as UK Core extensions. Also included in this library are some HL7 core-defined extensions which have been added to the UK Core profiles because they have been deemed to be "core" to UK FHIR data exchanges. These will have a page with guidance on usage in the UK and examples to illustrate usage.

Note: implementers of UK Core MAY use any HL7 core-defined extension from the HL7 standard regardless of whether the extension is included in this implementation guide. The list of core-defined extensions in FHIR R4 is available in the HL7 Core-defined Extension Registry.

Implementers of the UK Core profiles MAY also create their own Extensions where required, but are encouraged to engage with the UK Core development process to ensure that there is not an existing suitable extension available, and to assist in guidance around the use of an extension with the UK Core, and with wider use by the UK FHIR Community.

Id	Context of Use	Status
Extension-UKCore-AdditionalContact	ServiceRequest	active
Extension-UKCore-AddressKey	Address	active
Extension-UKCore-AdmissionMethod	Encounter.hospitalization	active
Extension-UKCore-AllergyIntoleranceEnd	AllergyIntolerance.clinicalStatus	active
Extension-UKCore-AssociatedEncounter	FamilyMemberHistory	active
Extension-UKCore-BirthSex	Patient	active
Extension-UKCore-BookingOrganization	Appointment	active
Extension-UKCore-CareSettingType	Composition, List	active
Extension-UKCore-CodingSCTDescDisplay	Coding	active
Extension-UKCore-ConditionEpisode	Condition	active
Extension-UKCore-ContactPreference	Patient, RelatedPerson	active
Extension-UKCore-ContactRank	Patient.contact	active
Extension-UKCore-CopyCorrespondenceIndicator	Patient.contact, RelatedPerson	active
Extension-UKCore-Coverage	ServiceRequest	active
Extension-UKCore-CuffSize	Device	active
Extension-UKCore-DeathNotificationStatus	Patient	active
Extension-UKCore-DeliveryChannel	Appointment, Slot	active
Extension-UKCore-DeviceReference	DiagnosticReport.performer, DiagnosticReport.resultsInterpreter	active
Extension-UKCore-DischargeMethod	Encounter	active
Extension-UKCore-EmergencyCareDischargeStatus	Encounter	active
Extension-UKCore-EthnicCategory	Patient	active
Extension-UKCore-Evidence	AllergyIntolerance	active
Extension-UKCore-LegalStatus	Encounter	active
Extension-UKCore-ListWarningCode	List	active
Extension-UKCore-MainLocation	Organization	active
Extension-UKCore-MedicationPrescribingOrganizationType	MedicationStatement	active
Extension-UKCore-MedicationRepeatInformation	MedicationRequest	active
Extension-UKCore-MedicationStatementLastIssueDate	MedicationStatement	active
Extension-UKCore-MedicationTradeFamily	Medication	active
Extension-UKCore-NHSNumberUnavailableReason	Patient	active
Extension-UKCore-NHSNumberVerificationStatus	Patient.identifier	active
Extension-UKCore-OtherContactSystem	ContactPoint.system	active
Extension-UKCore-OutcomeOfAttendance	Encounter	active
Extension-UKCore-ParentPresent	Immunization	active
Extension-UKCore-PharmacistVerifiedIndicator	MedicationStatement	active
Extension-UKCore-PriorityReason	ServiceRequest.priority	active
Extension-UKCore-RecordingSetting	Observation	active
Extension-UKCore-ResidentialStatus	Patient	active
Extension-UKCore-SampleCategory	Specimen	active
Extension-UKCore-SourceOfServiceRequest	ServiceRequest	active
Extension-UKCore-VaccinationProcedure	Immunization	active

Cross Version Extensions

Elements from other FHIR versions can be used within R4 by applying the relevant cross‑version extension packages. This enables implementers to incorporate newer elements without fully upgrading to a newer FHIR release.

Links for the R5 elements to R4 can be found at https://hl7.org/fhir/uv/xver-r5.r4/0.1.0/

See HL7 Confluence: Cross Version Extensions FAQs for more details

R6 Cross-version extensions

A cross version extension package is expected to be released when R6 has become normative. Until then extensions will have to be created manually. Below is a list that have been created. Note: these extensions will be removed once the new xver-r6.r4 extension package has been released.

Id	Context of Use	url	Status
Extension-UKCore-ConditionBodyStructure	Condition	http://hl7.org/fhir/6.0/StructureDefinition/extension-Condition.bodyStructure	draft
Extension-UKCore-ObservationOrganizer	Observation	http://hl7.org/fhir/6.0/StructureDefinition/extension-Observation.organizer	draft
Extension-UKCore-PatientFetalStatus	Patient	http://hl7.org/fhir/6.0/StructureDefinition/extension-Patient.fetalStatus	draft

HL7 Core-defined Extensions

The following HL7 Core-defined Extensions have been agreed as suitable to be included for use with the UK Core Profiles because the use case for an Extension is fully met by a pre-existing HL7 Core-defined Extension.

Implementers of the UK Core profiles MAY also use other HL7 core-defined extensions to extend the UK Core if required by the local implementation, but are encouraged to engage with the UK Core development process to add guidance into the UK Core for wider use by the UK FHIR Community.

HL7 Core-defined Extension	Context of Use	Related Profile	Modifier Extension
Extension coding-sctdescid	Coding	Use on Element ID Coding	NO
Extension observation-bodyPosition	Observation	UKCore-Observation-VitalSigns	NO
Extension organization-period	Organization	UKCore-Organization	NO
Extension patient-birthPlace	Patient	UKCore-Patient	NO
Extension patient-birthTime	Patient.birthDate	UKCore-Patient	NO
Extension patient-cadavericDonor	Patient	UKCore-Patient	NO
Extension patient-interpreterRequired	Patient	UKCore-Patient	NO
Core-defined Extension patient-proficiency	Patient	UKCore-Patient	NO
Extension specimen-specialHandling	Specimen.collection	UKCore-Specimen	NO