Measurements and simple assertions made about a patient, device or other subject.

0. References

1. Read

Return a single Observation for the specified id.

All requests SHALL contain a valid ‘Authorization’ header and SHALL contain an ‘Accept’ header. The `Accept` header indicates the format of the response the client is able to understand, this will be one of the following application/json+fhir or application/xml+fhir.

1.1. Response

A full set of response codes can be found here API Response Codes. FHIR Servers SHALL support the following response codes:

200 successful operation
404 resource not found
410 resource deleted

Fetches a bundle of all Observation resources for the specified patient.

All requests SHALL contain a valid ‘Authorization’ header and SHALL contain an ‘Accept’ header. The `Accept` header indicates the format of the response the client is able to understand, this will be one of the following application/json+fhir or application/xml+fhir.

2.1. Search Parameters

This implementation guide outlines some suggested search parameters for the Observation resource in the table below. To be conformant, provider systems are required to implement all of the SHALL parameters. Provider systems may implement the full list of search parameters for the Observation resource (HL7 FHIR DSTU2 Observation).


Name Type Description Conformance Path
category token The classification of the type of observation SHOULD Observation.category
code token The code of the observation type SHOULD Observation.code
date date Obtained date/time.
If the obtained element is a period, a date that falls in the period
SHALL Observation.effective[x]
patient reference The subject that the observation is about (if patient) SHALL Observation.subject (Patient)

Systems SHOULD support the following search combinations:

  • patient + category
  • patient + category + date
  • patient + category + code
  • patient + category + code + date

2.1.1. category

See token for details on this parameter.

To filter on category ( see profile/valueset for codes )

GET [baseUrl]/Observation?patient=1&category=exam

Return all Observation resources with a category of exam and Patient with a logical id of 1.

2.1.2. code

See token for details on this parameter. ‘code’ can be used multiple times as a search parameter

system is a uniform resource identifier which defines which CodeSystem the code belongs to. This is optional and if not present all matching codes will be returned regardles of CodeSystems.

To search for Observations with Baseline body mass index using SNOMED CT

GET [baseUrl]/Observation?patient=[id]&code=http://snomed.info/sct|846931000000101

Return all Observation resources with SNOMED CT code of 846931000000101 and Patient with a logical id of 1.
GET [baseUrl]/Observation?patient=1&code=846931000000101

Return all Observation resources with code of 846931000000101 from any CodeSystem and Patient with a logical id of 1.

2.1.3. date

See date for details on this parameter. ‘date’ can be used multiple times as a search parameter

GET [baseUrl]/Observation?patient=1&date=ge2010-01-01&date=le2011-12-31

Return all Observation resources that have a date greater than or equal to 1st Jan 2010, a date less than or equal to 31st Dec 2011 and Patient with a logical id of 1.

2.1.4. patient

See reference for details on this parameter. The patient parameter can be used two ways:

This SHALL be supported for all endpoint provider systems.

id is the logical id of the patient on the server which can be obtained by a Patient resource query.

GET [baseUrl]/Observation?patient=42

Return all Observation resources for Patients with a logical id of 42

This SHOULD be supported by middleware systems (e.g. enterprise application integration (EAI) and the enterprise service bus (ESB)) and MAY be supported for endpoint provider systems.

system is a uniform resource identifier which defines which CodeSystem the identifer belongs to. For NHS Number this would be https://fhir.nhs.uk/Id/nhs-number and code would be the NHS Number.

GET [baseUrl]/Observation?patient.identifier=https://fhir.nhs.uk/Id/nhs-number|9876543210

Return all Observation resources for Patients with a NHS Number of 9876543210

2.2. Search Response

If the search fails (cannot be executed, not that there is no matches), the return value is a status code 4xx or 5xx with an OperationOutcome.

If the search succeeds, the return content is a Bundle with type = searchset containing the results of the search as a list of resources in a defined order. The result list can be long, so servers MAY use paging. If they do, they SHALL use this Paging method for breaking the list into pages if appropriate. The server MAY also return an OperationOutcome resource with additional information about the search; if one is sent it SHALL NOT include any errors, and it shall be marked with an entry mode of include.

A full set of response codes can be found here API Response Codes. FHIR Servers SHALL support the following response codes:

200 successful operation
404 resource not found
410 resource deleted

3. Example

3.1. Request Query

Return all Observation resources for Patient with NHS Number of 9876543210, the format of the response body will be xml. Replace ‘baseUrl’ with the actual base Url of the FHIR Server.

3.1.1. cURL

curl -H 'Accept: application/xml+fhir' -H 'Authorization: BEARER [token]' -X GET  '[baseUrl]/Observation?patient.identifier=https://fhir.nhs.uk/Id/nhs-number|9876543210'

3.2 Query Response

3.2.1 Http Headers

3.2.2. Http Body