CodeSystem/$lookup

Resolves a code in a CodeSystem and returns concept details such as display, designations, properties, abstract status, and version.

FHIR Specification

See the official FHIR specification for supported request parameters and response parameters: https://www.hl7.org/fhir/codesystem-operation-lookup.html.

Response

Returns a FHIR Parameters resource. Common output parameters include code, display, name, system, abstract, version, designation, and property.

Custom CodeSystem property example

This example resolves a code from the CodeSystem created in the CodeSystem resource guide and asks for the custom prop property.

GET /CodeSystem/$lookup?system=http://example.org/CodeSystem/cs1&code=code1&property=prop

POST /CodeSystem/$lookup
Content-Type: application/fhir+json

{
  "resourceType": "Parameters",
  "parameter": [
    { "name": "system", "valueUri": "http://example.org/CodeSystem/cs1" },
    { "name": "code", "valueCode": "code1" },
    { "name": "property", "valueCode": "prop" }
  ]
}

{
  "resourceType": "Parameters",
  "parameter": [
    { "name": "code", "valueCode": "code1" },
    { "name": "display", "valueString": "Display 1" },
    { "name": "name", "valueString": "ExampleCodeSystem" },
    { "name": "system", "valueUri": "http://example.org/CodeSystem/cs1" },
    { "name": "abstract", "valueBoolean": false },
    { "name": "version", "valueString": "0.1.0" },
    {
      "name": "designation",
      "part": [
        { "name": "language", "valueCode": "en" },
        {
          "name": "use",
          "valueCoding": {
            "system": "http://terminology.hl7.org/CodeSystem/hl7TermMaintInfra",
            "code": "preferredForLanguage"
          }
        },
        { "name": "value", "valueString": "Display 1" }
      ]
    },
    {
      "name": "designation",
      "part": [
        { "name": "language", "valueCode": "de-DE" },
        { "name": "value", "valueString": "Anzeige 1" }
      ]
    },
    {
      "name": "property",
      "part": [
        { "name": "code", "valueCode": "prop" },
        { "name": "value", "valueCode": "old" }
      ]
    },
    {
      "name": "property",
      "part": [
        { "name": "code", "valueCode": "inactive" },
        { "name": "value", "valueBoolean": false }
      ]
    }
  ]
}

This example uses the CodeSystem created in the CodeSystem resource guide.

SNOMED CT lookup example

This example resolves the SNOMED CT code 73211009 and returns its display and system metadata.

GET /CodeSystem/$lookup?system=http://snomed.info/sct&code=73211009
Accept: application/fhir+json

POST /CodeSystem/$lookup
Content-Type: application/fhir+json
Accept: application/fhir+json

{
  "resourceType": "Parameters",
  "parameter": [
    { "name": "system", "valueUri": "http://snomed.info/sct" },
    { "name": "code", "valueCode": "73211009" }
  ]
}

{
  "resourceType": "Parameters",
  "parameter": [
    { "name": "code", "valueCode": "73211009" },
    { "name": "display", "valueString": "Diabetes mellitus" },
    { "name": "name", "valueString": "snomed-ct" },
    { "name": "system", "valueUri": "http://snomed.info/sct" },
    { "name": "abstract", "valueBoolean": false },
    { "name": "version", "valueString": "http://snomed.info/sct/900000000000207008/version/20260701" },
    {
      "name": "property",
      "part": [
        { "name": "code", "valueCode": "inactive" },
        { "name": "value", "valueBoolean": false }
      ]
    }
  ]
}