FHIR Observation
The Observation resource captures measurements and simple assertions: lab results, vital signs, social-history answers, and more. Its `code` says what was observed and its `value[x]` carries the result, scoped to a `subject` and an `effective[x]` time.
US Core requirements
The elements below come from the profiles in our catalog that target Observation. “Required” elements fail validation if absent; recommended elements are Must Support but do not fail on their own.
US Core Laboratory Result Observation (6.1)
http://hl7.org/fhir/us/core/StructureDefinition/us-core-observation-lab
Required
Observation.status— US Core requires Observation.status.Observation.category— US Core requires Observation.category (laboratory).Observation.code— US Core requires Observation.code (LOINC).Observation.subject— US Core requires Observation.subject.
Recommended
Observation.effectiveDateTime— US Core requires Observation.effective[x] — dateTime, Period, Timing, or instant.Observation.effectivePeriod— US Core requires Observation.effective[x] — dateTime, Period, Timing, or instant.Observation.valueQuantity— US Core requires Observation.value[x] OR Observation.dataAbsentReason.Observation.valueCodeableConcept— US Core requires Observation.value[x] OR Observation.dataAbsentReason.Observation.valueString— US Core requires Observation.value[x] OR Observation.dataAbsentReason.Observation.dataAbsentReason— US Core requires Observation.value[x] OR Observation.dataAbsentReason.
IPS Observation Results
http://hl7.org/fhir/uv/ips/StructureDefinition/Observation-results-uv-ips
Required
Observation.status— IPS requires Observation.status.Observation.code— IPS requires Observation.code.Observation.subject— IPS requires Observation.subject (Patient reference).Observation.performer— IPS requires Observation.performer.
Recommended
Observation.effectiveDateTime— IPS requires Observation.effective[x].Observation.effectivePeriod— IPS requires Observation.effective[x].
AU Core Diagnostic Result Observation (2.0.0)
http://hl7.org.au/fhir/core/StructureDefinition/au-core-diagnosticresult
Required
Observation.status— AU Core requires Observation.status (registered | preliminary | final | amended | ...).Observation.category— AU Core requires Observation.category on a diagnostic result.Observation.code— AU Core requires Observation.code describing what was observed.Observation.subject— AU Core requires Observation.subject (AU Core Patient reference).
Recommended
Observation.effectiveDateTime— AU Core requires Observation.effective[x] — dateTime, Period, Timing, or instant.Observation.effectivePeriod— AU Core requires Observation.effective[x] — dateTime, Period, Timing, or instant.Observation.valueQuantity— AU Core flags Observation.value[x] OR dataAbsentReason as Must Support.Observation.valueCodeableConcept— AU Core flags Observation.value[x] OR dataAbsentReason as Must Support.Observation.valueString— AU Core flags Observation.value[x] OR dataAbsentReason as Must Support.Observation.dataAbsentReason— AU Core flags Observation.value[x] OR dataAbsentReason as Must Support.
Minimal valid example
A minimal FHIR R4 Observation that satisfies the common required elements:
{
"resourceType": "Observation",
"status": "final",
"category": [
{
"coding": [
{
"system": "http://terminology.hl7.org/CodeSystem/observation-category",
"code": "laboratory"
}
]
}
],
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "2345-7",
"display": "Glucose"
}
]
},
"subject": {
"reference": "Patient/example"
},
"effectiveDateTime": "2024-01-15T13:55:00Z",
"valueQuantity": {
"value": 110,
"unit": "mg/dL",
"system": "http://unitsofmeasure.org",
"code": "mg/dL"
}
}Common validation failures
- Missing `status`, which is required. Common valid values are `final`, `preliminary`, `corrected`, `cancelled`.
- Neither `value[x]` nor `dataAbsentReason` present. One is required; you cannot omit both.
- `code` without a recognized system (e.g. LOINC `http://loinc.org`). A bare local code fails terminology binding expectations.
- Missing `subject` reference, or missing `effective[x]` (effectiveDateTime / effectivePeriod).
Frequently asked questions
What is the FHIR Observation resource?
The Observation resource captures measurements and simple assertions: lab results, vital signs, social-history answers, and more. Its `code` says what was observed and its `value[x]` carries the result, scoped to a `subject` and an `effective[x]` time.
What are the US Core, IPS & AU Core required elements for Observation?
For US Core Laboratory Result Observation (6.1), the elements marked required (error severity) are: Observation.status, Observation.category, Observation.code, Observation.subject. For IPS Observation Results, the elements marked required (error severity) are: Observation.status, Observation.code, Observation.subject, Observation.performer. For AU Core Diagnostic Result Observation (2.0.0), the elements marked required (error severity) are: Observation.status, Observation.category, Observation.code, Observation.subject. Recommended (Must Support but not failing) elements are also flagged by the coverage tool.
How do I validate a FHIR Observation?
Paste the resource into the FHIR validator for a structural parse and conformance score, or use the coverage tool to score it against a specific profile like US Core. Both run in your browser, so PHI never leaves your device.
What are common Observation validation failures?
Missing `status`, which is required. Common valid values are `final`, `preliminary`, `corrected`, `cancelled`. Neither `value[x]` nor `dataAbsentReason` present. One is required; you cannot omit both.