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What is an Observation?
The Observation resource represents a measurement or assertion about a patient — vital signs, laboratory results, imaging findings, clinical scores, or social history. It is one of the most commonly used FHIR resources.
Key elements
status— registered, preliminary, final, amended, corrected, cancelledcategory— vital-signs, laboratory, imaging, social-history, survey, examcode— what was observed, coded with LOINC (preferred), SNOMED CT, or local codessubject— reference to the Patient (or Group, Device, Location)effective[x]— when the observation was made (dateTime, Period, Timing, instant)value[x]— the result: Quantity, CodeableConcept, string, boolean, Range, Ratiocomponent— for multi-part observations (blood pressure: systolic + diastolic)referenceRange— normal range for interpretation
LOINC codes used in practice
| LOINC | Description | Unit |
|---|---|---|
| 29463-7 | Body weight | kg |
| 8310-5 | Body temperature | Cel |
| 55284-4 | Blood pressure (panel) | — |
| 8480-6 | Systolic blood pressure | mm[Hg] |
| 8462-4 | Diastolic blood pressure | mm[Hg] |
| 2339-0 | Blood glucose | mmol/L |