Observation

Maturity Level	Security Category	Resource Category
Normative	Patient	Clinical

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

Resource Content

Name	Required	Type	Description & Constraints
identifier		Identifier	Business Identifier for observation
basedOn		Reference(CarePlan \| DeviceRequest \| ImmunizationRecommendation \| MedicationRequest \| NutritionOrder \| ServiceRequest)	Fulfills plan, proposal or order
partOf		Reference(MedicationAdministration \| MedicationDispense \| MedicationStatement \| Procedure \| Immunization \| ImagingStudy)	Part of referenced event
status	✓	code	registered \| preliminary \| final \| amended +
category		CodeableConcept	Classification of type of observation
code	✓	CodeableConcept	Type of observation (code / type)
subject		Reference(Patient \| Group \| Device \| Location)	Who and/or what the observation is about
focus		Reference(Any)	What the observation is about, when it is not about the subject of record
encounter		Reference(Encounter)	Healthcare event during which this observation is made
effective[x]		*	Clinically relevant time/time-period for observation
└─ effectiveDateTime		dateTime	Date/time of observation
└─ effectivePeriod		Period	Period of observation
└─ effectiveTiming		Timing	Timing of observation
└─ effectiveInstant		instant	Instant of observation
issued		instant	Date/Time this version was made available
performer		Reference(Practitioner \| PractitionerRole \| Organization \| CareTeam \| Patient \| RelatedPerson)	Who is responsible for the observation
value[x]		Quantity \| CodeableConcept \| string \| boolean \| integer \| Range \| Ratio \| SampledData \| time \| dateTime \| Period	Actual result*
dataAbsentReason		CodeableConcept	Why the result is missing
interpretation		CodeableConcept	High, low, normal, etc.
note		Annotation	Comments about the observation
bodySite		CodeableConcept	Observed body part
method		CodeableConcept	How it was done
specimen		Reference(Specimen)	Specimen used for this observation
device		Reference(Device \| DeviceMetric)	(Measurement) Device
referenceRange		*	Provides guide for interpretation
└─ low		Quantity	Low Range
└─ high		Quantity	High Range
└─ type		CodeableConcept	Reference range qualifier
└─ appliesTo		*	Reference range population
└─ age		Range	Applicable age range
└─ text		string	Text based reference range
hasMember		Reference(Observation \| QuestionnaireResponse \| MolecularSequence)	Related resource that belongs to the Observation group
derivedFrom		Reference(DocumentReference \| ImagingStudy \| Media \| QuestionnaireResponse \| Observation \| MolecularSequence)	Related measurements the observation is made from
component		*	Component results
└─ code		CodeableConcept	Type of component observation
└─ value[x]		Quantity \| CodeableConcept \| string \| boolean \| integer \| Range \| Ratio \| SampledData \| time \| dateTime \| Period	Actual component result*
└─ dataAbsentReason		CodeableConcept	Why the component result is missing
└─ interpretation		CodeableConcept	High, low, normal, etc.
└─ referenceRange		*	Provides guide for interpretation of component result
signature		Signature	Digital Signature

Search Parameters

Name	Type	Description	Expression
code	token	The code of the observation type	`Observation.code`
date	date	Obtained date/time. If the obtained element is a period, a date that falls in the period	`Observation.effective`
identifier	token	The unique id for a particular observation	`Observation.identifier`
patient	reference	The subject that the observation is about (if patient)	`Observation.subject.where(resolve() is Patient)`
encounter	reference	Encounter related to the observation	`Observation.encounter`
based-on	reference	Reference to the service request.	`Observation.basedOn`
category	token	The classification of the type of observation	`Observation.category`
combo-code	token	The code of the observation type or component type	`Observation.code \| Observation.component.code`
combo-data-absent-reason	token	The reason why the expected value in the element Observation.value[x] or Observation.component.value[x] is missing.	`Observation.dataAbsentReason \| Observation.component.dataAbsentReason`
combo-value-concept	token	The value or component value of the observation, if the value is a CodeableConcept	`Observation.value as CodeableConcept \| Observation.component.value as CodeableConcept`
combo-value-quantity	quantity	The value or component value of the observation, if the value is a Quantity, or a SampledData (just search on the bounds of the values in sampled data)	`Observation.value as Quantity \| Observation.value as SampledData \| Observation.component.value as Quantity \| Observation.component.value as SampledData`
component-code	token	The component code of the observation type	`Observation.component.code`
component-data-absent-reason	token	The reason why the expected value in the element Observation.component.value[x] is missing.	`Observation.component.dataAbsentReason`
component-value-concept	token	The value of the component observation, if the value is a CodeableConcept	`Observation.component.value as CodeableConcept`
component-value-quantity	quantity	The value of the component observation, if the value is a Quantity, or a SampledData (just search on the bounds of the values in sampled data)	`Observation.component.value as Quantity \| Observation.component.value as SampledData`
data-absent-reason	token	The reason why the expected value in the element Observation.value[x] is missing.	`Observation.dataAbsentReason`
derived-from	reference	Related measurements the observation is made from	`Observation.derivedFrom`
device	reference	The Device that generated the observation data.	`Observation.device`
focus	reference	The focus of an observation when the focus is not the patient of record.	`Observation.focus`
has-member	reference	Related resource that belongs to the Observation group	`Observation.hasMember`
method	token	The method used for the observation	`Observation.method`
part-of	reference	Part of referenced event	`Observation.partOf`
performer	reference	Who performed the observation	`Observation.performer`
specimen	reference	Specimen used for this observation	`Observation.specimen`
status	token	The status of the observation	`Observation.status`
subject	reference	The subject that the observation is about	`Observation.subject`
value-concept	token	The value of the observation, if the value is a CodeableConcept	`Observation.value as CodeableConcept`
value-date	date	The value of the observation, if the value is a date or period of time	`Observation.value as dateTime \| Observation.value as Period`
value-quantity	quantity	The value of the observation, if the value is a Quantity, or a SampledData (just search on the bounds of the values in sampled data)	`Observation.value as Quantity \| Observation.value as SampledData`
value-string	string	The value of the observation, if the value is a string, and also searches in CodeableConcept.text	`Observation.value as string \| Observation.value as CodeableConcept.text`
code-value-concept	composite	Code and coded value parameter pair	`Observation`
code-value-date	composite	Code and date/time value parameter pair	`Observation`
code-value-quantity	composite	Code and quantity value parameter pair	`Observation`
code-value-string	composite	Code and string value parameter pair	`Observation`
combo-code-value-concept	composite	Code and coded value parameter pair, including in components	`Observation.component`
combo-code-value-quantity	composite	Code and quantity value parameter pair, including in components	`Observation.component`
component-code-value-concept	composite	Component code and component coded value parameter pair	`Observation.component`
component-code-value-quantity	composite	Component code and component quantity value parameter pair	`Observation.component`

Observations are a central element in healthcare, used to support diagnosis, monitor progress, determine baselines and patterns and even capture demographic characteristics. Most observations are simple name/value pair assertions with some metadata, but some observations group other observations together logically, or even are multi-component observations.

Common Use Cases

Vital Signs
- Body weight
- Blood pressure
- Temperature
Laboratory Data
- Blood glucose
- Estimated GFR
Imaging Results
- Bone density
- Fetal measurements
Clinical Findings*
- Abdominal tenderness
Device Measurements
- EKG data
- Pulse Oximetry data
Clinical Assessment Tools
- APGAR score
- Glasgow Coma Score
Personal and Social Information
- Personal characteristics (e.g., eye color)
- Social history (e.g., tobacco use, family support)
- Core characteristics (e.g., pregnancy status, death assertion)

*Note: The boundaries between clinical findings and disorders remains a challenge in medical ontology. These boundaries can be clarified by profiling Observation for a particular use case.

Boundaries and Relationships

Primary Purpose

Observation is intended for capturing measurements and subjective point-in-time assessments
Supports name-value pairs or structured collections of name-value pairs

Instead of Observation, use these specialized resources when appropriate:

Resource Type	Use Case
AllergyIntolerance	Patient allergies
MedicationStatement	Medications taken by patient
FamilyMemberHistory	Patient's family history
Procedure	Procedure information
QuestionnaireResponse	Answers to questions
Condition	Clinical diagnoses
ClinicalImpression	Clinical assessments
Media	Audio, video, or image data
DiagnosticReport	Laboratory, pathology, and imaging reports

Special Considerations

Relationship with DiagnosticReport

DiagnosticReport provides clinical context for a set of observations
DiagnosticReport includes:
- Additional clinical context
- Atomic results
- Images and imaging reports
- Textual and coded interpretation
- Formatted representations
Observation is referenced by DiagnosticReport for atomic results

Edge Cases

Overlapping Scenarios
- Some data could fit multiple resources (e.g., illicit drug use could be MedicationStatement or Observation)
- Convention and common practice often guide the choice
Legacy Data
- When importing HL7 v2 data, specialized observations may appear in this resource due to limited source information
- This is considered appropriate use of Observation
Implementation Guidance
- If uncertain about appropriate use, consult with implementers on chat.fhir.org implementer's stream

Referenced Elements

This resource is referenced by: