FHIR R4 Observation · US Core Laboratory Result Observation · US Core Vital Signs · US Core Clinical Result Observation

Observation covers three distinct kinds of data in the Patient Everything and Patient Summary bundles — laboratory results, vital signs, and the findings contained inside a DiagnosticReport. Each uses a different US Core profile and is documented separately below. It is not produced for Bulk Medication History.

Usage 1: Laboratory results

Laboratory Observation resources are top-level entries in the bundle, and are produced identically for both bundles.

Stable ID

The id is derived from the patient, the result date, the result code, the value, the unit, and the reference range (low, high, and text).

Fields

Field	Cardinality	Notes
`meta.profile`	1..1	Always set to the US Core Laboratory Result Observation profile URL.
`status`	1..1	Always `final`.
`category`	1..1	Always `laboratory` from the observation-category system.
`subject`	1..1	Reference to the Patient.
`effectiveDateTime`	1..1	The result date.
`code`	1..2	The result’s own coding, plus a second coding for the Connective Health panel classification when one applies — see Panel classification.
`value[x]`	0..1	See Result values.
`referenceRange`	0..1	See Reference ranges.
`performer`	0..1	Contained PractitionerRole built from the result’s provider and performing facility. Omitted when neither is known.

interpretation, specimen, issued, and note are not populated.

Result values

Source data	Published as
A value with a unit	`valueQuantity`, with the value and unit normalized to UCUM. The original unit text is preserved in `valueQuantity.unit`.
A value with no unit	`valueString`, carrying the raw source text — this covers qualitative results such as `POSITIVE` or `NEGATIVE`.
A value whose unit cannot be normalized to UCUM	Nothing. `value[x]` is left unset rather than published with an invalid unit.

Reference ranges

Source data	Published as
A numeric low and a numeric high	`referenceRange.low` and `referenceRange.high` as quantities.
A non-numeric or single-sided range	`referenceRange.text`, carrying the raw source text — this covers ranges such as `< 5.0` or `NEGATIVE`.
Neither	Nothing. `referenceRange` is omitted.

Panel classification

Where a result belongs to a Connective Health panel grouping, that grouping is published as an additional coding on code using the http://connectivehealth.io/fhir/panel-classification system. This is a Connective Health terminology, not a standard one, and is additive — the result’s own standard coding is always present as well.

Usage 2: Vital signs

Vital sign Observation resources are top-level entries in the bundle, and are produced identically for both bundles.

Only the vital signs in the table below are published. A vital sign recorded under any other LOINC code, or with no value or no date, is not included in either bundle.

Vital sign	LOINC code	Additional US Core profile
Blood pressure panel	`85354-9`	US Core Blood Pressure
Body height	`8302-2`	US Core Body Height
Body weight	`29463-7`	US Core Body Weight
Body temperature	`8310-5`	US Core Body Temperature
Body mass index	`39156-5`	US Core BMI
Heart rate	`8867-4`	US Core Heart Rate
Respiratory rate	`9279-1`	US Core Respiratory Rate
Oxygen saturation	`2708-6`, `59408-5`	US Core Pulse Oximetry

Stable ID

The id is derived from the patient, the observation date, the vital sign code, the value, and the unit.

Fields

Field	Cardinality	Notes
`meta.profile`	2..2	Always two profiles: the US Core Vital Signs profile, plus the specific profile for that vital sign from the table above.
`status`	1..1	Always `final`.
`category`	1..1	Always `vital-signs` from the observation-category system.
`subject`	1..1	Reference to the Patient.
`effectiveDateTime`	1..1	The observation date. Vital signs with no date are excluded entirely.
`code`	1..1	The vital sign’s LOINC coding. For a blood pressure panel this is fixed to LOINC `85354-9`, “Blood pressure panel with all children optional”.
`valueQuantity`	0..1	The measured value, normalized to UCUM, with the source unit preserved in `valueQuantity.unit`. Omitted for blood pressure panels, whose values live on `component` instead, and omitted when the value is not numeric.
`component`	0..2	Blood pressure only — see Blood pressure.
`performer`	0..1	Contained PractitionerRole built from the recording provider and facility. Omitted when neither is known.

Blood pressure

Blood pressure is always published as a panel rather than as two independent observations: one Observation coded 85354-9 with a systolic and a diastolic component.

Component	Notes
Systolic	`component.code` carries the source systolic coding (normally LOINC `8480-6`); `component.valueQuantity` uses UCUM `mm[Hg]` with a display unit of `mmHg`.
Diastolic	`component.code` carries the source diastolic coding (normally LOINC `8462-4`); same unit handling as systolic.

The panel’s effectiveDateTime and stable id are taken from the systolic reading.

Usage 3: Diagnostic report findings

Findings belonging to a DiagnosticReport are published as Observation resources contained inside that report and referenced from DiagnosticReport.result.

Stable ID

No id is assigned — these observations exist only inside their parent report and are neither addressable on their own nor deduplicated. Use the parent DiagnosticReport’s id to track them over time.

Fields

Field	Cardinality	Notes
`meta.profile`	1..1	Always set to the US Core Clinical Result Observation profile URL — note this differs from the laboratory profile above.
`status`	1..1	Always `final`.
`category`	1..1	Always `imaging` from the observation-category system.
`subject`	1..1	Reference to the Patient.
`effectiveDateTime`	1..1	The report date.
`code`	1..2	The report’s panel coding. In the Patient Everything bundle a panel classification coding is added where one applies; in the Patient Summary bundle it is never added.
`value[x]`	1..1	Either the discrete result value or the narrative report text — see below.
`referenceRange`	0..1	Populated on the discrete-value observation only, using the same rules as Reference ranges.
`performer`	0..1	Contained PractitionerRole built from the report’s provider and facility.

A report produces up to two contained observations, depending on what the source carries:

Source data	Contained observations
A discrete result value	One observation whose `value[x]` follows the same result value rules as laboratory results.
A narrative report text	One observation whose `valueString` is the report narrative.
Both	Two observations, one of each.
Neither	None — `DiagnosticReport.result` is empty.

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Observation

Usage 1: Laboratory results

Stable ID

Fields

Result values

Reference ranges

Panel classification

Usage 2: Vital signs

Stable ID

Fields

Blood pressure

Usage 3: Diagnostic report findings

Stable ID

Fields

​Usage 1: Laboratory results

​Stable ID

​Fields

​Result values

​Reference ranges

​Panel classification

​Usage 2: Vital signs

​Stable ID

​Fields

​Blood pressure

​Usage 3: Diagnostic report findings

​Stable ID

​Fields

Usage 1: Laboratory results

Stable ID

Fields

Result values

Reference ranges

Panel classification

Usage 2: Vital signs

Stable ID

Fields

Blood pressure

Usage 3: Diagnostic report findings

Stable ID

Fields