## On this page

Measurements and simple assertions made about a patient, device or other subject. US Core Profiles related to Observations are as follows:

- [US Core Laboratory Result profile](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-us-core-observation-lab.html)
- [US Core Smoking Status Observation profile](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-us-core-smokingstatus.html).
- [US Core Pulse Oximetry Profile](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-us-core-pulse-oximetry.html)
- [US Core Pediatric BMI for Age Profile](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-pediatric-bmi-for-age.html)
- [US Core Pediatric Weight for Height](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-pediatric-weight-for-height.html)
- [US Core Pediatric Head Circumference](https://hl7.org/fhir/us/core/stu3.1.1/StructureDefinition-head-occipital-frontal-circumference-percentile.html)
- [US Core Observation Survey](http://hl7.org/fhir/us/core/StructureDefinition-us-core-observation-survey.html)
- [US Core Observation Social History](http://hl7.org/fhir/us/core/StructureDefinition-us-core-observation-social-history.html)
- [US Core Clinical Test Result](http://hl7.org/fhir/us/core/StructureDefinition-us-core-observation-clinical-test.html)
- [US Core Observation Sexual Orientation](http://hl7.org/fhir/us/core/StructureDefinition-us-core-observation-sexual-orientation.html)

## Elements

| Name | Required | Type | Description |
| --- | --- | --- | --- |
| identifier |  | [Identifier](/content/docs/api/fhir/datatypes/identifier/index.html)[] | Business Identifier for observation<br>Details<br>A unique identifier assigned to this observation. |
| basedOn |  | Reference< [CarePlan](/content/docs/api/fhir/resources/careplan/index.html)<br> | | [DeviceRequest](/content/docs/api/fhir/resources/devicerequest/index.html)<br> | | [ImmunizationRecommendation](/content/docs/api/fhir/resources/immunizationrecommendation/index.html)<br> | | [MedicationRequest](/content/docs/api/fhir/resources/medicationrequest/index.html)<br> | | [NutritionOrder](/content/docs/api/fhir/resources/nutritionorder/index.html)<br> | | [ServiceRequest](/content/docs/api/fhir/resources/servicerequest/index.html) >[] | Fulfills plan, proposal or order<br>Details<br>A plan, proposal or order that is fulfilled in whole or in part by this event. For example, a MedicationRequest may require a patient to have laboratory test performed before it is dispensed. |
| partOf |  | Reference< [MedicationAdministration](/content/docs/api/fhir/resources/medicationadministration/index.html)<br> | | [MedicationDispense](/content/docs/api/fhir/resources/medicationdispense/index.html)<br> | | [MedicationStatement](/content/docs/api/fhir/resources/medicationstatement/index.html)<br> | | [Procedure](/content/docs/api/fhir/resources/procedure/index.html)<br> | | [Immunization](/content/docs/api/fhir/resources/immunization/index.html)<br> | | [ImagingStudy](/content/docs/api/fhir/resources/imagingstudy/index.html) >[] | Part of referenced event<br>Details<br>A larger event of which this particular Observation is a component or step. |
| status | ✓ | code | registered | preliminary | final | amended +<br>Details<br>The status of the result value.<br>This element is labeled as a modifier because the status contains codes that mark the resource as not currently valid. |
| category |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html)[] | Classification of type of observation<br>Details<br>A code that classifies the general type of observation being made. |
| code | ✓ | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Type of observation (code / type)<br>Details<br>Describes what was observed. Sometimes this is called the observation "name". |
| subject |  | Reference< [Patient](/content/docs/api/fhir/resources/patient/index.html)<br> | | [Group](/content/docs/api/fhir/resources/group/index.html)<br> | | [Device](/content/docs/api/fhir/resources/device/index.html)<br> | | [Location](/content/docs/api/fhir/resources/location/index.html) > | Who and/or what the observation is about<br>Details<br>The patient, or group of patients, location, or device this observation is about and into whose record the observation is placed. |
| focus |  | Reference<Resource>[] | What the observation is about, when it is not about the subject of record<br>Details<br>The actual focus of an observation when it is not the patient of record representing something or someone associated with the patient such as a spouse, parent, fetus, or donor. |
| encounter |  | Reference< [Encounter](/content/docs/api/fhir/resources/encounter/index.html) > | Healthcare event during which this observation is made<br>Details<br>The healthcare event (e.g. a patient and healthcare provider interaction) during which this observation is made. |
| effective[x] |  | dateTime, [Period](/content/docs/api/fhir/datatypes/period/index.html), [Timing](/content/docs/api/fhir/datatypes/timing/index.html), instant | Clinically relevant time/time-period for observation<br>Details<br>The time or time-period the observed value is asserted as being true. |
| issued |  | instant | Date/Time this version was made available<br>Details<br>The date and time this version of the observation was made available to providers. |
| performer |  | Reference< [Practitioner](/content/docs/api/fhir/resources/practitioner/index.html)<br> | | [PractitionerRole](/content/docs/api/fhir/resources/practitionerrole/index.html)<br> | | [Organization](/content/docs/api/fhir/resources/organization/index.html)<br> | | [CareTeam](/content/docs/api/fhir/resources/careteam/index.html)<br> | | [Patient](/content/docs/api/fhir/resources/patient/index.html)<br> | | [RelatedPerson](/content/docs/api/fhir/resources/relatedperson/index.html) >[] | Who is responsible for the observation<br>Details<br>Who was responsible for asserting the observed value as "true". |
| value[x] |  | [Quantity](/content/docs/api/fhir/datatypes/quantity/index.html), [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html), string, boolean, integer, [Range](/content/docs/api/fhir/datatypes/range/index.html), [Ratio](/content/docs/api/fhir/datatypes/ratio/index.html), [SampledData](/content/docs/api/fhir/datatypes/sampleddata/index.html), time, dateTime, [Period](/content/docs/api/fhir/datatypes/period/index.html) | Actual result<br>Details<br>The information determined as a result of making the observation. |
| dataAbsentReason |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Why the result is missing<br>Details<br>Provides a reason why the expected value in the element Observation.value[x] is missing. |
| interpretation |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html)[] | High, low, normal, etc.<br>Details<br>A categorical assessment of an observation value. |
| note |  | [Annotation](/content/docs/api/fhir/datatypes/annotation/index.html)[] | Comments about the observation<br>Details<br>Comments about the observation or the results. |
| bodySite |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Observed body part<br>Details<br>Indicates the site on the subject's body where the observation was made. |
| method |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | How it was done<br>Details<br>Indicates the mechanism used to perform the observation. |
| specimen |  | Reference< [Specimen](/content/docs/api/fhir/resources/specimen/index.html) > | Specimen used for this observation<br>Details<br>The specimen that was used when this observation was made. |
| device |  | Reference< [Device](/content/docs/api/fhir/resources/device/index.html) | | [DeviceMetric](/content/docs/api/fhir/resources/devicemetric/index.html) > | (Measurement) Device<br>Details<br>The device used to generate the observation data. |
| referenceRange |  | ObservationReferenceRange[] | Provides guide for interpretation<br>Details<br>Guidance on how to interpret the value by comparison to a normal or recommended range. |
| id |  | string | Unique id for inter-element referencing<br>Details<br>Unique id for the element within a resource. |
| extension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Additional content defined by implementations<br>Details<br>May be used to represent additional information that is not part of the basic definition of the element. |
| modifierExtension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Extensions that cannot be ignored even if unrecognized<br>Details<br>May be used to represent additional information that is not part of the basic definition of the element. |
| low |  | [Quantity](/content/docs/api/fhir/datatypes/quantity/index.html) | Low Range, if relevant<br>Details<br>The value of the low bound of the reference range. |
| high |  | [Quantity](/content/docs/api/fhir/datatypes/quantity/index.html) | High Range, if relevant<br>Details<br>The value of the high bound of the reference range. |
| type |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Reference range qualifier<br>Details<br>Codes to indicate the what part of the targeted reference population it applies to. |
| appliesTo |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html)[] | Reference range population<br>Details<br>Codes to indicate the target population this reference range applies to. |
| age |  | [Range](/content/docs/api/fhir/datatypes/range/index.html) | Applicable age range, if relevant<br>Details<br>The age at which this reference range is applicable. |
| text |  | string | Text based reference range in an observation<br>Details<br>Text based reference range in an observation. |
| hasMember |  | Reference< [Observation](/content/docs/api/fhir/resources/observation/index.html)<br> | | [QuestionnaireResponse](/content/docs/api/fhir/resources/questionnaireresponse/index.html)<br> | | [MolecularSequence](/content/docs/api/fhir/resources/molecularsequence/index.html) >[] | Related resource that belongs to the Observation group<br>Details<br>This observation is a group observation that includes the target as a member of the group. |
| derivedFrom |  | Reference< [DocumentReference](/content/docs/api/fhir/resources/documentreference/index.html)<br> | | [ImagingStudy](/content/docs/api/fhir/resources/imagingstudy/index.html)<br> | | [Media](/content/docs/api/fhir/resources/media/index.html)<br> | | [QuestionnaireResponse](/content/docs/api/fhir/resources/questionnaireresponse/index.html)<br> | | [Observation](/content/docs/api/fhir/resources/observation/index.html)<br> | | [MolecularSequence](/content/docs/api/fhir/resources/molecularsequence/index.html) >[] | Related measurements the observation is made from<br>Details<br>The target resource that represents a measurement from which this observation value is derived. |
| component |  | ObservationComponent[] | Component results<br>Details<br>Some observations have multiple component observations. |
| id |  | string | Unique id for inter-element referencing<br>Details<br>Unique id for the element within a resource. |
| extension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Additional content defined by implementations<br>Details<br>May be used to represent additional information that is not part of the basic definition of the element. |
| modifierExtension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Extensions that cannot be ignored even if unrecognized<br>Details<br>May be used to represent additional information that is not part of the basic definition of the element. |
| code | ✓ | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Type of component observation (code / type)<br>Details<br>Describes what was observed. |
| value[x] |  | [Quantity](/content/docs/api/fhir/datatypes/quantity/index.html), [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html), string, boolean, integer, [Range](/content/docs/api/fhir/datatypes/range/index.html), [Ratio](/content/docs/api/fhir/datatypes/ratio/index.html), [SampledData](/content/docs/api/fhir/datatypes/sampleddata/index.html), time, dateTime, [Period](/content/docs/api/fhir/datatypes/period/index.html) | Actual component result<br>Details<br>The information determined as a result of making the observation. |
| dataAbsentReason |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html) | Why the component result is missing<br>Details<br>Provides a reason why the expected value in the element Observation.component.value[x] is missing. |
| interpretation |  | [CodeableConcept](/content/docs/api/fhir/datatypes/codeableconcept/index.html)[] | High, low, normal, etc.<br>Details<br>A categorical assessment of an observation value. |
| referenceRange |  | [] | Provides guide for interpretation of component result<br>Details<br>Guidance on how to interpret the value by comparison to a normal or recommended range. |

## Search Parameters

| Name | Type | Description | Expression |
| --- | --- | --- | --- |
| code | token | The code of the observation type | Observation.code |
| date | date | Obtained date/time | Observation.effective |
| identifier | token | The unique id for a particular observation | Observation.identifier |
| patient | reference | The subject that the observation is about | 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-value-concept | token | The value or component value of the observation, if the value is a CodeableConcept | Observation.value.ofType(CodeableConcept) | Observation.component.value.ofType(CodeableConcept) |
| component-code | token | The component code of the observation type | Observation.component.code |
| component-value-concept | token | The value of the component observation, if the value is a CodeableConcept | Observation.component.value.ofType(CodeableConcept) |
| 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 |
| 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.ofType(CodeableConcept) |
| value-date | date | The value of the observation, if the value is a date or period of time | Observation.value.ofType(dateTime) | Observation.value.ofType(Period)
| value-quantity | quantity | The value of the observation, if the value is a Quantity | Observation.value.ofType(Quantity) |
| code-value-concept | composite | Code and coded value parameter pair | Observation |
| component-code-value-concept | composite | Component code and component coded value parameter pair | Observation.component |

## Inherited Elements

| Name | Required | Type | Description |
| --- | --- | --- | --- |
| id |  | string | Logical id of this artifact<br>Details<br>The logical id of the resource, as used in the URL for the resource. |
| meta |  | [Meta](/content/docs/api/fhir/datatypes/meta/index.html) | Metadata about the resource<br>Details<br>The metadata about the resource. |
| implicitRules |  | uri | A set of rules under which this content was created<br>Details<br>A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. |
| language |  | code | Language of the resource content<br>Details<br>The base language in which the resource is written. |
| text |  | [Narrative](/content/docs/api/fhir/datatypes/narrative/index.html) | Text summary of the resource, for human interpretation<br>Details<br>A human-readable narrative that contains a summary of the resource. |
| contained |  | Resource[] | Contained, inline Resources<br>Details<br>These resources do not have an independent existence apart from the resource that contains them. |
| extension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Additional content defined by implementations<br>Details<br>May be used to represent additional information that is not part of the basic definition of the resource. |
| modifierExtension |  | [Extension](/content/docs/api/fhir/datatypes/extension/index.html)[] | Extensions that cannot be ignored<br>Details<br>May be used to represent additional information that is not part of the basic definition of the resource.