<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="observation-va" />
  <url value="http://vha.gov/fhir/StructureDefinition/observation-va" />
  <version value="1.0" />
  <name value="observation-va" />
  <status value="draft" />
  <date value="2018-09-19" />
  <description value="A profile on the HL7 FHIR Observation resource.  Intended to represent measurements and simple assertions made about a patient." />
  <fhirVersion value="3.0.1" />
  <kind value="resource" />
  <abstract value="false" />
  <type value="Observation" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation" />
  <derivation value="constraint" />
  <snapshot />
  <differential>
    <element id="Observation">
      <path value="Observation" />
      <definition value="A profile on the HL7 FHIR Observation resource.  Intended to represent measurements and simple assertions made about a patient.   Adds the following extensions and constraints to the base HL7 Observation resource:&#xD;&#xA;- Proximal-provenance-extension:  Denotes the most recent source of the documented information&#xD;&#xA;- Presence-indicator-extension:  Denotes whether the observation is present, absent, or indeterminate.  Used to formalize negation for Observations&#xD;&#xA;- Adds additional allowed values for the &quot;category&quot; element&#xD;&#xA;- Constrains the &quot;code&quot; element to values from SNOMED-CT and LOINC only.  This applies equally to top-level codes, as well as codes denoted within nested components.&#xD;&#xA;- Constrains values that are CodeableConcepts to be coded in SNOMED-CT, LOINC, and RxNorm only.  This applies equally to top-level values, as well as values denoted within nested components.&#xD;&#xA;- Constrains values that are Quantities to be coded in UCUM only.  This applies equally to top-level values, as well as values denoted within nested components.&#xD;&#xA;- Requires &quot;bodySite&quot; element to be populated with values from the SNOMED-CT Body Structures hierarchy (value set http://hl7.org/fhir/ValueSet/body-site)" />
    </element>
    <element id="Observation.extension">
      <path value="Observation.extension" />
      <slicing>
        <discriminator>
          <type value="value" />
          <path value="url" />
        </discriminator>
        <rules value="open" />
      </slicing>
    </element>
    <element id="Observation.extension:proximal-provenance-extension">
      <path value="Observation.extension" />
      <sliceName value="proximal-provenance-extension" />
      <type>
        <code value="Extension" />
        <profile value="http://vha.gov/fhir/StructureDefinition/proximal-provenance-extension" />
      </type>
      <mustSupport value="true" />
    </element>
    <element id="Observation.extension:presence-indicator-extension">
      <path value="Observation.extension" />
      <sliceName value="presence-indicator-extension" />
      <definition value="Indicates whether a condition is present, absent, or indeterminate.  Used to support formal negation of problems and disorders encoded using the us-core-problem-va profile or the observation-va profile." />
      <comment value="The presenceIndScope component designates the path(s) of the data element(s) in the resource instance to which the presenceIndValue applies.&#xD;&#xA;The presenceIndValue component indicates whether whether the information collectively designated by the presenceIndScope value is &quot;present&quot;, &quot;absent&quot;, or &quot;indeterminate&quot;" />
      <type>
        <code value="Extension" />
        <profile value="http://vha.gov/fhir/StructureDefinition/presence-indicator-extension" />
      </type>
      <mustSupport value="true" />
    </element>
    <element id="Observation.category">
      <path value="Observation.category" />
      <definition value="A code that classifies the general type of observation being made.  Has been extended in this profile to include &quot;History of present illness,&quot; to allow for the recording of patient signs and symptoms." />
      <requirements value="Used for filtering what observations are retrieved and displayed, as well as the clinical context in which observations were collected/generated." />
      <min value="1" />
      <max value="1" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="ObservationCategory" />
        </extension>
        <strength value="required" />
        <description value="Codes for high level observation categories" />
        <valueSetReference>
          <reference value="http://vha.gov/fhir/ValueSet/observation-category" />
        </valueSetReference>
      </binding>
    </element>
    <element id="Observation.category.coding">
      <path value="Observation.category.coding" />
      <min value="1" />
      <max value="1" />
    </element>
    <element id="Observation.code">
      <path value="Observation.code" />
      <definition value="Describes what was observed. Sometimes this is called the observation &quot;name&quot;.  The value may represent a clinical concept that is an observation unto itself (such as 'rash' or 'shortness of breath'), or it may represent an attribute that requires a value in the 'value[x]' element to make up the observation (such as 'attribute=color of conjunctiva' and 'value=yellow')" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="ObservationCode" />
        </extension>
        <strength value="required" />
        <valueSetReference>
          <reference value="http://vha.gov/fhir/ValueSet/observation-code" />
        </valueSetReference>
      </binding>
    </element>
    <element id="Observation.value[x]">
      <path value="Observation.value[x]" />
      <short value="Actual result, if the observation has one" />
      <definition value="The value of the observed attribute, if the observation is structured as an attribute/value pair." />
      <comment value="Normally, observations structured as attribute/value pairs will have either a single value or a set of related observations encoded within nested components or referenced Observation instances. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. This element has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueString, valueBoolean, valueRange, valueRatio, valueSampledData, valueAttachment, valueTime, valueDateTime, or valuePeriod. (The name format is &quot;'value' + the type name&quot; with a capital on the first letter of the type).&#xD;&#xD;&#xD;If the data element is usually coded or if the type associated with the Observation.value defines a coded value, use CodeableConcept instead of string datatype even if the value is uncoded text.  A value set is bound to the ValueCodeableConcept element.    For further discussion and examples see the  [notes section](observation.html#notes) below." />
      <requirements value="If the Observation is structured as an attribute/value pair, the observation must have a value, though it may not if it is in error, if a value is not yet available (e.g., for a lab test), or if the value is represented as a group of observations (such as systolic and diastolic blood pressures), in which case the values may be represented within nested components or other referenced Observation instances." />
      <type>
        <code value="CodeableConcept" />
        <profile value="http://vha.gov/fhir/StructureDefinition/observation-value-codeable-concept" />
      </type>
      <type>
        <code value="Quantity" />
        <profile value="http://vha.gov/fhir/StructureDefinition/observation-value-quantity" />
      </type>
      <type>
        <code value="CodeableConcept" />
      </type>
      <type>
        <code value="string" />
      </type>
      <type>
        <code value="Range" />
      </type>
      <type>
        <code value="Ratio" />
      </type>
      <type>
        <code value="SampledData" />
      </type>
      <type>
        <code value="Attachment" />
      </type>
      <type>
        <code value="time" />
      </type>
      <type>
        <code value="dateTime" />
      </type>
      <type>
        <code value="Period" />
      </type>
    </element>
    <element id="Observation.bodySite">
      <path value="Observation.bodySite" />
      <definition value="Indicates the site on the subject's body where the observation was made (i.e. the target site).  In this profile, must be populated with values from the SNOMED-CT Body Structures hierarchy (value set http://hl7.org/fhir/ValueSet/body-site)" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="BodySite" />
        </extension>
        <strength value="required" />
        <valueSetReference>
          <reference value="http://hl7.org/fhir/ValueSet/body-site" />
        </valueSetReference>
      </binding>
    </element>
    <element id="Observation.component.extension">
      <path value="Observation.component.extension" />
      <slicing>
        <discriminator>
          <type value="value" />
          <path value="url" />
        </discriminator>
        <rules value="open" />
      </slicing>
    </element>
    <element id="Observation.component.extension:presence-indicator-extension">
      <path value="Observation.component.extension" />
      <sliceName value="presence-indicator-extension" />
      <definition value="Indicates whether a condition is present, absent, or indeterminate.  Used to support formal negation of problems and disorders encoded using the us-core-problem-va profile or the observation-va profile." />
      <comment value="The presenceIndScope component designates the path(s) of the data element(s) in the resource instance to which the presenceIndValue applies.&#xD;&#xA;The presenceIndValue component indicates whether whether the information collectively designated by the presenceIndScope value is &quot;present&quot;, &quot;absent&quot;, or &quot;indeterminate&quot;" />
      <type>
        <code value="Extension" />
        <profile value="http://vha.gov/fhir/StructureDefinition/presence-indicator-extension" />
      </type>
      <mustSupport value="true" />
    </element>
    <element id="Observation.component.code">
      <path value="Observation.component.code" />
      <definition value="Describes what was observed. Sometimes this is called the component &quot;name&quot;.  The value may represent a clinical concept that is an observation unto itself (such as 'rash' or 'shortness of breath'), or it may represent an attribute that requires a value in the 'value[x]' element to make up the observation (such as 'attribute=color of conjunctiva' and 'value=yellow')" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="ObservationCode" />
        </extension>
        <strength value="extensible" />
        <valueSetUri value="http://vha.gov/fhir/ValueSet/observation-code" />
      </binding>
    </element>
    <element id="Observation.component.value[x]">
      <path value="Observation.component.value[x]" />
      <short value="Actual component result, if the component has one" />
      <definition value="The value of the observed attribute, if the component is structured as an attribute/value pair." />
      <requirements value="If the component is structured as an attribute/value pair, the component must have a value, though it may not if it is in error or a value is not yet available (e.g., for a lab test)." />
      <type>
        <code value="CodeableConcept" />
        <profile value="http://vha.gov/fhir/StructureDefinition/observation-value-codeable-concept" />
      </type>
      <type>
        <code value="Quantity" />
        <profile value="http://vha.gov/fhir/StructureDefinition/observation-value-quantity" />
      </type>
      <type>
        <code value="CodeableConcept" />
      </type>
      <type>
        <code value="string" />
      </type>
      <type>
        <code value="Range" />
      </type>
      <type>
        <code value="Ratio" />
      </type>
      <type>
        <code value="SampledData" />
      </type>
      <type>
        <code value="Attachment" />
      </type>
      <type>
        <code value="time" />
      </type>
      <type>
        <code value="dateTime" />
      </type>
      <type>
        <code value="Period" />
      </type>
    </element>
  </differential>
</StructureDefinition>