description: This profile sets minimum expectations for an Observation resource to record, search, and fetch observations of gestational age by scan, or gestational age by last menstrual period (LMP) with standard coding and units. It is based on the core FHIR [Observation](http://hl7.org/fhir/R4/observation.html) resource and identifies the *additional* mandatory core elements, extensions, vocabularies and value sets that **SHALL** be present in the Observation resource when conforming to this profile. It provides the floor for standards development for specific uses cases in an Australian context.
package_name: hl7.fhir.au.core
derivation: constraint
name: AUCoreGestationalAge
type: Observation
elements:
  category: {mustSupport: true, index: 1}
  value[x]:
    elements:
      value: {index: 23}
      unit: {index: 24}
      system:
        pattern: {type: Uri, value: 'http://unitsofmeasure.org'}
        index: 25
      code:
        pattern: {type: Code, value: d}
        index: 26
    required: [value, unit]
  encounter:
    type: Reference
    mustSupport: true
    refers: ['http://hl7.org.au/fhir/core/StructureDefinition/au-core-encounter']
    index: 15
  valueQuantity: {type: Quantity, mustSupport: true, choiceOf: value, index: 22}
  value:
    mustSupport: true
    choices: [valueQuantity]
    index: 21
  effectiveDateTime:
    constraint:
      au-core-obs-01: {human: Date shall be at least to day, source: 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-gestationalage', severity: error, expression: $this is DateTime implies $this.toString().length() >= 10}
    short: Date, and optionally time, the observation was performed
    type: dateTime
    mustSupport: true
    choiceOf: effective
    index: 18
  status:
    pattern: {type: Code, value: final}
    mustSupport: true
    index: 0
  effective:
    constraint:
      au-core-obs-01: {human: Date shall be at least to day, source: 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-gestationalage', severity: error, expression: $this is DateTime implies $this.toString().length() >= 10}
    short: Date, and optionally time, the observation was performed
    mustSupport: true
    choices: [effectiveDateTime]
    index: 17
  code:
    mustSupport: true
    pattern:
      type: CodeableConcept
      value:
        coding:
        - {code: '57036006', system: 'http://snomed.info/sct'}
    index: 2
    elements:
      coding:
        index: 3
        slicing:
          rules: open
          discriminator:
          - {path: code, type: value}
          - {path: system, type: value}
          min: null
          slices:
            loincGestationalAge:
              match: {code: 18185-9, system: 'http://loinc.org'}
              schema:
                short: LOINC Gestational Age
                index: 4
                elements:
                  system:
                    pattern: {type: Uri, value: 'http://loinc.org'}
                    index: 5
                  code:
                    pattern: {type: Code, value: 18185-9}
                    index: 6
                required: [system, code]
            loincGestationalAgeByLMP:
              match: {code: 11885-1, system: 'http://loinc.org'}
              schema:
                short: LOINC Gestational Age by Last Menstrual Period (LMP)
                index: 7
                elements:
                  system:
                    pattern: {type: Uri, value: 'http://loinc.org'}
                    index: 8
                  code:
                    pattern: {type: Code, value: 11885-1}
                    index: 9
                required: [system, code]
            loincGestationalAgeByScan:
              match: {code: 11888-5, system: 'http://loinc.org'}
              schema:
                short: LOINC Gestational Age By Scan
                index: 10
                elements:
                  system:
                    pattern: {type: Uri, value: 'http://loinc.org'}
                    index: 11
                  code:
                    pattern: {type: Code, value: 11888-5}
                    index: 12
                required: [system, code]
  focus: {short: The fetus, index: 14}
  subject:
    type: Reference
    short: The pregnant individual
    mustSupport: true
    refers: ['http://hl7.org/fhir/StructureDefinition/Patient']
    index: 13
  performer:
    type: Reference
    mustSupport: true
    refers: ['http://hl7.org.au/fhir/core/StructureDefinition/au-core-organization', 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-patient', 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-practitioner', 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-practitionerrole', 'http://hl7.org.au/fhir/core/StructureDefinition/au-core-relatedperson']
    index: 19
  dataAbsentReason: {mustSupport: true, index: 27}
package_version: 0.2.2-preview
class: profile
kind: resource
url: http://hl7.org.au/fhir/core/StructureDefinition/au-core-gestationalage
base: http://hl7.org/fhir/StructureDefinition/Observation
version: 0.2.2-preview
required: [effectiveDateTime, subject, category, effective]