For a full list of available versions, see the Directory of published versions
4.2.2. Patient Unmerge
Patient Unmerge provides a RESTful approach to separating managed patient identities within PCR that were previously merged and have subsequently been determined to represent different individuals. In a Patient Unmerge request, the patient identities and associated merge relationships to be reversed are provided to PCR, which validates the request and evaluates the proposed unmerge using identity management, source authority, governance, and stewardship rules. PCR assesses the historical merge relationships and determines how the affected patient identities should be restored while applying established identity management policies.
4.2.2.1. Usage
In the PCR Patient Unmerge operation, the request must contain a Parameters resource that identifies the managed patient identities to be separated and the merge relationships to be removed. PCR evaluates the unmerge request to ensure it complies with approved governance controls, stewardship requirements, and identity management policies. Upon successful validation, PCR restores the affected managed patient identities, re-establishes the appropriate identity relationships, preserves source contributions, lineage, and audit history, and maintains traceability of the unmerge action in accordance with established policies. The result is the accurate representation of distinct patient identities while maintaining a trusted, governed, and auditable patient registry that supports reliable patient identification across connected healthcare organizations.
POST: Patient Unmerge
Actor: Contributor
Role: Submits a Patient Unmerge operation request to the PCR.
Actor: PCR
Role: Receives, authenticates, validates, and unmerges patients.
4.2.2.2. Specification
Patient Unmerge Request
Patient Unmerge Input Parameters
The update interaction is performed by an HTTP POST command as shown:
POST [base-submit]/Patient/$unmerge
Patient Unmerge Response
Patient Unmerge Output Parameters
Example Patient Unmerge Request
HTTP Method:
POST
Headers:
Content-Type: application/fhir+json
Address:
[base-submit]/Patient/$unmerge
Message Body:
{
"id": "parameters-unmerge-input-example",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/profile-parameters-unmerge-input"
]
},
{
"name": "merged-patient",
"reference": "Patient/patient-contribution-merged-example"
}
},
{
"name": "restore-patient",
"reference": "Patient/patient-contribution-source-example"
}
},
{
"name": "prior-merge-id",
"system": "https://ehealthontario.ca/fhir/NamingSystem/pcr-merge-event-id",
"value": "MERGE-20260806-00001"
}
},
{
"name": "unmerge-reason",
{
"system": "https://ehealthontario.ca/fhir/CodeSystem/pcr-unmerge-reason",
"code": "incorrect-merge",
}
],
"text": "Prior merge was determined to be incorrect following governed identity review."
}
},
{
"name": "unmerge-requester",
"system": "https://hospital.example.ca/user-id",
}
}
]
}
Response Body:
{
"id": "parameters-unmerge-output-example",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/profile-parameters-unmerge-output"
]
},
{
"id": "parameters-unmerge-input-example",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/profile-parameters-unmerge-input"
]
},
{
"name": "merged-patient",
"reference": "Patient/patient-contribution-merged-example"
}
},
{
"name": "restore-patient",
"reference": "Patient/patient-contribution-source-example"
}
},
{
"name": "prior-merge-id",
"system": "https://ehealthontario.ca/fhir/NamingSystem/pcr-merge-event-id",
"value": "MERGE-20260806-00001"
}
},
{
"name": "unmerge-reason",
{
"system": "https://ehealthontario.ca/fhir/CodeSystem/pcr-unmerge-reason",
"code": "incorrect-merge",
}
],
"text": "Prior merge was determined to be incorrect following governed identity review."
}
},
{
"name": "unmerge-requester",
"system": "https://hospital.example.ca/user-id",
}
}
]
}
},
{
"name": "operation-outcome",
"id": "operationoutcome-example-success",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/pcr-operationoutcome-contribution"
]
},
{
"text": "Prior merge MERGE-20260806-00001 was reversed. Patient/patient-contribution-source-example was restored and Patient/patient-contribution-target-example remains active as a separate identity."
}
}
]
}
},
{
"name": "retained-patient-result",
"id": "patient-contribution-target-example",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/profile-patient-contribution"
]
},
{
{
"system": "http://terminology.hl7.org/CodeSystem/v2-0203",
}
]
},
"system": "https://hospital.example.ca/mrn",
}
],
{
],
{
{
"url": "http://hl7.org/fhir/StructureDefinition/iso21090-EN-qualifier",
}
]
},
null
]
}
],
]
}
},
{
"name": "restored-patient-result",
"id": "patient-contribution-source-example",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/profile-patient-contribution"
]
},
{
{
"system": "http://terminology.hl7.org/CodeSystem/v2-0203",
}
]
},
"system": "https://hospital.example.ca/mrn",
}
],
{
],
{
{
"url": "http://hl7.org/fhir/StructureDefinition/iso21090-EN-qualifier",
}
]
},
null
]
}
],
]
}
}
]
}
Example Validation Failure
HTTP Response: 400 Bad Request
Message Body:
{
"id": "operationoutcome-example-unmerge-error",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/pcr-operationoutcome-contribution"
]
},
{
"text": "merged-patient, restore-patient, and prior-merge-id are required for an unmerge request."
},
"Parameters.parameter.where(name = 'merged-patient')",
"Parameters.parameter.where(name = 'restore-patient')",
"Parameters.parameter.where(name = 'prior-merge-id')"
]
}
]
}
Example Patient Not Found
HTTP Response: 404 Not Found
Message Body:
{
"id": "operationoutcome-example-notfound",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/pcr-operationoutcome-contribution"
]
},
{
"text": "No Patient resource was found for id 987654."
},
]
}
]
}
Example Business-Rule Conflict
HTTP Response: 409 Conflict
Message Body:
{
"id": "operationoutcome-example-unmerge-conflict",
"http://ontariohealth.ca/fhir/pcr/StructureDefinition/pcr-operationoutcome-contribution"
]
},
{
"text": "The requested unmerge cannot be completed because the prior merge event is not eligible for reversal under PCR governance rules."
}
}
]
}
4.2.2.3. Supported Profiles
Patient Unmerge Input Parameters
Patient Unmerge Output Parameters
4.2.2.4. Expected Behavior
| Outcome |
Header HTTP Response |
Payload OperationOutcome |
Expected Handling |
| Unmerge completed |
200 OK |
Yes |
Return unmerge status, retained patient reference, restored patient reference, and optional informational OperationOutcome. |
| Unmerge accepted for review |
202 Accepted |
Yes |
|
| Validation failure |
400 Bad Request |
Yes |
Return computable validation details when required unmerge inputs are missing or malformed. |
| Merge relationship not found |
404 Not Found |
Yes |
Indicate that the prior merge event or referenced Patient record could not be resolved. |
| Unauthorized |
401 Unauthorized or 403 Forbidden |
No |
|
| Governance or identity conflict |
409 Conflict |
No |
Indicate that PCR unmerge governance rules prevent the requested reversal. |
| Service failure |
5xx Server Error |
No |
|
