ADT^A24 — Link Patient Information

Two records appear to belong to the same patient, but a merge is not yet warranted: A24 creates a soft link, awaiting manual validation by identity vigilance.

Purpose

Typical case: probabilistic MPI matching that crosses a threshold without reaching certainty. Rather than blindly merging (A18/A40), the EMPI emits A24 to hold the records for human review by identity vigilance. No data is moved. The link will be promoted to A18/A40 if validated, or lifted by A37 (Unlink Patient Information) if disproven.

Segment structure

Structure ADT_A24: MSH, EVN, two PID blocks (linked patients), PD1 and PV1 optional.

Real-world example

MRN567890 and MRN567899 share name, given name and birth date — possible duplicate:

MSH|^~\&|HIS|HOSP01|EHR|CLINIC02|20260516162000||ADT^A24^ADT_A24|MSG00024001|P|2.5.1|||AL|NE
EVN|A24|20260516162000|||DRJONES^Jones^Sarah^^^DR.|SUSPECTED DUPLICATE - PENDING REVIEW
PID|1||MRN567890^^^HOSP^MR||DOE^JOHN^A^^MR.||19720515|M
PID|2||MRN567899^^^HOSP^MR||DOE^JOHN^A^^MR.||19720515|M

Acknowledgment (ACK)

MSH|^~\&|EHR|CLINIC02|HIS|HOSP01|20260516162001||ACK^A24^ACK|ACK00024001|P|2.5.1
MSA|AA|MSG00024001

Common errors

• A24 / A18 confusion: A24 erases NOTHING, it only signals. If the receiving EHR treats A24 as A18, a legitimate patient's identity can be lost.
• EVN-4 missing: no justification = no audit. Always provide the cause (MPI score, user request).
• A24 then silence: the link must be resolved (A18 merge validated OR A37 link lifted). Otherwise records are in limbo.

Related ADT events

See also: ADT^A18.