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ADT^A01

HL7 v2 trigger event, Chapter 3 Patient Administration, admissions management.

Definition

A01 signals that a patient is admitted to inpatient care and a new visit (PV1-19 Visit Number) is opened. The message uses the ADT_A01 abstract structure: MSH, EVN, PID, PV1 plus optional segments (NK1, AL1, DG1). It is the pivot of the encounter lifecycle, later followed by transfers (A02) and discharge (A03).

Origin

Defined in HL7 v2.5.1, Chapter 3 "Patient Administration", published by HL7 International.

Example in context

MSH|^~\&|HIS|HOSP01|EHR|CLINIC02|20260518||ADT^A01^ADT_A01|MSG001|P|2.5.1
EVN|A01|20260518
PID|1||MR1001^^^HOSP^MR||DUBOIS^CLAIRE
PV1|1|I|3WEST^301^A|...|||VN20260518

  • PV1 — visit segment carrying the Visit Number.
  • EVN — ADT event segment.

Last updated: June 20, 2026