ADT^A02 — Transfer a Patient

An already-admitted patient moves bed, ward or facility: A02 propagates the new visit context to receivers without breaking the visit identifier.

Purpose

A02 fires when the patient moves between functional units: room change after a bed is freed, escalation to ICU, step-down to intermediate care, inter-service transfer. The visit number (PV1-19) stays stable; only PV1-3 (location) and PV1-10 (service) change.

A02 is not an administrative class change (that would be A06 / A07); it is a physical move within the same patient class.

Segment structure

Per chapter 3, abstract structure ADT_A02:

ADT_A02
  MSH                    Message Header (mandatory)
  [ SFT ]                Software Segment (optional)
  EVN                    Event Type (mandatory)
  PID                    Patient Identification (mandatory)
  [ PD1 ]                Patient Additional Demographics (optional)
  [ { ROL } ]            Role (optional, repeatable)
  PV1                    Patient Visit (mandatory)
  [ PV2 ]                Patient Visit - Additional Info (optional)
  [ { ROL } ]            Role (optional, repeatable)
  [ { DB1 } ]            Disability (optional, repeatable)
  [ { OBX } ]            Observation / Result (optional, repeatable)

MSH — Message Header

• MSH-9: ADT^A02^ADT_A02.
• MSH-10: unique message id within the sending HIS.
• MSH-11: P production, T test, D debug.

EVN — Event Type

• EVN-1: A02 (deprecated in v2.5+ but retained).
• EVN-2: HIS recording timestamp (CCYYMMDDHHMMSS).
• EVN-5: operator who recorded the transfer (XCN).
• EVN-6: real transfer timestamp (may differ from EVN-2 if recording is retroactive).

PID — Patient Identification

Identical PID structure as A01: patient identifier list (PID-3), name (PID-5), DOB (PID-7), administrative sex (PID-8), address (PID-11). Identity vigilance requires the PID carried in A02 to stay consistent with the PID of the A01 that opened the encounter.

PV1 — Patient Visit (key fields)

• PV1-3: new location (PL — Point of Care, Room, Bed, Facility).
• PV1-6: Prior Patient Location — the previous bed / ward. Used by receivers to compute length of stay per unit.
• PV1-10: new hospital service (table 0069).
• PV1-19: visit number — UNCHANGED from the originating A01.

Real-world example

Patient John A. Doe is transferred out of ICU 101 A to general medicine ward, room 205 B, after cardiac stabilisation:

MSH|^~\&|HIS|HOSP01|EHR|CLINIC02|20260515094530||ADT^A02^ADT_A02|MSG00004001|P|2.5.1|||AL|NE
EVN|A02|20260515094530|||DRJONES^Jones^Sarah^^^DR.
PID|1||MRN567890^^^HOSP^MR||DOE^JOHN^A^^MR.||19720515|M|||100 MAIN ST^^ANYTOWN^CA^90210^USA||(555)555-1234|||S||ACCT123456|123-45-6789
PV1|1|I|MED^205^B^HOSP01|EM|||DRSMITH^Smith^James^A^^DR.|||MED|||1|||DRSMITH^Smith^James^A^^DR.|ADM|||||||||||||||||||HOSP01|||||20260514102530||||||||ICU^101^A^HOSP01

• PV1-3: new location MED^205^B^HOSP01.
• PV1-6: prior location ICU^101^A^HOSP01.
• PV1-19: ACCT123456 — unchanged.

Acknowledgment (ACK)

MSH|^~\&|EHR|CLINIC02|HIS|HOSP01|20260515094531||ACK^A02^ACK|ACK00004001|P|2.5.1
MSA|AA|MSG00004001

Common errors

• PV1-19 changed: the visit number must NEVER change between A01 and A02, otherwise the receiver creates an orphan encounter.
• Missing PV1-6 (Prior Location): technically optional but used by every length-of-stay KPI.
• Transfer without preceding A01: A02 is invalid if the encounter does not exist. Always respect the A01 → A02* → A03 sequence.
• Simultaneous class change: if the move also flips outpatient → inpatient, use A06, not A02.

Related ADT events

See also: ADT^A01, ADT^A12, and FHIR Encounter.