^A06
ADT^A06 — Change Outpatient to Inpatient
Sent when a patient's status changes from outpatient (or emergency) to inpatient. The encounter class is upgraded and the patient is assigned a bed. This combines a change-of-class with a location update in a single message.
When Is This Sent?
When an ED patient is admitted to an inpatient unit, or when an outpatient observation patient is converted to a full inpatient admission. PV1.2 changes from O or E to I.
Real-World Usage
A06 is common in ED-heavy hospitals where patients often begin as outpatients (A04) and are subsequently admitted. Downstream systems that only process A01 for inpatient admissions will miss patients who were converted via A06. PACS, pharmacy, and billing must all handle A06 to ensure the patient's class and location are updated correctly.
Message Structure
Segment names link to their field-level reference pages.
| # | Segment | Purpose in this message | Req | Repeat |
|---|---|---|---|---|
| 1 | MSH | Message header with ADT^A06 in MSH.9 | R | — |
| 2 | EVN | Event type with A06 trigger and conversion timestamp | R | — |
| 3 | PID | Patient demographics | R | — |
| 4 | MRG | Prior visit identifier — the outpatient encounter being superseded | R | — |
| 5 | PV1 | Updated visit information with PV1.2=I and inpatient bed assignment | R | — |
| 6 | PV2 | Extended visit information | O | — |
| 7 | DG1 | Admitting diagnosis | O | Yes |
Example Message
Realistic example with fake patient data. Paste into the HL7 Message Viewer to explore interactively.
1MSH||^~\&|EPIC|HOSPITAL_A|MIRTH_PROD|PACS|20260310180000||ADT^A06^ADT_A06|MSG00035|P|2.5.1 2EVN||A06|20260310180000 3PID||1||234567^^^HOSP_A^MR||Johnson^Sarah^L||19920601|F 4MRG||234567^^^HOSP_A^MR||VIS20260310001^HOSP_A 5PV1||1|I|3C^310^1^^^HOSP_A||||5678^Wilson^Dr.^Sarah|||MED|||||ADM|||9012^Lee^Dr.^Amanda|IP||||||||||||||||||||||||||20260310090000
Troubleshooting Scenarios
Converted patient still shows as outpatient in downstream systems
Cause
Downstream systems are not subscribed to A06 events and never received the class change.
Fix
Add A06 to the event subscription for all downstream systems. Treat A06 like an admission update — downstream systems should update PV1.2 and PV1.3 (location) based on the message.
Duplicate inpatient encounter created alongside existing outpatient record
Cause
The downstream system processed A06 as a new admission rather than a conversion, because MRG was ignored or not mapped.
Fix
Ensure MRG segment handling is implemented. The receiving system should look up the prior visit using MRG.3 (prior visit number) and convert it rather than creating a new encounter.
Common Confusions
ADT^A06 (Outpatient to Inpatient) vs ADT^A02 (Transfer). A06 changes the patient class (O/E → I) and may also change the location. A02 only changes location — the patient class remains the same. Both update PV1.3, but A06 also changes PV1.2.
Related Message Types
Segment Reference
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