ADT^A11 — Cancel Admit / Visit Notification

The admission should never have happened: A11 cancels an erroneous A01, propagates cancellation to all receivers and releases the allocated resources.

Purpose

A11 is the pure cancellation of an A01 that should never have been emitted: data entry mistake, patient redirected before effective admission, identity error. The encounter is cancelled, not closed: no length of stay, no DRG, no billing.

All downstream systems must delete or void the visit: beds released, orders cancelled, lab tests retracted. LIS and pharmacy systems typically reject orders whose source visit has been cancelled by A11.

Segment structure

ADT_A09 (structure shared by A11/A12/A13)
  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)
  [ { DB1 } ]            Disability (optional, repeatable)
  [ { OBX } ]            Observation (optional, repeatable)

MSH — EVN

• MSH-9: ADT^A11^ADT_A09 — note the ADT_A09 structure shared with A12 and A13.
• EVN-2: cancellation entry timestamp.
• EVN-3: Date/Time Planned Event — may carry the originating A01 timestamp to ease matching on the receiver side.
• EVN-5: operator who recorded the cancellation.

PID — PV1

PID and PV1 carry the data of the encounter being cancelled: patient name, MRN, visit number. The receiver matches on PV1-19 to identify the visit to remove.

A11 vs A03

Real-world example

Cancel an A01 entered at 10:25, cancelled at 10:55 (identity mistake):

MSH|^~\&|HIS|HOSP01|EHR|CLINIC02|20260514105500||ADT^A11^ADT_A09|MSG00009001|P|2.5.1|||AL|NE
EVN|A11|20260514105500|20260514102530||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|ICU^101^A^HOSP01|EM|||DRSMITH^Smith^James^A^^DR.|||CAR|||1|||DRSMITH^Smith^James^A^^DR.|ADM|||||||||||||||||||HOSP01|||||20260514102530

Acknowledgment (ACK)

MSH|^~\&|EHR|CLINIC02|HIS|HOSP01|20260514105501||ACK^A11^ACK|ACK00009001|P|2.5.1
MSA|AA|MSG00009001

Common errors

• A11 after clinical activity has started: if acts have been coded, A11 may create inconsistencies with the LIS and billing. Prefer A03 + accounting adjustment.
• A11 with a different PV1-19: must match the visit number of the originating A01, otherwise the encounter to cancel stays a ghost.
• A11 on a merged encounter (post-A40): classic identity-vigilance trap — pinpointing the right encounter to cancel becomes ambiguous.

Related ADT events

See also: ADT^A01 and ADT^A13.