HL7 ADT Events

HL7 ADT (Admission, Discharge, Transfer) event codes are a crucial component of the Health Level Seven International (HL7) standards, which play a pivotal role in the healthcare industry's information exchange. These codes specifically facilitate the effective communication of patient admission, discharge, and transfer information between various healthcare systems.

These ADT event codes are up to date with HL7 2.8.2 standards. The event code should be sent in MSH-9.2 and EVN-1 (if EVN segment is sent).

ADT Codes

A01Admit/visit notification
A02Transfer a patient
A03Discharge/end visit
A04Register a patient
A05Pre-admit a patient
A06Change an outpatient to an inpatient
A07Change an inpatient to an outpatient
A08Update patient information
A09Patient departing - tracking
A10Patient arriving - tracking
A11Cancel admit/visit notification
A12Cancel transfer
A13Cancel discharge/end visit
A14Pending admit
A15Pending transfer
A16Pending discharge
A17Swap patients
A18Merge patient information
A19Patient query
A20Bed status update
A21Patient goes on a leave of absence
A22Patient returns from a leave of absence
A23Delete a patient record
A24Link patient information
A25Cancel pending discharge
A26Cancel pending transfer
A27Cancel pending admit
A28Add person information
A29Delete person information
A30Merge person information
A31Update person information
A32Cancel patient arriving - tracking
A33Cancel patient departing - tracking
A34Merge patient information - patient ID only
A35Merge patient information - account number only
A36Merge patient information - patient ID and account number
A37Unlink patient information
A38Cancel pre-admit
A39Merge person - patient ID
A40Merge patient - patient identifier list
A41Merge account - patient account number
A42Merge visit - visit number
A43Move patient information - patient identifier list
A44Move account information - patient account number
A45Move visit information - visit number
A46Change patient ID
A47Change patient identifier list
A48Change alternate patient ID
A49Change patient account number
A50Change visit number
A51Change alternate visit ID
A52Cancel leave of absence for a patient
A53Cancel patient returns from a leave of absence
A54Change attending doctor
A55Cancel change attending doctor
A60Update allergy information
A61Change consulting doctor
A62Cancel change consulting doctor

Most Important ADT Event Codes

While there are over 60 ADT event codes, not all of them have equal significance in modern healthcare systems. Based on my experience, here's a list of the most important ADT event codes to know, and why they're important.

  • A01: admiting a patient is key event, and along with it the PV1-44 admit date.
  • A02: transfering a patient to a new location is important for understanding where patients are. It's also important to understand where the correct transfer date & time is in the message as well - often the EVN-2.
  • A03: discharging a patient is another key event, and along with it the PV1-45 discharge date.
  • A08: "update patient information" should be a relatively straightforward and unimportant, but some health information systems use A08's as a sort of "catchall" due to system design or end-user error. For example, an A08 may need to be considered the same as an A08 if the patient location given is different from the previous!
  • A11/A12: cancel admit & cancel transfers can have big implications downstream if you're working with an application that needs to track patient movements.