An A21 event is sent to notify systems that an admitted patient has left the healthcare institution temporarily. It is used for systems in which a bed is still assigned to the patient, and it puts the current admitted patient activities on hold. For example, it is used to notify dietary services and laboratory systems when the patient goes home for the weekend.
The fields included when this message is sent should be the fields pertinent to communicate this event. When other important fields change it is recommended that the A08 (update patient information) event be used instead.
ADT ADT Message Chapter
MSH Message Header 2
EVN Event Type 3
PID Patient Identification 3
[PD1] Additional Demographics 3
PV1 Patient Visit 3
[ PV2 ] Patient Visit - Additional Info. 3
[ { DB1 } ] Disability Information 3
[ { OBX } ] Observation/Result 7
ACK General Acknowledgment Chapter
MSH Message Header 2
MSA Message Acknowledgment 2
[ ERR ] Error 2