Changes the visit number associated with a patient encounter. The PID segment identifies the patient and MRG carries the prior visit number. Systems that track encounters by visit number consume this to update their references.
# Zato
from zato.hl7v2 import HL7Message
# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
'ADT^A50^ADT_A50|MSG001|P|2.9\r' \
'PID|1||MRN-10045||SMITH^JOHN||19850315|M\r' \
'PV1|1|I|MED^201^A'
# .. parsed into a Python object ..
msg = HL7Message.parse(raw)
# .. whose fields we can now access.
name = msg.pid.patient_name
dob = msg.pid.date_time_of_birth
patient_class = msg.pv1.patient_class
location = msg.pv1.assigned_patient_locationHow to construct, send, receive, and extract fields from real-world ADT^A50 messages.
Demonstrates receiving and extracting key fields from a change visit number transaction
# Zato
from zato.hl7v2 import HL7Message
# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
'ADT^A50^ADT_A50|MSG001|P|2.9\r' \
'PID|1||MRN-10045||SMITH^JOHN||19850315|M\r' \
'PV1|1|I|MED^201^A'
# .. parsed into a Python object ..
msg = HL7Message.parse(raw)
# .. whose fields we can now access.
name = msg.pid.patient_name
dob = msg.pid.date_time_of_birth
patient_class = msg.pv1.patient_class
location = msg.pv1.assigned_patient_locationStep-by-step guides for working with HL7 v2 in Zato.
Use the HL7v2 message parser to extract the typed structure. The parsed message gives you direct access to every segment and field by name.
from zato.hl7v2 import HL7Message
raw = 'MSH|^~\&|SENDER|FACILITY|RECEIVER|DEST|20260401120000||ADT^A50^ADT_A50|MSG00001|P|2.9\rEVN|A50|20260401120000\rPID|1||MRN-10045||JOHNSON^SARAH^M||19880612|F|||100 Oak Lane^^Portland^OR^97201\rPD1|||Family Health Clinic^^12345\rMRG|MRN-OLD-001\rPV1|1|I|MED^201^A^^^MAIN||||1234^CHEN^DAVID^L^^^MD|5678^PATEL^NINA^R^^^MD|||MED|||||||VN-90001|||||||||||||||||||||20260401'
msg = HL7Message.parse(raw)
name = msg.pid.patient_name
dob = msg.pid.date_time_of_birthBeyond the mandatory MSH header, the required segments are: EVN, PID, MRG, PV1. Optional segments provide additional detail when available.
Zato connects to any system that speaks HL7v2 over MLLP or FHIR over REST. This includes Epic, Cerner, Meditech, Allscripts, and other EHR platforms.
Yes, Zato has built-in MLLP support for sending and receiving HL7v2 messages. MLLP channels handle the framing protocol automatically.
Zato supports HL7 v2.9, which is backward compatible with earlier versions including v2.3, v2.5, and v2.7. Standard segments and datatypes are available as typed Python classes.
Yes. Zato handles both HL7v2 and FHIR natively, so you can parse v2 messages and build FHIR resources with IG-specific extensions in the same service. Typed Python classes are available for both protocols, including extensions from US Core, UK Core, Da Vinci, and other Implementation Guides.
Segments that make up the ADT^A50 message, in order. Groups are shown with their child segments.
| # | Segment | Usage | Repeats | Description | Group |
|---|---|---|---|---|---|
| 1 | MSH | Required | No | Message header | - |
| 2 | ARV | Optional | Yes | Access restriction | - |
| 3 | SFT | Optional | Yes | Software segment | - |
| 4 | UAC | Optional | No | User authentication credential | - |
| 5 | EVN | Required | No | Event type | - |
| 6 | PID | Required | No | Patient identification | - |
| 7 | PD1 | Optional | No | Patient additional demographic | - |
| 8 | MRG | Required | No | Merge patient information | - |
| 9 | PV1 | Required | No | Patient visit | - |
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