Message type

Population / location-based laboratory order

Submits a population or location-based laboratory order for surveillance or public health testing. The ORC and OBR segments define the order, and SPM identifies the specimen source and collection site.

57segments

22required

10groups

v2.9HL7 version

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OPL^O37^OPL_O37|MSG001|P|2.9\r' \
      'PID|1||MRN-10045||SMITH^JOHN||19850315|M\r' \
      'SPM|1||BLD^Blood|VENOUS'

# .. 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
specimen_type = msg.spm.specimen_type
specimen_id = msg.spm.specimen_id

Python examples

Build and parse OPL^O37 messages in Python

How to construct, send, receive, and extract fields from real-world OPL^O37 messages.

Parse an incoming OPL^O37 message

Demonstrates receiving and extracting key fields from a population / location-based laboratory order transaction

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OPL^O37^OPL_O37|MSG001|P|2.9\r' \
      'PID|1||MRN-10045||SMITH^JOHN||19850315|M\r' \
      'SPM|1||BLD^Blood|VENOUS'

# .. 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
specimen_type = msg.spm.specimen_type
specimen_id = msg.spm.specimen_id

Tutorials

Learn by building

Step-by-step guides for working with HL7 v2 in Zato.

MLLP

Receive and parse HL7 v2 messages

Set up an MLLP channel, parse incoming messages, and respond with acknowledgments.

Start tutorial Build

Build and send HL7 v2 messages

Construct HL7 v2 messages from scratch using typed segment classes and send them over MLLP.

Start tutorial

FAQ

Frequently asked questions

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||OPL^O37^OPL_O37|MSG00001|P|2.9\rPRT|1||AT^Attending||1234^CHEN^DAVID^L^^^MD'
msg = HL7Message.parse(raw)

name = msg.pid.patient_name
dob = msg.pid.date_time_of_birth

Beyond the mandatory MSH header, the required segments are: PRT, GT1, NK1, PID, OBX, IN1, SPM, OBX. 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.

Reference

OPL^O37 segment composition

Segments that make up the OPL^O37 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	`NTE`	Optional	Yes	Notes and comments	-
6	`PRT`	Required	Yes	Participation information	-
7	`GT1`	Required	No	Guarantor	GUARANTOR
8	`NTE`	Optional	Yes	Notes and comments	GUARANTOR
9	`NK1`	Required	Yes	Next of kin / associated parties	ORDER
10	`PID`	Required	No	Patient identification	ORDER
11	`PD1`	Optional	No	Patient additional demographic	ORDER
12	`PRT`	Optional	Yes	Participation information	ORDER
13	`ARV`	Optional	Yes	Access restriction	ORDER
14	`OBX`	Required	No	Observation result	OBSERVATIONS_ON_PATIENT
15	`PRT`	Optional	Yes	Participation information	OBSERVATIONS_ON_PATIENT
16	`IN1`	Required	No	Insurance	INSURANCE
17	`IN2`	Optional	No	Insurance additional info	INSURANCE
18	`IN3`	Optional	No	Insurance additional info - certification	INSURANCE
19	`AL1`	Optional	Yes	Patient allergy information	ORDER
20	`SPM`	Required	No	Specimen	ORDER
21	`OBX`	Required	No	Observation result	SPECIMEN_OBSERVATION
22	`PRT`	Optional	Yes	Participation information	SPECIMEN_OBSERVATION
23	`SAC`	Required	No	Specimen container detail	CONTAINER
24	`OBX`	Required	No	Observation result	CONTAINER
25	`PRT`	Optional	Yes	Participation information	CONTAINER
26	`ORC`	Required	No	Common order	OBSERVATION_REQUEST
27	`PRT`	Optional	Yes	Participation information	OBSERVATION_REQUEST
28	`OBR`	Required	No	Observation request	OBSERVATION_REQUEST
29	`PRT`	Optional	Yes	Participation information	OBSERVATION_REQUEST
30	`TQ1`	Required	No	Timing / quantity	OBSERVATION_REQUEST
31	`TQ2`	Optional	Yes	Timing / quantity relationship	OBSERVATION_REQUEST
32	`TCD`	Optional	No	Test code detail	OBSERVATION_REQUEST
33	`DG1`	Optional	Yes	Diagnosis	OBSERVATION_REQUEST
34	`OBX`	Required	No	Observation result	OBSERVATION_REQUEST
35	`PRT`	Optional	Yes	Participation information	OBSERVATION_REQUEST
36	`SGH`	Optional	No	Segment group header	ORDER
37	`NK1`	Required	Yes	Next of kin / associated parties	ORDER
38	`PID`	Required	No	Patient identification	PATIENT_PRIOR
39	`PD1`	Optional	No	Patient additional demographic	PATIENT_PRIOR
40	`PRT`	Optional	Yes	Participation information	PATIENT_PRIOR
41	`ARV`	Optional	Yes	Access restriction	PATIENT_PRIOR
42	`PV1`	Required	No	Patient visit	PATIENT_VISIT_PRIOR
43	`PV2`	Optional	No	Patient visit - additional info	PATIENT_VISIT_PRIOR
44	`PRT`	Optional	Yes	Participation information	PATIENT_VISIT_PRIOR
45	`AL1`	Optional	No	Patient allergy information	ORDER
46	`OBR`	Required	No	Observation request	ORDER_PRIOR
47	`ORC`	Optional	No	Common order	ORDER_PRIOR
48	`PRT`	Required	No	Participation information	ORDER_PRIOR
49	`DEV`	Optional	Yes	Device	ORDER_PRIOR
50	`TQ1`	Required	No	Timing / quantity	ORDER_PRIOR
51	`TQ2`	Optional	Yes	Timing / quantity relationship	ORDER_PRIOR
52	`OBX`	Required	No	Observation result	ORDER_PRIOR
53	`PRT`	Optional	Yes	Participation information	ORDER_PRIOR
54	`SGT`	Optional	No	Segment group trailer	ORDER
55	`FT1`	Optional	Yes	Financial transaction	ORDER
56	`CTI`	Optional	Yes	Clinical trial identification	ORDER
57	`BLG`	Optional	No	Billing	ORDER

Ready to build integrations?

Get started with Zato and connect your systems in minutes.

Get started ▶Read the docs

Open source In Python