Message type

Unsolicited laboratory observation - order based

Delivers unsolicited laboratory observation results. The OBR segment defines the observation request and OBX segments carry individual result values. Laboratory information systems send this to deliver results to ordering providers.

46segments

14required

5groups

v2.9HL7 version

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OUL^R24^OUL_R24|MSG001|P|2.9\r' \
      'OBR|1||ORD001\r' \
      'OBX|1|NM|2345-7^Glucose^LN||95|mg/dL|70-100'

# .. parsed into a Python object ..
msg = HL7Message.parse(raw)

# .. whose fields we can now access.
order_id = msg.obr.placer_order_number
test = msg.obr.universal_service_identifier
value = msg.obx.observation_value
units = msg.obx.units

Python examples

Build and parse OUL^R24 messages in Python

How to construct, send, receive, and extract fields from real-world OUL^R24 messages.

Parse an incoming OUL^R24 message

Demonstrates receiving and extracting key fields from a unsolicited laboratory observation - order based transaction

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OUL^R24^OUL_R24|MSG001|P|2.9\r' \
      'OBR|1||ORD001\r' \
      'OBX|1|NM|2345-7^Glucose^LN||95|mg/dL|70-100'

# .. parsed into a Python object ..
msg = HL7Message.parse(raw)

# .. whose fields we can now access.
order_id = msg.obr.placer_order_number
test = msg.obr.universal_service_identifier
value = msg.obx.observation_value
units = msg.obx.units

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||OUL^R24^OUL_R24|MSG00001|P|2.9\rNK1|1|JOHNSON^MICHAEL|SPO^Spouse|100 Oak Lane^^Portland^OR^97201|5035551234\rDSC|CONT-001'
msg = HL7Message.parse(raw)

order_id = msg.obr.placer_order_number
test = msg.obr.universal_service_identifier

Beyond the mandatory MSH header, the required segments are: PID, OBX, PV1, OBR, ORC, OBX, TXA, TQ1. 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

OUL^R24 segment composition

Segments that make up the OUL^R24 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	No	Notes and comments	-
6	`PID`	Required	No	Patient identification	PATIENT
7	`PD1`	Optional	No	Patient additional demographic	PATIENT
8	`PRT`	Optional	Yes	Participation information	PATIENT
9	`OH1`	Optional	Yes	Employment status	PATIENT
10	`OH2`	Optional	Yes	Past or present job	PATIENT
11	`OH3`	Optional	No	Usual work	PATIENT
12	`OH4`	Optional	Yes	Combat zone work	PATIENT
13	`ARV`	Optional	Yes	Access restriction	PATIENT
14	`NTE`	Optional	Yes	Notes and comments	PATIENT
15	`OBX`	Required	No	Observation result	PATIENT
16	`PRT`	Optional	Yes	Participation information	PATIENT
17	`PV1`	Required	No	Patient visit	PATIENT
18	`PV2`	Optional	No	Patient visit - additional info	PATIENT
19	`PRT`	Optional	Yes	Participation information	PATIENT
20	`NK1`	Optional	Yes	Next of kin / associated parties	-
21	`OBR`	Required	No	Observation request	ORDER
22	`PRT`	Optional	Yes	Participation information	ORDER
23	`ORC`	Required	No	Common order	ORDER
24	`PRT`	Optional	Yes	Participation information	ORDER
25	`OBX`	Required	No	Observation result	ORDER_DOCUMENT
26	`PRT`	Optional	Yes	Participation information	ORDER_DOCUMENT
27	`TXA`	Required	No	Transcription document header	ORDER_DOCUMENT
28	`NTE`	Optional	Yes	Notes and comments	ORDER
29	`PRT`	Optional	Yes	Participation information	ORDER
30	`TQ1`	Required	No	Timing / quantity	ORDER
31	`TQ2`	Optional	Yes	Timing / quantity relationship	ORDER
32	`SPM`	Required	No	Specimen	ORDER
33	`OBX`	Required	No	Observation result	SPECIMEN_OBSERVATION
34	`PRT`	Optional	Yes	Participation information	SPECIMEN_OBSERVATION
35	`SAC`	Required	No	Specimen container detail	CONTAINER
36	`INV`	Optional	No	Inventory detail	CONTAINER
37	`OBX`	Required	No	Observation result	ORDER
38	`PRT`	Optional	Yes	Participation information	ORDER
39	`TCD`	Optional	No	Test code detail	ORDER
40	`SID`	Optional	Yes	Substance identifier	ORDER
41	`INV`	Optional	Yes	Inventory detail	ORDER
42	`NTE`	Optional	Yes	Notes and comments	ORDER
43	`CTI`	Optional	Yes	Clinical trial identification	ORDER
44	`DEV`	Required	No	Device	ORDER
45	`OBX`	Optional	Yes	Observation result	ORDER
46	`DSC`	Optional	No	Continuation pointer	-

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