Message type

Laboratory order response - multiple orders per container (to OML_O35)

Acknowledges and responds to the corresponding order message with acceptance, modification, or rejection details. The MSA segment reports the status and ORC segments echo the original order control information. Fulfilling systems send this back to the ordering system.

20segments

9required

5groups

v2.9HL7 version

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'ORL^O55^ORL_O55|MSG001|P|2.9\r' \
      'ORC|NW|ORD001||GRP001|||1^BID\r' \
      'OBR|1||ORD001'

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

# .. whose fields we can now access.
order_control = msg.orc.order_control
order_number = msg.orc.placer_order_number
order_id = msg.obr.placer_order_number
test = msg.obr.universal_service_identifier

Python examples

Build and parse ORL^O55 messages in Python

How to construct, send, receive, and extract fields from real-world ORL^O55 messages.

Parse an incoming ORL^O55 message

Demonstrates receiving and extracting key fields from a laboratory order response - multiple orders per container (to oml_o35) transaction

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'ORL^O55^ORL_O55|MSG001|P|2.9\r' \
      'ORC|NW|ORD001||GRP001|||1^BID\r' \
      'OBR|1||ORD001'

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

# .. whose fields we can now access.
order_control = msg.orc.order_control
order_number = msg.orc.placer_order_number
order_id = msg.obr.placer_order_number
test = msg.obr.universal_service_identifier

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||ORL^O55^ORL_O55|MSG00001|P|2.9\rMSA|AA|MSG00001\rERR|||0|I|'
msg = HL7Message.parse(raw)

order_control = msg.orc.order_control
order_number = msg.orc.placer_order_number

Beyond the mandatory MSH header, the required segments are: MSA, PID, SPM, OBX, SAC, ORC, TQ1, OBR. 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

ORL^O55 segment composition

Segments that make up the ORL^O55 message, in order. Groups are shown with their child segments.

#	Segment	Usage	Repeats	Description	Group
1	`MSH`	Required	No	Message header	-
2	`MSA`	Required	No	Message acknowledgment	-
3	`ARV`	Optional	Yes	Access restriction	-
4	`ERR`	Optional	Yes	Error	-
5	`SFT`	Optional	Yes	Software segment	-
6	`UAC`	Optional	No	User authentication credential	-
7	`NTE`	Optional	Yes	Notes and comments	-
8	`PID`	Required	No	Patient identification	RESPONSE
9	`PRT`	Optional	Yes	Participation information	RESPONSE
10	`SPM`	Required	No	Specimen	RESPONSE
11	`OBX`	Required	No	Observation result	SPECIMEN_OBSERVATION
12	`PRT`	Optional	Yes	Participation information	SPECIMEN_OBSERVATION
13	`NTE`	Optional	Yes	Notes and comments	RESPONSE
14	`SAC`	Required	No	Specimen container detail	SPECIMEN_CONTAINER
15	`ORC`	Required	No	Common order	SPECIMEN_CONTAINER
16	`PRT`	Optional	Yes	Participation information	SPECIMEN_CONTAINER
17	`TQ1`	Required	No	Timing / quantity	TIMING
18	`TQ2`	Optional	Yes	Timing / quantity relationship	TIMING
19	`OBR`	Required	No	Observation request	OBSERVATION_REQUEST
20	`PRT`	Optional	Yes	Participation information	OBSERVATION_REQUEST

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