Message type

Blood product order

Submits a blood product order to the blood bank. The ORC carries order control and BPO defines the requested blood product type and quantity.

31segments

8required

2groups

v2.9HL7 version

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OMB^O27^OMB_O27|MSG001|P|2.9\r' \
      'ORC|NW|ORD001||GRP001|||1^BID\r' \
      'BPO|1|O+^O Positive^ABO|3|ML|300'

# .. 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
product = msg.bpo.bp_universal_service_identifier
quantity = msg.bpo.bp_quantity

Python examples

Build and parse OMB^O27 messages in Python

How to construct, send, receive, and extract fields from real-world OMB^O27 messages.

Parse an incoming OMB^O27 message

Demonstrates receiving and extracting key fields from a blood product order transaction

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'OMB^O27^OMB_O27|MSG001|P|2.9\r' \
      'ORC|NW|ORD001||GRP001|||1^BID\r' \
      'BPO|1|O+^O Positive^ABO|3|ML|300'

# .. 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
product = msg.bpo.bp_universal_service_identifier
quantity = msg.bpo.bp_quantity

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||OMB^O27^OMB_O27|MSG00001|P|2.9'
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: PID, PV1, IN1, ORC, TQ1, BPO, 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

OMB^O27 segment composition

Segments that make up the OMB^O27 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	`PID`	Required	No	Patient identification	PATIENT
7	`PD1`	Optional	No	Patient additional demographic	PATIENT
8	`PRT`	Optional	Yes	Participation information	PATIENT
9	`ARV`	Optional	Yes	Access restriction	PATIENT
10	`NTE`	Optional	Yes	Notes and comments	PATIENT
11	`PV1`	Required	No	Patient visit	PATIENT
12	`PV2`	Optional	No	Patient visit - additional info	PATIENT
13	`PRT`	Optional	Yes	Participation information	PATIENT
14	`IN1`	Required	No	Insurance	PATIENT
15	`IN2`	Optional	No	Insurance additional info	PATIENT
16	`IN3`	Optional	No	Insurance additional info - certification	PATIENT
17	`GT1`	Optional	No	Guarantor	PATIENT
18	`AL1`	Optional	Yes	Patient allergy information	PATIENT
19	`ORC`	Required	No	Common order	ORDER
20	`PRT`	Optional	Yes	Participation information	ORDER
21	`TQ1`	Required	No	Timing / quantity	ORDER
22	`TQ2`	Optional	Yes	Timing / quantity relationship	ORDER
23	`BPO`	Required	No	Blood product order	ORDER
24	`SPM`	Optional	No	Specimen	ORDER
25	`NTE`	Optional	Yes	Notes and comments	ORDER
26	`DG1`	Optional	Yes	Diagnosis	ORDER
27	`OBX`	Required	No	Observation result	ORDER
28	`PRT`	Optional	Yes	Participation information	ORDER
29	`NTE`	Optional	Yes	Notes and comments	ORDER
30	`FT1`	Optional	Yes	Financial transaction	ORDER
31	`BLG`	Optional	No	Billing	ORDER

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