HL7 OUL_R24 (Order-Oriented Observation) | Integration Soup HL7 Reference Guide

HL7 OUL_R24 Order-Oriented Observation

A lab result message where the order stays at the top and specimens hang beneath it.

HL7 message structure OUL_R24 groups and segments from HL7 v2.5.1 Hide structure

These are the generated groups and segments for the version selected at the top of the page. The article explains the workflow, and this panel follows the chosen HL7 version.

Message Structure

Segment	Name	Required	Repeatable
MSH	Message Header	Yes	No
SFT	Software Segment	No	Yes
NTE	Notes and Comments	No	No
OUL_R24.PIDPD1NTE_SUPPGRP	Pidpd1nte Suppgrp group	No	No
PID	Patient Identification	Yes	No
PD1	Patient Additional Demographic	No	No
NTE	Notes and Comments	No	Yes
OUL_R24.PV1PV2_SUPPGRP	Pv1pv2 Suppgrp group	No	No
PV1	Patient Visit	Yes	No
PV2	Patient Visit - Additional Information	No	No
OUL_R24.ORDER	Order group	Yes	Yes
OBR	Observation Request	Yes	No
ORC	Common Order	No	No
NTE	Notes and Comments	No	Yes
OUL_R24.TQ1TQ2_SUPPGRP	Tq1tq2 Suppgrp group	No	Yes
TQ1	Timing/Quantity	Yes	No
TQ2	Timing/Quantity Relationship	No	Yes
OUL_R24.SPMOBXSACINV_SUPPGRP	Spmobxsacinv Suppgrp group	No	Yes
SPM	Specimen	Yes	No
OBX	Observation/Result	No	Yes
OUL_R24.CONTAINER	Container group	No	Yes
SAC	Specimen Container detail	Yes	No
INV	Inventory Detail	No	No
OUL_R24.OBXTCDSIDNTE_SUPPGRP	Obxtcdsidnte Suppgrp group	No	Yes
OBX	Observation/Result	Yes	No
TCD	Test Code Detail	No	No
SID	Substance Identifier	No	Yes
NTE	Notes and Comments	No	Yes
CTI	Clinical Trial Identification	No	Yes
DSC	Continuation Pointer	No	No

OUL_R24 is an unsolicited laboratory observation message organized around the order. It still supports detailed specimen, container, inventory, and reagent information, but the order group comes first. That makes it useful when the receiver thinks primarily in orders while the lab still needs to report multi-specimen detail.

A classic example is a result that depends on more than one specimen or container. The order is the clinical thing being reported, but the specimen/container detail explains how the result was produced.

A small OUL_R24 example

MSH|^~\&|LABAUTO|CITYLAB|LIS|CITYLAB|20260715131500||OUL^R24^OUL_R24|OUL240001|P|2.5.1 PID|1||123456^^^CITYHOSP^MR||Smith^Jane^Anne^^Ms^^L||19800314|F PV1|1|O|LAB^DRAW^1^CITYHOSP||||12345^Careful^Clara OBR|1|ORD448812^EHR|LAB998878^CITYLAB|2160-0^Creatinine^LN|||20260715114500 SPM|1|SPEC20260715001^CITYLAB||BLD^Blood^HL70487|||||||||||||20260715114000 SAC|||TUBE778899^CITYLAB||||SER^Serum tube^L OBX|1|NM|2160-0^Creatinine^LN||86|umol/L|45-90|N|||F

What systems do with it

The sender is usually a LIS, analyzer manager, or lab automation platform. Receivers file the result under the order while preserving enough specimen/container detail for traceability, quality, and downstream review.

R24 is a good fit when the order is the primary filing object but the result has multi-specimen or container complexity. It avoids forcing everything into either a pure ORU-style order hierarchy or a pure specimen-first hierarchy.

How to read the structure

The message can include optional patient and visit groups, then one or more required order groups. Each order group starts with OBR and optional ORC, notes, and timing. Specimen groups below the order use SPM, specimen-level OBX, container groups with SAC and INV, and observation groups with OBX, TCD, SID, and NTE.

Implementation traps

Do not assume one order means one specimen. R24 exists partly because a clinically single result can depend on none, one, or many specimens and containers. If you collapse those details, document what was lost.

Also pay attention to where OBX appears. Some OBX segments describe specimen-level details, while others are the actual reported observations. Position and grouping matter.

Reference notes

The HL7 v2+ OUL_R24 page describes this as an order-oriented observation message for multi-specimen testing and notes support for non-patient samples, QC material, container inventory, and reagent/substance detail.