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4.1 Purpose

This section describes the transaction set required for sending structured patient-oriented clinical data from one computer system to another. A common use of these transaction sets will be to transmit observations and results of diagnostic studies from the producing system (e.g., clinical 4.4.1.4.1  laboratory system, Radiology system) (the filler), to the ordering syste4.4.1.25 OBR-25 Result status (ID) 00258m (system (e.g., GP Surgery, specialists office system) (the placer). However, the transaction set is not limited to such transactions. Observations can be sent from producing systems to archival medical record systems (not necessarily the order placer) and from such medical record systems to other systems that were not part of the ordering loop, e.g., an office practice system of the referring physician for inpatient test results ordered by an inpatient surgeon. These transaction sets permit the transmission of any kind of clinical observations including (but not limited to) clinical laboratory results, the results of imaging studies (excluding the image), Pulmonary function studies, measures of patient status and condition, vital signs, intake and output, severity and/or frequency of symptoms, drug allergies, problem lists, diagnostic lists, physician and nursing history, physicals, progress notes, operative notes and so on. An observation can be one of many data types. The main ones are text, numbers and codes. This provides the flexibility needed to transmit observations that are recorded as continuous values (e.g., glucose, diastolic blood pressure), as categorical values, e.g., patient position (sitting, reclining or standing), VDRL (reactive, weakly reactive or nonreactive), or as text. An entire History and Physical could be transmitted as an observation whose value is one large chunk of formatted text. In this Australian guide however, we foprogressed logical model,cus on Laboratory results.

This section provides mechanisms for transmitting structured, record-oriented reports. This means that individual observations are transmitted as separate logical entities (objects), and within this entity, separate fields are defined for identifying the observation, its values, its units, normal ranges, etc., such that the receiving system can “understand,” reorganize and/or react to the contents of these messages. 

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Observations are usually ordered and reported as sets (batteries) of many separate observations. Physicians order electrolytes (consisting of sodium, potassium, chloride, bicarbonate) or vitals (consisting of diastolic blood pressure, systolic blood pressure, pulse, and temperature). Moreover, tests that we may think of as single entity, e.g., cardiac echo, usually yield multiple separate measurements, e.g., left ventricular diameter, left atrial diameter, etc. Moreover, observations that are usually reported as text (e.g., the review of systems from the history and physical) can also be considered a set of separately analyzable analysable units (e.g., cardiac history, pulmonary history, genito-urinary history, etc.). We strongly suggest that all text clinical reports be broken down into such separate analyzable separate analysable entities and that these individual entities be transmitted as separate OBX segments. Because many attributes of a set of observations taken at one time will be identical, one OBR segment serves as a header for the report and carries the information that applies to all of the individual observations in the set. In the case of ordered observations, the OBR segment is a “turn-around document” like the manual request forms it replaces. It carries information about the order to the producing service; a copy of the OBR with additional fields completed is returned with the observations to the requesting service. Not all observations are preceded by an order. However, all observations whether explicitly ordered or initiated without an order are reported with an OBR segment as the report header.

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The triggering events that follow are all served by the ORU (Observational report – Unsolicited) or the ORF (Observational Report Response) messages in combination with ACK and QRY. Only the ORU messsage message is covered in the Australian localisation and some of the optional segments have been removed.

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The ORU^R01 message is sent out by the laboratory and in respose response a ACK^R01 message should be produced to confirm receipt of the ORU message. The structure of the ACK message is as below:

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The OBR segments confirm the status and completion of the ordered tests back to the placer allowing the placer to check off each test ordered as it is received. The OBR segments do not contain the results or when the results will be available. However, the structure of the OBR and OBX segments in the ORU can reflect the specimen used to determine the results e.g. specimen ID. 

HL7 Attribute Table – OBR – Observation Request 

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OBR-28 Repeat is NOT restricted to 5 copy doctors in this specification as it is in the HL7 International specification.

4.4.1.1 OBR-1 Set ID - OBR (SI) 00237 

Definition: For the first order transmitted, the sequence number shall be 1; for the second order, it shall be 2; and so on.  This field is required if more than one OBR segment is sent with the order.

4.4.1.2 OBR-2 Placer order number (EI) 00216 

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Since third party providers at another site (those other than the placer and filler of an order) can send and receive ORM and ORR messages (ie i.e. create orders), the placer site ID in this field may not be the same as any sending and receiving HDs  (as identified in the MSH segment).

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Note: The field length of 250 characters is a variation to the HL7 International standard which has a length of 22 characters.

Placer order numbers are not specifically required in patient referralsoptional in patient referral messages (but OBR-3 Filler Order number below are required).

4.4.1.3 OBR-3 Filler order number (EI) 00217

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Definition: This field is the order number associated with the filling application. It is a case of the Entity Identifier data type (See Datatypes, “EI - Entity Identifier”). Its first component is a string that identifies an order detail segment (e.g., OBR). It is assigned by the order filler application. This string must uniquely identify the order (as specified in the order detail segment) from other orders in a particular filling application (e.g., clinical laboratory). This uniqueness must persist over time. The second through fourth components contain the filler original authoring filler site ID, in the form of the HD data type (see Datatypes, “HD - hierarchic designator”). The second component of the filler order number always identifies the actual filler of an order. Since third party sites/applications (those other than the placer and filler of an order) can send and receive ORM and ORR messages, the filler application ID in this field may not be the same as any sending and receiving application HDs (as identified in the MSH segment).

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Note: The field length of 250 characters is a variation to the HL7 International standard which has a length of 22 characters.

Clinical referrals are not orders and in the referral context the originator of the referral is designated the filler.

The "filler" is the clinical application which Messages other than order messages must have the filler order number present and must qualify the identifier using the site identifier (HD components: namespace, universal id, universal ID type of EI) of the authoring organisation which allows for the unique identification of the document across all practices.

The filler order number includes the site identifier of the organisation that generates the document/result/referral and the entitity entity identifier (generated by the clinical application) should which must be unique to each document/result/referral, within the same practicefiller site, over time. This should allow for corrected documents to be issued (using the same OBR-3 Filler Order number (EI) as the original document).

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Definition: This field is the identifier code for the requested observation/test/battery. This can be based on local and/or “universal” codes. We recommend the “universal” procedure identifier if available (eg e.g. SNOMED-CT). 

This field is used for the requested service. The RCPA Board approved Requesting Pathology Terminology Reference Set is available on the RCPA website. 

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In referral messages the referral summary is indicated by the OBR-4 code, which should be either a child concept of the SNOMED CT-AU concept 373942005 Discharge Summary (record artifact), for hospital discharge or a child of 3457005 | Patient referral (procedure) for provider to provider referral. This OBR/OBX group should contain the VMR data if available. Senders may include older referrals in a REF message but the current referral must appear as the first OBR/OBX group. A initial candidate set of record artifact decended descended codes has been submitted to the Australian Digital Health Agency 

4.4.1.4.1.1 Examples of codes (non-exhaustive) for use in referral messages to indicate referral summary.

Refer to SNOMED-CT AU for complete list of codes.

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Subcomponents of units: <identifier (ST)> & <test (ST)> & <name of coding system (IS)> & <alternate identifier (ST)> & <alternate text (ST)> & <name of alternate coding system (IS)>
Definition: For laboratory tests, the collection volume is the volume of a specimen. The default unit is ML. Specifically, units should be expressed using UCUM (unitsofmeasure.org). This is a results-only field except when the placer or a party has already drawn the specimen.

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Definition: When a specimen is required for the study, this field will identify the person, department, or facility that collected the specimen. Either name or ID code, or both, may be present.

In the Australian context, where possible, this XCN data must be populated using the method described in A10.1.2.1 XCN Datatype.

4.4.1.11 OBR-11 Specimen action code (ID) 00245

Definition: This field is the action to be taken with respect to the specimens that accompany or precede this order. The purpose of this field is to further qualify (when appropriate) the general action indicated by the order control code contained in the accompanying ORC segment. For example, when a new order (ORC - “NW”) is sent to the lab, this field would be used to tell the lab whether or not to collect the specimen (“L” or “O”).

HL7 Table 0065 - Specimen Action Code

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Snomed-CT AU is a recommended source terminology for this field. 

ege.g. 71837009^Cytotoxic agent (product)^SCT

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SNOMED-CT AU is recommended as a terminology source this field. e.g. 122575003&Urine Specimen&SCT

HL7 Table 0070 – Specimen source codes

The second component should include free text additives to the specimen such as Heparin, EDTA, or Oxlate, when applicable.

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The fourth component specifies the body site from which the specimen was obtained, and the fifth is the site modifier. For example, the site could be antecubital fossa, and the site modifier “right.” The components of the CE fields become subcomponents. Refer to HL7 Table 0163 – - Body site.  SNOMED-CT AU is recommended as a terminology source this field. e.g. 64033007&kidney structure&SCT

HL7 Table 0163 – Body site

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Definition: This field identifies the provider who ordered the test. Either the ID code or the name, or both, may be present. This is the same as ORC-12-Ordering provider. If ORC-12 does not contain the ordering provider then it must be present in the associated OBR and vice versa.  If the both, ORC-12 Ordering provider and OBR-16 Ordering Provider are valued, then both must contain the same value. When results are sent in an ORU message, an ORC is not required, so the identifying ordering provider must be present in the OBR segment.  See also PV1-8 Referring Doctor.

In the Australian setting Medicare provider numbers are used to provide a location specific identifier.

In the Australian context, where possible, this XCN data must be populated using the method described in A10.1.2.1 XCN Datatype.

In referral messages this field may be blank in the case of the referral letter, but the original value should be preserved in the case of existing reports that are being forwarded in OBR/OBX groups. e.g. copies of pathology and radiology reports.

4.4.1.17 OBR-17 Order callback phone number (XTN) 00250

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The ST field is encoded with repeating name=value pairs separated by commas. ege.g. |name=value,name=value,name=value|

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When transmitted all reserved HL7 delimiters must be escaped and the OBR-20 ST result extracted, unescaped and then parsed as a comma separated name=value pairs.

ege.g. |LN=2016-1234-XYZ\T\LBA| is extracted as LN=2016-1234-XYZ&LBA

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Definition: This field is the section of the diagnostic service where the observation was performed. If the study was performed by an outside service, the identification of that service should be recorded here.

Refer to HL7 Table 0074 - Diagnostic service section ID for for valid entries. This field is required in Australian implementations to indicate to the placer system which clinical area to display the results. 

HL7 Table 0074 - Diagnostic service section ID 

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Note: † An Australian extension to the the laboratory department code. 

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Definition: This field is the status of results for this order. This conditional field is required whenever the OBR is contained in a report or referral message. It is not required as part of an initial order.

There are two methods of sending status information. If the status is that of the entire order, use ORC-15- order effective date/time and ORC-5-order status. If the status pertains to the order detail segment, use OBR-25-result status and OBR-22-results report/status change - date/time. If both are present, the OBR values override the ORC values. This field would typically be used in a response to an order status query where the level of detail requested does not include the OBX segments. When the individual status of each result is necessary, OBX-11- observ result status may be used. In the Australian environment, when any part of a report is corrected,  a complete report, containing all the OBX segments should be transmitted with an OBR-25 status of 'C'. The individually updated OBX segments can be flagged with their own result status in OBX-11.

Refer to HL7 Table 0123 - Result status for valid OBR Result Status entries.

HL7 Table 0123 - Result status 

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Variance: While the International standard restricts this to 5 copy doctors, the Australian standard does not have this restriction and allows an unlimited number. 

In the Australian context, where possible, this XCN data must be populated using the method described in A10.1.2.1 XCN Datatype.

4.4.1.29 OBR-29 Parent (CM) 00261

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Definition: This field identifies how (or whether) to transport a patient, when applicable. Refer to HL7 Table 0124 - Transportation mode for valid codes.

HL7 Table 0124 - Transportation mode 

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Snomed-CT AU is a recommended source terminology for this field. 

ege.g. 274640006^Fever with chills (finding)^SCT

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Definition: This field identifies the physician or other clinician who interpreted the observation and is responsible for the report content. In the Australian context this field may be used for the billing doctor information.

This field should be valued where the original authoring provider for the content is known.

4.4.1.33 OBR-33 Assistant result interpreter (CM) 00265

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e.g. 161156004^Language difficulty (finding)^SCT161156004 | Lang161156004 | Language difficulty (finding)uage difficulty (finding)

4.4.1.40 OBR-40 Transport arrangement responsibility (CE) 01031

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Definition: This field is an indicator of whether transport arrangements are known to have been made.

Refer to HL7 Table 0224 - Transport arranged for valid codes.

HL7 Table 0224 - Transport arranged 

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Definition: This field is an indicator that the patient needs to be escorted to the diagnostic service department. Note: The nature of the escort requirements should be stated in the OBR-43-planned patient transport comment field. See 

HL7 Table 0225 - Escort required 

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Definition: This field contains a unique identifier assigned to the procedure, if any, associated with the Universal Service ID reported in field 4. User-defined Table 0088 - Procedure code is used as the HL7 identifier for the user-defined table of values for this field. This field is a CE data type for compatibility with clinical and ancillary systems. 

User-defined Table 0088 - Procedure code

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Definition: This field contains the procedure code modifier to the procedure code reported in field 44, when applicable. Procedure code modifiers are defined by regulatory agencies. Multiple modifiers may be reported. User-defined Table 0088 - Procedure code is used as the HL7 identifier for the user-defined table of values for this field.

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Definition: This field contains supplemental service information sent from the placer system to the filler system for the universal procedure code reported in OBR-4 Universal Service ID. This field will be used to provide ordering information detail that is not available in other, specific fields in the OBR segment. Multiple supplemental service information elements may be reported. Refer to User-defined table 0411 - Supplemental service information values for suggested values. This field can be used to describe details such as whether study is to be done on the right or left, for example where the study is of the arm and the order master file does not distinguish right from left or whether the study is to be done with or without contrast (when the order master file does not make such distinctions).

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User-defined Table 0411 - Supplemental service information values  

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Following the final atomic OBX segment are the OBX display segment(s) with the presented report. There must be at least one display segment per OBR segment and where there is more than one display type it must contain the same report detail. If there is a digital signature it will appear after the OBX display segments.

HL7 Attribute Table – OBX – Observation/Result

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All HL7 data types are valid, and are included in Table 0125 except CM, CQ, SI, and ID. For a CM definition to have meaning, the specifics about the CM must be included in the field definition. OBX-5- observation value is a general field definition that is influenced by the data type OBX-3, so CMs are undefined in this context. CQ is invalid because units for OBX-5-observation value are always specified explicitly in an OBX segment with OBX-6 units. SI is invalid because it only applied to HL7 message segments, and ID because it requires a constant field definition. The RP value (reference pointer) must be used if the actual observation value is not sent in OBX but exists somewhere else. For example, if the observation consists of an image (document or medical), the image itself may not necessarily be sent in OBX. The sending system may in that case opt to send a reference pointer. The receiving system can use this reference pointer whenever it needs access to the actual image through other interface standards, e.g., DICOM, or through appropriate servers.

HL7 Table 0125 - Value type 

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When local codes are used as the first identifier in this field we strongly encourage sending a universal identifier as well to permit receivers to equivalence results from different providers of the same service (e.g., a hospital lab and commercial lab that provides serum potassium to a nursing home). LOINC® is an HL7 approved code system for the Observation identifier. It covers observations and measurements, such as laboratory tests, physical findings, radiology studies, and claims attachments and can be obtained from loinc.org. LOINC codes, selected by the RCPA for Standards for Pathology Informatics in Australia (SPIA) reporting terminology reference sets which can be obtained at RCPA website or from the National Clinical Terminology Service.

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On occasions no code will be defined or available and only the text component of the CE will be valued.  Where a coded term exists in a standard terminology then the identifier and coding system name component should be valued.

There are specific LOINC codes used for result and report comments, template IDs and section headings detailed below in Section 4.6 (Specific LOINC codes) that modify the display of OBX segments and should be handled specifically.

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MSH|^~\&|EQUATORDXTRAY^EQUATORDXTRAY:3.1.2^L|Acme Pathology^1001^AUSNATA|||20160713174923+1000||ORU^R01^ORU_R01|07131749373-8576|P|2.4^AUS&&ISO3166_1^HL7AU.ONO.1&&HL7AU|||AL||AUS
PID|1|...
PV1|1|O||||||0626518F^DOCTOR^PAUL ^^^DR^^^AUSHICPR^L^^^UPIN|0626518F^DOCTOR^PAUL ^^^DR^^^AUSHICPR^L^^^UPIN|||||||N
ORC|RE||16-123456^Acme Pathology^1001^AUSNATA||CM|||||||0626518F^DOCTOR^PAUL ^^^DR^^^AUSHICPR^L^^^UPIN
OBR|1||16-123456^Acme Pathology^1001^AUSNATA|26604007^Full Blood Count^SNOMED-CT^CBC^^AUSNATA.15454||20160713+1000|20160713+1000|||||||||0626518F^DOCTOR^PAUL ^^^DR^^^AUSHICPR^L^^^UPIN||From Acme Pathology"XX07131747062-4944" 13.07.2016||LN=16-123456||201607131748+1000||PHYHM|F||^^^20160713+1000|0626518F^DOCTOR^PAUL ^^^DR^^^AUSHICPR^L^^^UPIN~0626518F^DOCTOR^PAUL^^^DR^^^AUSHICPR^L^^^UPIN||||0626518F&DOCTOR&PAUL &&&Dr.&&&AUSHICPR
OBX|1|RP|60572-5^^LN^ENTRY^^EN 13606|1|CEN.FULL-BLOOD-COUNT.v3^FULL BLOOD COUNT&99A-B758ABA873EFC4A1&L^TX^Octet-stream||||||F
OBX|2|NM|718-7^Haemoglobin^LN|1.1.1|118|g/L^g/L^UCUM|115-165||||F
OBX|3|NM|789-8^Red cell count^LN|1.1.2|3.9|10*12/L^10*12/L^UCUM|3.8-5.8||||F
OBX|4|NM|4544-3^Haematocrit^LN|1.1.3|0.39|L/L^L/L^UCUM|0.37-0.47||||F
OBX|5|NM|787-2^Mean cell volume^LN|1.1.4|88|fL^fL^UCUM|80-100||||F
OBX|6|NM|785-6^Mean cell haemoglobin^LN|1.1.5|28.0|pg^pg^UCUM|26.5-33.0||||F
OBX|7|NM|786-4^MCHC^LN|1.1.6|320|g/L^g/L^UCUM|310-360||||F
OBX|8|NM|777-3^Platelet count^LN|1.1.7|190|10*9/L^10*9/L^UCUM|150-400||||F
OBX|9|NM|6690-2^White cell count^LN|1.1.8|7.8|10*9/L^10*9/L^UCUM|4.0-11.0||||F
OBX|10|CE|70949-3^^LN|1.1.9|DIFF^Differential^L||||||F
OBX|11|NM|26499-4^Neutrophils^LN|1.1.9.1|4.0|10*9/L^10*9/L^UCUM|2.0-7.5||||F
OBX|12|NM|26474-7^Lymphocytes^LN|1.1.9.2|3.2|10*9/L^10*9/L^UCUM|1.0-4.0||||F
OBX|13|NM|26484-6^Monocytes^LN|1.1.9.3|0.4|10*9/L^10*9/L^UCUM|0.2-1.0||||F
OBX|14|NM|26449-9^Eosinophils^LN|1.1.9.4|0.2|10*9/L^10*9/L^UCUM|0-0.4||||F
OBX|15|NM|26444-0^Basophils^LN|1.1.9.5|0.0|10*9/L^10*9/L^UCUM|0-0.1||||F

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Definition: This field contains a table lookup indicating the normalcy status of the result. We strongly recommend sending this value when applicable. (See ASTM 1238 - review for more details). Refer to User-defined Table 0078 - Abnormal flags for valid entries.

When the laboratory can discern the normal status of a textual report, such as chest X-ray reports or microbiologic culture, these should be reported as N when normal and A when abnormal. Multiple codes, e.g., abnormal and worse, would be separated by a repeat delimiter, e.g., A~W.

User-defined Table 0078 - Abnormal flags 

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Definition: This field contains the nature of the abnormal test. Refer to HL7 Table 0080 - Nature of abnormal testing for valid values. As many of the codes as apply may be included, separated by repeat delimiters. For example, normal values based on age, sex, and race would be codes as A~S~R.

HL7 Table 0080 - Nature of abnormal testing 

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Definition: This field contains the observation result status.

Refer to HL7 table 0085 - Observation result status codes interpretation for valid values.

This field reflects the current completion status of the results for one Observation Identifier. It is a required field. Previous versions of HL7 stated this implicitly by defining a default value of “F.” Code F indicates that the result has been verified to be correct and final. Code W indicates that the result has been verified to be wrong (incorrect); a replacement (corrected) result may be transmitted later. Code C indicates that data contained in the OBX-5-observation value field are to replace previously transmitted (verified and) final result data with the same observation ID (including suffix, if applicable) and observation sub-ID usually because the previous results were wrong. Code D indicates that data previously transmitted in a result segment with the same observation ID (including suffix) and observation sub-ID should be deleted.

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Multiple preliminary results may be reported at different observation times. e.g. a microbiology culture.

HL7 Table 0085 - Observation result status codes interpretation 

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Definition: When required, this field contains the identifier of the individual directly responsible for the observation (i.e., the person who either performed or verified it). In a nursing service, the observer is usually the professional who performed the observation (e.g., took the blood pressure). In a laboratory, the observer is the technician who performed or verified the analysis. The code for the observer is recorded as a CE data type. If the code is sent as a local code, it should be unique and unambiguous when combined with OBX-15-producer ID.

In the Australian context, where possible, this XCN data must be populated using the method described in A10.1.2.1 XCN Datatype.

4.4.2.17 OBX-17 Observation method (CE) 00936

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When an OBX segment contains Free Text (FT) data the value of OBX-3 Observation Identifier is not displayed to the user and the text is displayed across the full width of the users display window to allow for a minimum of 80 columns of text to be displayed. If fillers wish a heading to be displayed in association with FT OBX segments the heading text should be included within OBX-5 as part of the FT data. Systems displaying results should ensure that there is a minimum of 80 columns of displayable text and should also use a non proportional font to allow fillers to reliably format the text. Fillers have no control over the font used for display, but can assume that it is non proportional and there is sufficient room for 80 columns of character data to display without word wrapping.

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Australia uses an extension to the HL7 conventions by including at least one, but potentially many OBX segments that contain a display orientated version of the data included in the message. Ideally the data should be transmitted in atomic form as well as a display orientated form, but in some cases only the display orientated data is transmitted. (In which case the display segment will be the only OBX segment present) These OBX segments are positioned as the last OBX segments and can be identified by the use of the coding scheme "AUSPDI" in OBX-3 Observation Identifier, Name of Coding System. There are multiple potential formats that the display orientated version of the data can be transmitted but all display segments should be equivalent and contain a rendering of all the data and (if atomic data is present) should not contain clinical results not included in the atomic data. For each display format there must be only one 'AUSPDI' OBX segment. The potential formats are given in the following table.

See conformance points section HL7au:000008.

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For receivers, when a display segment is shown, earlier atomic OBX segments should not be rendered (See HL7au:000008.1.6). Where there is one or more display segments available only one should be visible at a time, however the system must allow users to access the alternative formats provided. See HL7au:000008.1.1.

4.5.1 Using the PIT display format

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4.5.3 Using the HTML display Format

The html HTML format uses xhtml XHTML and the details regarding the format of the html are given in the Appendix. xHTML XHTML display data should be base64 encoded in an ED segment. The xhtml XHTML should be valid xml. Any html HTML display segment SHOULD be displayed with a compliant browser control. These are available of virtually all platforms an ensure reliable display of compliant xhtmlXHTML. When handled correctly xhtml XHTML is the most inter-operable of all formats.

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OBX|6|ED|PDF^Display in PDF Format^AUSPDI||MERIDIAN&MERIDIAN:3.1.2 [win32-i386]&L^AP^PDF^Base64^JVBERi0xLjML^application^pdf^Base64^JVBERi0xLjM...OQ0KJSVFT0YNCg==||||||F

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This mechanism uses the display abilities of HL7 Free Text to produce a rendering of the whole report. The only text formatting available is highlighting which is usually implemented in receiving systems as bold. Text display segments use a value type of FT and the usual escaping of delimiters and Free Text formatting commands.

4.6 Specific LOINC codes

4.6.1 Result Comments

NTE segments are not used in the Australian setting but comments about individual results (A single OBX) or a report (All OBX segments under a OBR Segment) are supported by the use of OBX segments with specific LOINC codes. Result Comments are in an OBX segment immediately following the result OBX and report comments are contained in an OBX segment at the end of the report but before the display orientated OBX segments detailed in Section 4.5. The LOINC code in a Comment OBX Segment (In OBX-3) allows differentiation between result and report comments. Ideally result comments should be linked to result by use of OBX-4 Observation Sub-ID as well as the position in the message.

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The value of OBX-3 "Generated Comment" SHOULD NOT be displayed as per FT display conventions.

4.6.2 Section Headings

In structured reports there may be a number of sections in a report and these OBX segments are defined by 2 specific LOINC codes

When these codes are used the display of OBX-3 should be suppressed and the Value component displayed as a heading. The value component is usually of type CE (Coded Entry) or ST (String). These LOINC codes are usually used in conjunction with the OBX-4 Observation SubID to allow repetition of the codes for multiple headings and nested sections.

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OBX|2|CE|70949-3^^LN^CLUSTER^^EN 13606|1.1|70949-3^Clinical details^LN||||||F

4.6.3 Template Identifiers

When highly structured reports are used to report complex results such as Colorectal Cancer Histopathology the reports as based on a template. The template is identified by:

This OBX segment can be omitted from the display but for systems capable of interpreting the template provides an identifier for the template that the data confirms to. Any data in the list of OBX segments under the current OBR segment that has a OBX-4 Observation SubID starting with the SubID of the Template identifier OBX is a part of the templated data.

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OBX-8 Abnormal flags should be taken into consideration and atomic results with abnormal flags SHOULD be highlighted, generally by coloring the data red to highlight the fact that the result is abnormal or out of the reference range. If colour is used, then highlighting must be achieved by an additional method not relying on colour to accommodate colour blind readers. The abnormal flags SHOULD be displayed and displayed immediately after any Numeric, Structured numeric, String or Coded data.

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The display of Free Text (FT) data SHOULD use a non proportional font to allow data of separate lines to align. This display SHOULD allow for a minimum of 80 characters before any word wrapping occurs. Free Text that is specified as able to be wordwrapped should word wrapped should be word wrapped to make it visible to the user on one screen and not be hidden off the right hand side of the screen as one line of text.

...

4.9 Pathology terminology

Pathology terminology is published on the RCPA website and the National Clinical Terminology Service.

...

• Units of measure should always be shown where a quantity is shown on pathology reports.
• The exception is where it is explicit that no units are used for a particular test such as Human chorionic gonadotropin qual.
• Pathology reports should use the units specified in the Standards for Pathology Informatics in Australia (SPIA) for those tests where units have been determined.
• A single, standardised unit of measure should be used for tests in reports from pathology laboratories.
• There may, however, be valid exceptions to this rule; 
  • • in a transition from one preferred unit to another 
    • where alternate units are required by legislation or regulation such as for a registry 
    • during a period of consensus building as to which will be the preferred unit, but this period should be as short as practical 
    • where a facsimile of an historic report is produced – historic data need not comply.
• Units should be represented in electronic messages in fields for units in such a way that receiving systems can readily convert units under the clinical governance of the receivers. The Unified Code for Units of Measure (UCUM) must be used where it is the intention to represent units in a computable form (see http://unitsofmeasure.org/).
• Where the unit is not specified here, UCUM should be used for the unit. UCUM lexical elements such as square brackets (‘[’ and ‘]’) can be removed in the display format for enhanced clarity. However, the fully defined UCUM syntax should be used in electronic messaging.
• Superscripts and subscripts should not be used in units.
• The caret symbol (^) should be used to represent “raised to a power of”. Care must be taken to appropriately “escape” and "unescape" the caret symbol (^) as this symbol is used as a component separator in HL7 messages. Refer to examples in clause G6.08. 
• Units raised to a power should be indicated in the preferred display unit by the exponent as an integer written immediately behind the unit term. For example, the preferred display unit for millilitre per minute per 1.73 square metre is mL/min/1.73m^2. Powers of ten should be represented by 10^ e.g. 10^12/.
  • • Display example:  
      • mL/min/1.73m^2  
      • 6.1x10^12/L  
    • Message example:  
      • ml/min/1.73m\S\2 
      • 6.1x10\S\12/L

4.11 SPIA Rendering of numeric results, ranges, units, previous results and flagging

The following is a summary of chapter 7 Rendering of numeric results, ranges, units, previous results and flagging from the RCPA's Standards for Pathology Informatics in Australia (SPIA), for further detail refer to this document.

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3. Numeric results are incomplete without associated units and guidance for interpretation (eg e.g. reference intervals) and so these must always be shown with the number.

...

• Numeric results must be right justified (when shown in columns) and have corresponding guidance values (e.g. reference interval) and units if these exist.
• Numeric results must have a leading zero where there is no number in the units place (i.e. 0.7 not .7).
• For columnar cumulative reports the latest result must be shown in the furthest right column of results (i.e. time must go from left to right across the page) or at the top for cumulative reports shown in rows (i.e. time must go from the bottom to the top of the page).
• The latest result must be differentiated from earlier results by at least two methods one of which is a heading ‘Latest Results’.
  • A box such as that shown in Figure 3 was favoured by 75% of survey respondents for columnar reports.
  • Bolding of the heading text was considered effective by the Committee.
• Guidance values must be bounded by parentheses and have no spaces.
• Italics should not be used.
• The column showing units must be headed ‘Units’, be left justified and be to the immediate right of the ‘Reference’ column.
• The numbers used for guidance must be rendered with the same number of decimal places as the related result.
• For some analytes, such as tumour markers, a result may be orders of magnitude above guidance in which case current practice for some laboratories is to adjust for significant figures because of concern at overstating precision. It is not known whether it is safer to do this or to adopt the number of decimal places for the low range result. If a different number of decimal places is used at different concentrations, the guidance should be rendered to the same number of decimal places as the results of a similar magnitude to the guidance values.
• Results are considered outside the guidance values if after rounding to the format of the displayed result (and the guidance) the result is greater than the higher number or less than the lower number of the guidance values. S7.10  Results outside the guidance values must be highlighted by at least two methods one of which is either an ‘L’ or ‘H’ one space to the right of the result (‘L’ for a result lower and ‘H’ for a result higher).
• A single asterisk (‘*’) and the ‘+’ and ‘-‘characters should not be used for flagging results
• Underlining of results should not be used for highlighting results
• Colour was preferred by most respondents in the survey but because of colour blindness and possible loss of colour in some communications, if colour is used, then the font should also be bolded.
• Multi-level flagging may be used in which case ‘LL’ or ‘HH' should be used for the second level.
• Headings must be differentiated from test names.
• Dates must be shown in the form 30-Jan-14 (i.e. not in the form 30/01/14).

4.12 Harmonised reference intervals

The following is a summary of chapter 8 Harmonised reference intervals from the RCPA's Standards for Pathology Informatics in Australia (SPIA) for further detail refer to this document.

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More recently in the RCPA PITUS 15-16 working group 5 "Report modelling for safe atomic reporting to registries" have progressed FHIR artefacts which are then transported in a HL7 V2.4 message. The initial work is based on the colorectal cancer protocol and the prostate (radical prostatectomy) cancer protocol and is available at http://fhir.hl7.org.au/fhir/rcpa/index.html.

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In the OBX segments, the same LOINC code is used to indicate the item eg e.g. unit of blood or fresh frozen plasma etc, and OBX-4 Observation sub-ID is used to indicate the separate units of red cells or fresh frozen plasma etc.

...

MSH|^~\&|EQUATORDXTRAY^EQUATORDXTRAY^L|Acme Pathology^1001^AUSNATA|||20150420221113+1000||ORU^R01^ORU_R01|20150420.123321|P|2.4^AUS&&ISO3166_1^HL7AU.ONO.1&&HL7AU|||AL||AUS
PID|1|...
PV1|1|O||||||01234567W^BROWN^Bill^^^DR^^^AUSHICPR^L^^^UPIN|01234567W^BROWN^Bill^^^DR^^^AUSHICPR^L^^^UPIN
ORC|RE||03-7654321-URC-0^Acme Pathology^1001^AUSNATA||CM|||||||01234567W^BROWN^Bill^^^DR^^^AUSHICPR^L^^^UPIN
OBR|1||03-7654321-URC-0^Acme Pathology^1001^AUSNATA|URC^URINE MICRO^L|||201503081300+1000|||||||201503081928+1000||01234567W^BROWN^Bill^^^DR^^^AUSHICPR^L^^^UPIN||||DR=MME,LN=03-7654323,RC=Y||201504181642+1000||MB|F||^^^201503080000+1000|01234564W^GREEN^Wilma^^^DR^^^AUSHICPR^L^^^UPIN||||Reporting Pathologist
OBX|1|ST|19159-3^Collection Method^LN||Mid stream urine||||||F|||201503082316+1000
OBX|2|ST|25428-4^Glucose^LN||Negative||||||F|||201503082350+1000
OBX|3|ST|2514-8^Ketones^LN||Negative||||||F|||201503082350+1000
OBX|4|ST|20454-5^Protein^LN||+||||||F|||201503082350+1000
OBX|5|NM|30405-5^Leucocytes^LN||40|10*6/L^10*6/L^UCUM|<10|+|||F|||201503090015+1000
OBX|6|NM|30391-7^Erythrocytes^LN||20|10*6/L^10*6/L^UCUM|<10|+|||F|||201503090015+1000
OBX|7|SN|30383-4^Epithelial cells^LN||<^10|10*6/L^10*6/L^UCUM|||||F|||201503090015+1000
OBX|8|ST|8269-3^^LN|1|Organism 1||||||F
OBX|9|CE|630-4^Bacteria Identified^LN|1|40886007^Klebsiella oxytoca^SCT|||A|||F
OBX|10|SN|19090-0^Colony Count^LN|1|>^10|||A|||F
OBX|11|ST|18864-9^Amp/Amoxycillin^LN|1|R|||R|||F
OBX|12|ST|18862-3^Amoxycillin+Clavulanic acid^LN|1|R|||R|||F
OBX|13|ST|18897-9^Cephalexin^LN|1|R|||R|||F
OBX|14|ST|18955-5^Nitrofurantoin^LN|1|R|||R|||F
OBX|15|ST|18956-3^Norfloxacin^LN|1|S|||S|||F
OBX|16|ST|18997-7^Trimethoprim^LN|1|R|||R|||F
OBX|17|ST|18928-2^Gentamicin^LN|1|S|||S|||F
OBX|18|ST|8270-1^^LN|2|Organism 2||||||F
OBX|19|CE|630-4^Bacteria Identified^LN|2|73457008^Protues mirabilis^SCT|||A|||F
OBX|20|SN|19090-0^Colony Count^LN|2|>^100|||A|||F
OBX|21|ST|18864-9^Amp/Amoxycillin^LN|2|R|||R|||F
OBX|22|ST|18862-3^Amoxycillin+Clavulanic acid^LN|2|S|||S|||F
OBX|23|ST|18897-9^Cephalexin^LN|2|S|||S|||F
OBX|24|ST|18955-5^Nitrofurantoin^LN|2|S|||S|||F
OBX|25|ST|18956-3^Norfloxacin^LN|2|S|||S|||F
OBX|26|ST|18997-7^Trimethoprim^LN|2|R|||R|||F
OBX|27|ST|18928-2^Gentamicin^LN|2|S|||S|||F
OBX|28|FT|8251-1^Generated comment^LN||\.br\May be suggestive of UTI in the presence of symptoms.\.br\||||||F

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https://labtest.com.au/mylabapp/data%20path/id/2016F0001000-1?viewview=jpegrender&mode=online

We will match the URL parts as follows:

These parts would be encoded into a RP datatype as follows:

...

...

The pathology provider will respond with the the following ORR^O02 message - ignoring the two-stage acknowledgement for this scenario: 

...

In this scenario the test resulted is the same the the test ordered; hence there no combining or replacing of test codes as per scenario 1 and 2.

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A pathology provider will want to match the patient identifier to enable the provision of cumulative results which provides more information over time than just a snapshot and Medicare has rules on some tests regarding the frequency a test can be ordered over a period of a specific period of time.  The pathology results receiver will want the patient identifier to match results on a patient where the order originated from another provider eg e.g. copy to doctor, to determine if it is an existing patient or a new patient to their patient management system. It is therefore useful to the receivers of the request or the results to receive as many patient identifiers as possible.

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4.23 Tracking Result Identifiers

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When an electronic request is made the order will be transmitted to the laboratory, the laboratory must respond with with a Filler Order Number: If the order contains more than one order on the same request ie i.e. same Placer Group Number then the laboratory must respond with the same number of order responses. 
The preferred response is to respond immediately to the order with an ACK message and transmit an ORR message with a Filler Order Number when the specimen is received.
An optional method is for the laboratory to hold the order and not respond until the specimen has been received by the laboratory and the lab number can be used as one part of the Filler Order Number. 

...

MSH|...
PID|...
PV1|....
ORC|RE||11P123456-98765432^MLS^2623^AUSNATA|996042222^SNP^1964^AUSNATA|CA||||20160623164200|JAMB^James Brown^^^^^^^NATA2623||049266KX^Teste^Testy^^^Mr^^^AUSHIC|||20160810171724
OBR|1||11P123456-98765432^MLS^2623^AUSNATA|ALL^ALL^NATA2623||20110623164200|20160623164200|||||""|Nil - Testing Hl7|||049266KX^Teste^Testy||MPATH|KEST|IMAGE|12552953|||CH|X
OBX|1|ST|ALL^ALL^L|1|Delete all results for this report||||||D

Anchor
4.26 4.26

4.26 Non-Displayable Supporting data

Encapsulated data attachments are non-displayable files that are ancillary to the main report. They are not e.g. images that form part of the report, related documents, or data which could be used in a display segment. An example of an attachment would be raw XML data from an instrument. Documents which are related to the current report (defined by the OBR) and are displayable using one of the supported AUSPDI display segment datatypes should appear under their own OBR. Attachments can also be represented inline (meaning under the same OBR) or under their own OBR which has the advantage of having a unique document identifier for citation purposes (OBR-3 Filler Order Number), a representation of relevant dates and authorship to be associated with the attachment. Where an attachment is used some narriative documenting the attachment should appear in the display segment associated with the OBR under which the attachment appears.

...

...

ORC|RE||2.25.263498878813690208021966154988434320272^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO||CM|||||||0191324T^MCINTYRE^ANDREW^^^^^^AUSHICPR^L^^^UPIN
OBR|1||2.25.263498878813690208021966154988434320272^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO|18842-5^Discharge Summarization Note^LNote^LN|||20140825103830|||||||||2671351T^Doctor^Good^^^Dr^^^AUSHICPR||||||20140825103830||PHY|F||^^^20140825103830
OBX|1|ED|18842-5^Discharge Summarization Note^LN||^application^x-hl7-cda-xdm-zip^base64^UEsDBBQ
OBX|2|ED|HTML^Display format in HTML^AUSPDI||^text^html^Base64^PD94bWwgdmVyc2lvbj0iMS4wIj8+Cjwh....
OBX|3|ED|PDF^Display in PDF Format^AUSPDI||^application^pdf^Base64^JVBERi0xLjQNCiXi48/TDQolDQol...ORC|RE||12123-1^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO||CM|||||||0191324T^MCINTYRE^ANDREW^^^^^^AUSHICPR^L^^^UPIN

ORC|RE||12123-2^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO||CM|||||||0191324T^MCINTYRE^ANDREW^^^^^^AUSHICPR^L^^^UPIN
OBR|3||12123-2^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO|52033-8^General correspondence^LN Note^LNote^LN|||20140825103830|||||||||2671351T^Doctor^Good^^^Dr^^^AUSHICPR||||||20140825103830||PHY|F||^^^20140825103830
OBX|1|ED|52033-8^General correspondence^LN|2|^application^octet-stream^Base64^...||||||F
OBX|2|ED|PDF^Display format in PDF^AUSPDI||^application^pdf^Base64^...||||||F|||20170322

ORC|RE||12123-3^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO||CM|||||||0191324T^MCINTYRE^ANDREW^^^^^^AUSHICPR^L^^^UPIN
OBR|4||12123-3^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO|52033-8^General correspondence^LN Note^LNote^LN|||20140825103830|||||||||2671351T^Doctor^Good^^^Dr^^^AUSHICPR||||||20140825103830||PHY|F||^^^20140825103830
OBX|1|ED|PDF^Display format in PDF^AUSPDI|Supporting Letter|^application^pdf^Base64^...||||||F|||20170322
OBX|1|ED|RTF^Display format in RTF^AUSPDI|Supporting Letter|^application^rtf^Base64^...||||||F

ORC|RE||12123-4^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO||CM|||||||0191324T^MCINTYRE^ANDREW^^^^^^AUSHICPR^L^^^UPIN
OBR|5||12123-4^Good Hospital^1.2.36.1.2001.1003.0.8003629900024197^ISO|52070-0^Workers compensation^LN|||20140825103830|||||||||2671351T^Doctor^Good^^^Dr^^^AUSHICPR||||||20140825103830||PHY|F||^^^20140825103830
OBX|1|ED|PDF^Display format in PDF^AUSPDI|claimform1|^application^pdf^Base64^...||||||F|||20170322

...

To refer to another document under another OBR then the OBR can be referenced using an OBX EI (Entity Identifier) with a OBX-3 Observation Identifier value of LP72255-0^Citation^LN.

ege.g. 

OBX|4|EI|LP72255-0^Citation^LN||1234^ACME Pathology^7654^AUSNATA||||||F

...