Page Comparison

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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 laboratory system, Radiology system) (the filler), to the ordering syste4.4.1.25 OBR-25 Result status (ID) 00258m (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.

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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 

Legend:

** ALERT: The field length of OBR-2 and OBR-3 of 250 characters for Australian usage is a variance to the HL7 V 2.4 field length of 22 characters.
*** ALERT: The field length of OBR-9 of 250 characters for Australian usage is a variance to the HL7 V 2.4 field length of 20 characters.

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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: 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

4.4.1.12 OBR-12 Danger code (CE) 00246

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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

The fifth component indicates whether the specimen is frozen as part of the collection method. Suggested values are F (Frozen); R (Refrigerated). If the component is blank, the specimen is assumed to be at room temperature.

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The current allowable codes are:

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.

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Refer to HL7 Table 0074 - Diagnostic service section ID 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 

4.4.2 OBX - Observation/Result segment

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

HL7 Table 0123 - Result status 

4.4.1.26 OBR-26 Parent result (CM) 00259

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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 

4.4.1.31 OBR-31 Reason for study (CE) 00263

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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 

4.4.1.42 OBR-42 Escort required (ID) 01033

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 

4.4.1.43 OBR-43 Planned patient transport comment (CE) 01034

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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

4.4.1.45 OBR-45 Procedure code modifier (CE) 01316

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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  

Individual implementations may extend this table using other appropriate vocabularies.

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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

** ALERT: The field length of OBX-2 of three characters for Australian usage is a variance to the HL7 V 2.4 field length of two characters.

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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 

Strikethrough Elements should not be used in Australian implementations. FT should be used instead of TX. The extended version of datatypes should be used rather than datatypes from prior versions of HL7 V2.

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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 www.regenstrief.org/loinc/loinc.htm. 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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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 

4.4.2.9 OBX-9 Probability (NM) 00577

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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 

4.4.2.11 OBX-11 Observation result status (ID) 00579

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.

When changing or deleting a result, multiple OBX segments with the same observation ID and observation sub-ID are replaced or deleted as a unit. Normal progression of results through intermediate (e.g., ‘gram positive cocci’) to final (e.g., ‘staphylococcus aureus’) should not be transmitted as C (correction); they should be transmitted as P or S (depending upon the specific case) until they are final.

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

HL7 Table 0085 - Observation result status codes interpretation 

4.4.2.12 OBX-12 Date last observation normal value (TS) 00580

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See conformance points section HL7au:000008.

Display Format codes

• Only the Code and Coding System are significant and the text may be absent or vary from what is shown.
• *PIT display is deprecated and will be removed in future standards. Note that references to PIT are left in with "strikethrough" styling here to alert readers to its existence and that it is currently used in practice although not recommended for use by senders, receivers may find that they need to support it for practical reasons.

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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.

Most Comment OBX segments are of type FT and no display of the code or text in OBX-3 is expected but comment OBX segments can be of other value types and OBX-3 should not be displayed in those cases either.

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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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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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4.9 Pathology terminology

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

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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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We will match the URL parts as follows:

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

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https://images.rad.com.au/imageserver?Parameter1&Parameter2=Value2

This then would be encoded into an OBX as follows:

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Hence, the use of the correlation between the placer order number and the requested test provides the most suitable way of determining if an order has been completed. This process does not rely on matching order codes with result codes which are quite often different.

4.17.2 Reconciling Results

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Comments can be associated with results and more generally with the report.  To indicate which is being referenced the following protocol is used:

4.21 Processing FT value types in OBX segments

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In the Australian context the following elements are defined for OBR-20.

4.23 Tracking Result Identifiers

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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^L|||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^L|||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^L|||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

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