1 Introduction

Australian Diagnostics and Referral Messaging - Localisation of HL7 Version 2.4, Release 2 is the Australian localisation of the international HL7 V2 Standard covering the Laboratory/Diagnostics/Clinical result reporting, laboratory/radiology ordering specification and patient referral. The term "Diagnostics" covers non laboratory reporting including reporting of diagnostic imaging and non referral related clinical reporting (for example: echocardiography, respiratory function, endoscopy, stress testing, sleep studies). The term pathology in Australia covers all aspects of laboratory medicine including clinical and anatomical pathology domains, while the term “radiology” is understood to include all diagnostic imaging modalities, whether X-ray based or other (e.g. ultrasound). 

The relationship between pathology and radiology practices and their customers in Australia is considered by Government and others as similar to that between other consultant specialists and their customers. For that reason, what HL7 would call an order is generally called a request here and the response by the pathology provider (a formal term meaning the responsible specialist(s)) is called a report.  For some disciplines such as microbiology, anatomical pathology, genetics and genomics the request is more by way of asking a clinical question expecting the pathology provider to understand the best way of answering it - e.g. Is this cancer, if so what type, and what is the prognosis? It is expected this form of requesting will become more common as laboratory medicine evolves. In radiology, it is generally necessary for the request to include clinical information relevant to the purpose of the request, to enable the optimal choice, and interpretation, of the examination.  It is also frequently necessary that the request contain information relevant to safety issues that may arise from performance of the test, such as contrast allergies, renal disease, etc.

The use case here focuses on widely-available, well-standardized methods that will support the secure access to electronic laboratory and radiological requests and results and interpretations for clinical care by authorized parties and is driven by the need for timely electronic access to requested, referred and historical lab results. Requesting clinicians (the Placer) receive test results in the form of a HL7 V2 message, as a response to a request (electronic or paper) or as an unsolicited message by having the report directly sent by the pathology practice (the Filler) to the clinician for importation into their local systems. Images generated in the course of a radiological procedure are not sent in an HL7 message. Depending on the referrer’s requirements, and local technical capabilities, images may be made available on traditional analogue film (rapidly becoming obsolete), portable digital media, or, increasingly, in digital form via an online electronic portal.

Referral messaging covers clinical referral between clinicians and hospitals, as well as hospital discharge and includes a patient history summary suitable for constructing a Virtual Medical Record for use in decision support and can include any pathology/radiology/diagnostics reports relevant to the referral. It also includes a Medication summary. 

This document tries to provide coverage for all laboratory and radiological messaging scenarios in the Australian context including public and private entities, hospital and community and public health entities. The referral messaging covers referral between medical practitioners, allied health and hospitals. It covers referral between practitioners, referral to hospitals and hospital discharge.

The Royal College of Pathologists of Australasia (RCPA) has developed a number of policies around safety in requesting and reporting of pathology including the use of terminology and the transmission of data.  These policies have been incorporated into this document. Similarly, the Royal Australian and New Zealand College of Radiologists has defined minimum requirements for the content of referrals and reports.  Standardised terminology for radiological procedures is being developed, and will be progressively implemented throughout the sector.

This document and the specifications in it supersede those in AS 4700.2-2012 - Implementation of Health Level Seven (HL7) Version 2.4 - Pathology and diagnostic imaging (diagnostics) and HB 262 (Rev)-2012 - Guidelines for messaging between diagnostic providers and health service providers, and AS 4700.6-2006 Implementation of Health Level Seven (HL7) Version 2.4 Part 6: Referral, discharge and health record messaging.

1.1 Purpose

This guide contains the necessary specifications for pathology and radiology requests and reports in Australian healthcare using the HL7 V2.4 protocol. Where appropriate aspects of later versions of HL7 V2 have been incorporated into this localization. Where this is done it is flagged as a variation from v2.4.

1.2 Audience

This guide is designed for use by analysts and developers who require guidance on optional and ambiguous elements of an Australian constrained HL7 Version 2.4.  Users of this guide must be familiar with the details of HL7 message construction and processing.  This guide is not intended to be a tutorial on that subject.

1.3 Scope

This specification covers the exchange of laboratory results or clinical referral from an appropriate requesting provider or organisation to the testing/consulting source and the transmission of the result from the testing source or clinician to the recipient.  One of the primary features of this implementation guide is its focus on key points of broad interoperability.  These key points include the following:

• Use of strong identifiers for key information objects – These information objects include patients, orders, providers and organizations.  A strong identifier is one that uniquely identifies the object in question in a global fashion.  This means the identifier includes enough information to remain unique when taken out of the context within which the identifier was created.  For patients, providers and organisations this is achieved through the use of the use of the Individual Healthcare Identifier (IHI), Healthcare Provider Identifier–Individual (HPI–I) and Healthcare Provider Identifier–Organisation (HPI–O). In places Medicare Provider numbers are used to provide for location specific provider identifiers. Healthcare Provider Identifier-Organisation (HPI-O) identifiers are not currently available for all organisations at the required level of granularity and alternative organisation identifiers are usually used.

• Use of Vocabulary Standards ­ This guide calls for specific vocabulary standards for the exchange of laboratory information.  Use of standard vocabularies is important for a number of reasons.  Use of standard vocabularies allows broad distribution of healthcare information without the need for individual institutions to exchange master files for data such as test codes, result codes, etc.  Each institution ideally uses the standard codes or maps its own local vocabularies to the standard code, allowing information to be shared broadly, rather than remaining isolated as a single island of information.  Standard vocabularies, particularly coded laboratory results, enable more automated decision support for patient healthcare, as well as more automated public health surveillance of populations.

• Use of consistent specifications across Laboratory/Radiology/Clinical usage. The specification of segment usage and display rules is common to all message types allowing documents to be carried in multiple message types (ORU^R02 or REF^I12) and displayed/processed using common logic in receiving software. This permits the packaging of reports (laboratory/radiology/clinical) for the purpose of  referral messaging with no loss of atomic data, identifiers or terminology, preserving the potential for decision support and allows consistent result filing and display by the receiver.

1.4 Conventions

This guide adheres to the following conventions:

• The guide is constructed assuming the implementer has access to the 2.4 version of the HL7 Standard.  Although some information from the standard is included in this implementation guide, much information from the standard has not been repeated here.

• Data types have been described separately from the fields that use the data types. 

• No conformance information is provided for optional message elements.  This includes length, usage, cardinality, value sets and descriptive information.  Implementers' who want to use optional message elements should refer to the HL7 Standard to determine how these optional message elements will be used. Use of optional message elements should not change the interpretation of data sent using the standard elements.

The following table describes the various attributes used by this guide to document data type attribute tables, message structure attribute tables and segment attribute tables.  Not all attributes apply to all attribute tables.