V2 Messages

HL7's Version 2.x messaging standard is the workhorse of electronic data exchange in the clinical domain and arguably the most widely implemented standard for healthcare in the world. There have been seven releases of the Version 2.x Standard to date.

The HL7 Standard covers messages that exchange information in the general areas of:

• Patient Demographics
• Patient Charges and Accounting
• Patient Insurance and Guarantor
• Clinical Observations
• Encounters including Registration, Admission, Discharge and Transfer
• Orders for Clinical Service (Tests, Procedures, Pharmacy, Dietary and Supplies)
• Observation Reporting including Test Results
• The synchronization of Master Files between systems
• Medical Records Document Management
• Scheduling of Patient Appointments and Resources
• Patient Referrals—Specifically messages for primary care referral
• Patient Care and problem-oriented records.

Version 2.7 is currently being balloted at the normative level. Due to its widespread use, Version 2 will, no doubt, continue to play an integral part in healthcare messaging, even with the HL7 Version 3 Normative Edition. HL7 is committed to supporting and extending Version 2 in parallel with Version 3, providing continuity for current installations.

HL7 Version 2.6 represents HL7's latest development efforts to the line of Version 2 Standards that date back to 1989. Version 2.6 represents a major revision to Versions 2.5 and 2.5.1, refining and updating existing messages and adding new messages and domains all based upon proposals submitted and accepted by the HL7 membership.

Global changes include the following:

1. the addition of a new segment, UAC – User Authentication Credential, to ALL messages
2. the replacement of the TS – Timestamp data type with the DTM – Date/Time data type
3. the replacement of the CE – Coded Element data type with either the CNE – Coded with No Exceptions data type or the CWE – Coded with Exceptions data type
4. the deprecation of the CNN, NDL, LA1 and LA2 data types
5. the inclusion of "external" tables referencing a set of coded values defined and published by another standards organization assigned an HL7 number but without designation as an HL7 table (as was previously the practice)
6. the revision of examples in all chapters to support HIPAA compliance
7. the inclusion of a new chapter supporting electronic messaging transactions of claims and reimbursement data (which is produced for implementations of HL7 outside of the United States; in the United States, HIPAA law mandates an already in-use set of implementation guides of X12 messages for these purposes)
8. the inclusion of a new chapter supporting electronic messaging transactions of supply chain management data within healthcare facilities

HL7 Version 2.5.1 — this extension of Version 2.5 was due to a recent interpretation of the requirements of the Clinical Laboratory Improvements Amendment (CLIA) of 1988 related to the exchange of electronic laboratory information between clinical laboratories operating in California, USA, and external agencies; these Version 2.5.1 revisions have been carried forward into Version 2.6. HL7 was informed of a need to include a limited number of additional fields to the OBX Segment defined in Version 2.5 to support compliance. Although we have not been able to confirm requirements throughout the European Union, the addition of these elements to the OBX may also facilitate meeting the laboratory reporting requirements stipulated by the United Kingdom Accreditation Service [UKAS] and Clinical Pathology Accreditation (UK), Ltd [CPA]. These revisions were confined to chapters 2, 4, 7 and 9 of HL7 Version 2.5.1.

Released in 2003, Version 2.5 incorporated a number of new events, segments and messages, as well as a significantly expanded chapter on Control. Version 2.5 had more consistency and supported more functionality than any of the previous versions. Modifications from Version 2.4 included:

• Improved documentation of the data types
• The definition of a message profile methodology
• Better support for imaging (IHE) by means of a new segment and a new order message
• Support for orders related to blood products
• A new message that supported diagnoses/procedure messages in 'update' mode
• A new specification of claims and reimbursement messages

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