HL7

Abbreviation · Development

Definitions

  1. Health Level Seven, both a standards organisation and the family of standards it publishes for exchanging clinical and administrative data between healthcare systems. The name refers to the seventh, application layer of the OSI model. HL7 version 2, dating from 1989, remains the most widely deployed: messages are made of segments such as MSH for the header and PID for patient identification, with fields separated by pipes and components by carets, and they flow between lab, admissions, and billing systems through interface engines. Version 2 is flexible to the point that every site's dialect differs slightly, which is why integration work is so labour-intensive. HL7 version 3 and its Clinical Document Architecture tried a stricter XML model with limited uptake. FHIR, Fast Healthcare Interoperability Resources, is the modern standard, exposing resources such as Patient and Observation through RESTful APIs in JSON or XML, and US regulations now require certified health IT to offer FHIR APIs.

    In plain English: A standard format for sending medical information between hospital systems — like a common language so different healthcare software can talk to each other.

    Example: "Parsing HL7 v2 messages is like reading a telegram written by someone who hates you."

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