HL7 Interoperability

A practitioner's path through health-data interoperability across the full HL7 family — from the wire-level v2 messages that still run most production interfaces, through v3/CDA documents, to modern FHIR APIs — plus the terminology and operations knowledge real integration work demands.

Who it's for. Technical and clinical-adjacent professionals integrating healthcare systems. Assumes general computing literacy; introduces all domain concepts from first principles.

7 courses · 51 lessons

Path

1. HL7 v2 Fundamentals

   Start at the wire level. The v2 message format is still the backbone of hospital integration, so it grounds every concept that follows.

   Foundations

   • What HL7 Is and Why It Exists
   • Anatomy of an HL7 v2 Message
   • How v2 Messages Are Exchanged — Acknowledgments and MLLP

   Message Structure in Depth

   • The MSH Header, Field by Field
   • Data Types — from ST and NM to XPN, XAD, CX, and CWE
   • Components, Subcomponents, and Repetition
   • Z-Segments and Local Customization
   • Escaping, Encoding, and Character Sets

   Conformance and Versions

   • The v2 Version Lineage (2.1 to 2.9) and Backward Compatibility
   • Optionality, Cardinality, and Loose Conformance
   • Message Profiles and Conformance Constraints

2. HL7 v2 Messaging in Practice

   Apply the fundamentals to the message types that carry real clinical workflows: admissions, orders, results, scheduling, and billing.

   Patient Administration

   • ADT and the Patient Lifecycle (A01 to A08 and Merges)
   • The PID, PV1, and NK1 Segments in Clinical Context

   Orders and Results

   • Order Workflow — ORM/OMG and the ORC and OBR Segments
   • Results — ORU and the OBX Observation Segment
   • Units, Reference Ranges, and Abnormal Flags in OBX

   Scheduling, Documents, and Finance

   • Scheduling with SIU
   • Medical Documents with MDM
   • Charges and Billing with DFT

   Query and Batch

   • Query and Response Paradigms (QBP/RSP)
   • Batch and File Protocols (BHS and FHS)

3. Healthcare Terminologies and Coding

   Messages move data, but meaning lives in codes. A shared grounding in SNOMED CT, LOINC, ICD, and RxNorm before the standards that bind them.

   Why Terminologies

   • Codes versus Free Text — Semantic Interoperability Revisited

   The Major Systems

   • SNOMED CT — Concepts, Relationships, and Expressions
   • LOINC — Naming Observations and Lab Tests
   • ICD-10-CM and ICD-10-PCS — Diagnoses and Procedures
   • RxNorm and Medication Coding

   Using Terminologies in Messages

   • Value Sets, Bindings, and the CWE Data Type
   • Mapping and Maintenance Pitfalls

4. HL7 v3 and the Clinical Document Architecture

   The model-driven reaction to v2. CDA documents remain widely exchanged and introduce the RIM thinking that informs FHIR.

   The v3 Reaction

   • Why v3 and the Reference Information Model (RIM)

   Clinical Document Architecture

   • CDA Document Structure — Header and Body
   • Levels of CDA and the C-CDA Templates
   • Where CDA Is Used (and Where It Isn't)

5. FHIR Fundamentals

   The modern, web-API standard. Resources, REST, and search are where most new interoperability work happens today.

   The FHIR Model

   • Why FHIR — Resources as the Unit of Exchange
   • Anatomy of a Resource (JSON, ids, and metadata)
   • References, Contained Resources, and Bundles
   • Data Types and Extensions

   The RESTful API

   • CRUD Interactions and the FHIR HTTP API
   • Search — Parameters, Chaining, and Includes
   • Operations and the CapabilityStatement

   Terminology in FHIR

   • CodeSystem, ValueSet, and the $expand and $validate-code Operations

6. FHIR Implementation

   Real FHIR work is conformance work: profiles, implementation guides, SMART on FHIR, and bulk data.

   Conformance

   • Profiles, Extensions, and StructureDefinition
   • Implementation Guides and US Core

   Apps and Access

   • SMART on FHIR and OAuth2 Scopes
   • Bulk Data Export (Flat FHIR)

   Validation and Testing

   • Validating Resources Against Profiles

7. Interoperability in Practice

   Tie it together with the operational layer: integration engines, troubleshooting, security, and go-live — applicable beyond HL7 alone.

   The Integration Engine

   • What Interface Engines Do (Mirth, Rhapsody, Cloverleaf)
   • Transformation, Routing, and Filtering

   Reliability and Troubleshooting

   • Error Handling, Retries, and Dead-Letter Queues
   • Diagnosing Lost and Duplicate Messages

   Security, Privacy, and Go-Live

   • Consent, Minimum Necessary, and HIPAA Touchpoints
   • Interface Testing and Go-Live Readiness