Health Level Seven (HL7) refers to a set of international standards for the exchange, integration, sharing, and retrieval of electronic health information.
It plays a pivotal role in enabling interoperability among different healthcare information systems such as HIS, RIS, LIS, EMR, PACS, and others.
How Is HL7 Used in Healthcare Industry
Kosta Mitrofanskiy. Transforming Healthcare Communication: Integration of HL7 Interface Engine. Intellisoft. Published October 11, 2024. Accessed August 27, 2025. https://intellisoft.io/transforming-healthcare-communication-integration-of-hl7-interface-engine/
| HL7 Version | Description | Use |
|---|---|---|
| HL7 v2.x | Widely adopted, flexible message-based standard | Clinical messaging (lab, ADT, orders) |
| HL7 v3 | More rigid, XML-based | Less widely adopted due to complexity |
| CDA (Clinical Document Architecture) | XML-based document format | Discharge summaries, operative notes |
| CCD (Continuity of Care Document) | Based on CDA + HITSP | Patient summary for EHR exchanges |
| FHIR (Fast Healthcare Interoperability Resources) | Web-based, RESTful API standard | Modern apps, cloud-native EHR exchange |
Each message is composed of segments, which are groups of fields separated by a delimiter (usually | pipe symbol).
| Segment | Purpose |
|---|---|
| MSH | Message header |
| PID | Patient identification |
| PV1 | Patient visit |
| ORC/OBR | Order control/observation request |
| OBX | Observation/result (e.g., lab/radiology result) |
| Message Type | Event | Use Case |
|---|---|---|
| ADT (Admit/Discharge/Transfer) | A01–A08 | Patient demographics & visit info |
| ORM | Order Message | Imaging, lab, or procedure orders |
| ORU | Observation Result | Lab, pathology, or imaging result |
| DFT | Detailed Financial Transaction | Billing |
| SIU | Scheduling Information | Appointments |