Hong Kong HA HL7 Integration

The brief

A clinical system needed to exchange data with Hospital Authority systems rather than have staff re-key it. That meant HL7 v2 messaging over MLLP, correct handling of admission, order and result flows, resilience when an endpoint goes quiet, and patient data handled to the standard healthcare demands.

What I did

• Mapped the message set field by field — ADT for admissions, transfers and discharges, ORM for orders, ORU for results — onto the application's own data model.
• Stood up an interface engine to normalise HL7 segments, validate required fields and translate code sets between the two sides.
• Implemented MLLP transport with acknowledgements, retries and back-off, so nothing is silently dropped when a system is unavailable.
• Built a message log and replay tool: any exchange can be traced end to end and re-sent after an outage.
• Handled patient identifiers under Hong Kong's PDPO — least-privilege access, retention rules and audit trails on every read.
• Ran structured UAT across normal and edge-case messages before go-live, then monitored the first live cutover closely.

Outcome

• Demographics, orders and results move automatically instead of being re-typed
• Failed messages surface immediately with a clear path to replay them
• Every exchange is auditable for clinical and compliance review