I’ve been working on a patient data management system for my client based on inbound HL7 messages. An issue I struggled trying to figure out which identifier, as assigned by the hospital, represents the unique patient and which identifier represents the unique visit. I was initially thrown off by the name of PID.18 (Patient Account Number) to think it represents the unique patient. But as it turns out, it identifies a unique visit.
PID.3_PatientIdInternalId identifies the unique patient
PID.18_PatientAccountNumber identifies the unique visit
