The biggest problem with EDI is semantics. When humans talk to each other they have ways of disambiguating the words and jargon used. Mistakes still happen.

The biggest problem with EDI is semantics. When humans talk to each other they have ways of disambiguating the words and jargon used. Mistakes still happen. Semantics are embedded at different layers of different systems and machines don't have the common sense to notice different semantic schemas. From the medical side; we had a pathology system, an ADT (admission, discharge, transfer) system, a clinical system, and a billing system. The semantics of what constitutes a demographic update of a patient record vs. an update of an encounter (visit) is bad enough when the same data may be denormalized in messages in both streams. Even with an established interchange format (HL7) each system encodes patients, their visits, their billing codes, and their results in slightly different ways. Sure; the pathology system and clinical system both understand HL7 and ICD9, but do they agree on what it means when a modifier gets added to one of the codes during an update? Or does an interface engine MITMing the connection have to generate a delete/insert in one direction to synchronize the semantic meaning in the downstream systems? Or what exactly does "gross description" mean to a pathologist vs. a clinician (not to mention a biller or admission clerk or me), not to mention the systems that are supposed to store this information in a meaningful way (it turns out the best quantifiable semantic representation of the latter is plain ASCII, or maybe a rich text formatted document).