Definitions

Accession Number: A string which uniquely identifies the order from other orders in a particular filling application.
Requisition Number: It uniquely identifies an order among all orders from a particular ordering application.

FileResult_CMS Order Reconciliation Parameter Definitions

VisitNumberEXT (Parameter 11) Required
- External (non-Enterprise EHR clinical database) identifier for a visit.
- Used for finding an existing visit
AccessionNumber (Parameter 50) Required
- External identifier for the result
- Must be unique at the test (for example CHEM12) level
OrderNumberEXT (Parameter 51) Optional
- Enterprise EHR clinical database-generated identifier for an order associated with this result
- Used to match result with an order generated in Enterprise EHR or through an Inbound Order Interface
ReqNumberExt (Parameter 124): Optional
- Enterprise EHR clinical database-generated identifier for an requisition associated with this result

Visit Number: Has to be unique per interface source ID. If we generate it, the interface source id is zero. This must be unique forever. Used to group the results, for time, and to attach to/create a new encounter. Results coming in will generate a new task for each visit number.
Accession Number: The result accession number is only used for results. Should be unique from the vendor to ID a result. Encounter Date + QOClass + Accession has to be unique across the source id. The patient match is not part of this.

Currently the mapping of visit = accession + year will help prevent errors (typically from bridge) where the result is bridged to 2 different patients.
The standard of visitnumberext = accession + year will work if accessions are only reused after one year. In the case of a net new client you will have to check with the lab to see if that is accurate.