OBR-31 in HL7 v2: A Field Guide to Reason for Study
OBR-31 carries the clinical justification for an order — the kind of field that's supposed to support medical necessity checks and prior-authorization workflows. In practice it arrives as anything from a clean coded diagnosis to a hastily typed free-text note, and systems that expect only the former reject or garble the latter.
OBR-31 is the thirty-first field of the HL7 v2 OBR segment — the Reason for Study, carrying the clinical indication or justification for the ordered test, which can repeat and can be coded, free text, or both.
What this field contains
Example
OBR-31 carries R/O anemia, a free-text clinical indication for the order. Synthetic order — not a real patient.
Where this trips people up
Medical-necessity or prior-authorization logic that expects OBR-31 to always contain a clean, codeable diagnosis breaks as soon as a clinician orders through a workflow that only supports free text, which is common in urgent or add-on order scenarios. The field passes HL7 validation either way since both forms are legal, so the failure shows up downstream as a rejected claim or a stalled auth request rather than as a parsing error at intake. Test both coded and free-text variants of this field explicitly.