In outpatient data, the patient reason for visit (DX_Visit_Reasonn) should be coded for all unscheduled visits. DX_VISIT_REASONn is an ICD-9-CM diagnosis code and up to three codes are allowed.
Diagnoses are compared to a list of ICD-9-CM codes valid for the discharge date. Anticipation of or lags in response to official ICD-9-CM coding changes are permitted for discharges occurring within a window of time around the official ICD-9-CM coding changes (usually October 1). A year window (six months before and six months after) is allowed. Invalid diagnoses are set to "invl".
For data beginning in the fourth quarter of 2015, the visit reason is stored in the data element I10_Visit_Reasonn to indicate the implementation of the ICD-10-CM/PCS coding system.