R10.APain localized to flank

R10.A is the ICD-10-CM diagnosis code for pain localized to flank. It belongs to category R10 (abdominal and pelvic pain), block R10-R19 (symptoms and signs involving the digestive system and abdomen) and chapter 18 (symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within R10 (abdominal and pelvic pain), R10.A is specifically for pain localized to flank. Related codes cover acute abdomen (R10.0), pain localized to upper abdomen (R10.1), pelvic and perineal pain (R10.2), pain localized to other parts of lower abdomen (R10.3), other abdominal pain (R10.8) and unspecified abdominal pain (R10.9).

To report this condition, pick the subcode that matches the documentation: R10.A0 (side), R10.A1 (side), R10.A2 (side) and R10.A3 (bilateral).

The conditions in its Excludes2 note aren't part of R10.A, but may be coded alongside it if the patient has both: pain localized to other parts of lower abdomen (R10.3-) and pain localized to upper abdomen (R10.1-).

It was added in FY2026, effective October 1, 2025.