Imperforate hymen with bilateral hydronephrosis: an unusual emergency department diagnosis.

Imperforate hymen is a rare diagnosis to make in the emergency department and important to treat immediately. Hydronephrosis is a known but rare complication of an imperforate hymen. We present the case of a premenstrual adolescent with an undiagnosed imperforate hymen complaining of increasing abdominal pain. The article discusses the history, physical examination, evaluation, differential diagnosis, ultrasound findings, complications, and prompt surgical treatment necessary.