Acute urinary retention as the presentation of imperforate hymen.

Acute urinary retention is unusual in children and is usually a candidate for visiting the emergency department upon initial discovery. We report a 12-year-old girl who complained of acute urinary retention. Ultrasonography demonstrated a large echogenic mass over the vagina and mild dilation of the uterus. Imperforate hymen associated with hematocolpos and hematometrium was diagnosed. Cruciate hymenotomy was performed. The symptoms resolved after treatment. Adolescent girls who complain of urinary symptoms with no previous menstruation should have their external genitalia examined in order to rule out the possibility of imperforate hymen as the cause of acute urinary retention.