Urometrocolpos associated with retroiliac ureter.

We report on an 8-year-old girl who presented clinically with an acute abdomen. Examination revealed a left hypoplastic kidney with its ureter draining into the lower segment of the vagina, which was closed by an imperforate hymen. Initially, we thought that pressure by the urometrocolpos on the right ureter caused right hydronephrosis. Subsequently, it was found that the right ureter followed a retroiliac course and was compressed by a U-shaped iliac artery loop at the ureteral crossing. The iliac artery extended to the level of the second lumbar vertebra.