Retrocaval ureter: report of two cases and literature review.

Retrocaval ureter is a rare congenital anomaly in which the ureter passes behind, and is compressed by, the inferior vena cava. Its etiology is assumed to be abnormal embryologic development of the inferior vena cava as a result of atrophy failure of the right subcardinal vein in the lumbar portion. We report two cases of retrocaval ureter and review the relevant literature. One patient was a 7-year-old boy who presented with right flank pain. The other was a 40-year-old male who was found to have right hydronephrosis accidentally on abdominal sonography during a health examination. Both underwent retrograde pyelography which showed the typical S-shape of a retrocaval ureter. Abdominal computerized tomography and magnetic resonance imaging confirmed the diagnosis of retrocaval ureter. Ureteroureterostomies were performed. One patient showed focal squamous metaplasia of the ureter and the other had chronic inflammation and fibrosis. Follow-up studies showed improvement in hydronephrosis and renal function in both patients. We conclude that retrocaval ureter is a rare disorder and surgical correction is usually effective.