Ectopic supernumerary kidney. Functional assessment using radionuclide imaging.

A three-year old male presented with severe hydronephrosis secondary to posterior urethral valves; a pelvic supernumerary kidney was discovered postoperatively. Radionuclide imaging assisted in the management of this patient by providing estimates of relative renal function. A report of the case and a complete summary of the literature concerning this unusual duplication anomaly follows.