Masked ureteral duplication with ectopic ureter detected by magnetic resonance imaging.

The usefulness of magnetic resonance imaging (MRI) in the detection of a masked duplex kidney system is described. A 9 year old girl was admitted to our hospital for urinary incontinence. She was found to possess an ectopic ureter associated with complete ureteral duplication. She had been evaluated for incontinence at several hospitals, but neither ultrasound sonography nor intravenous pyelography detected any abnormalities. Only cystoscopic examination and MRI detected the anomalies. Partial nephroureterectomy resolved the patient's incontinence. MRI is useful for the detection of ureteral duplication and should be used on cases in which this condition is suspected, prior to performing invasive procedures.