The multicystic dysplastic kidney and contralateral vesicoureteral reflux: protection of the solitary kidney.

The diagnosis of multicystic renal dysplasia is confirmed by a combination of sonography and radionuclide scan. If the contralateral kidney is normal by these criteria, further radiological examination is often omitted. We prospectively studied 29 patients with a diagnosis of multicystic renal dysplasia by voiding cystourethrography to determine the condition of the solitary contralateral kidney. Eight patients (28%) were found to have contralateral vesicoureteral reflux, of whom 6 had normal ultrasound examinations and would not have undergone further radiographic study based on ultrasound criteria alone. Contralateral vesicoureteral reflux in association with multicystic renal dysplasia puts solitary kidneys at risk for pyelonephritic scarring. Therefore, voiding cystourethrography should be performed as part of the initial evaluation of all infants with multicystic renal dysplasia.