Preoperative diagnosis of unilateral multicystic kidney with hydropelvis

We present 2 patients with congenital unialteral multicystic kidney disease with hydropelvis. In the first patient the diagnosis was made by precutaneous puncture of a renal cyst followed by injection of contrast medium; in the second the diagnosis was confirmed by percutaneous puncture of the renal pelvis and injection of contrast medium, although an earlier ultrasonic examination had been strongly suggestive. Since in this condition the cysts and the renal pelvis communicate, either can be punctured to make the diagnosis. The procedures herein described are definitive for the diagnosis and should be followed whenever the urologist desires such a diagnosis.