Ultrasonic features of multicystic dysplastic kidney: expanded diagnostic criteria.

The ultrasonographic features of multicystic renal dysplasia in 15 patients (14 children, 1 adult) are described with emphasis on differentiating this condition from hydronephrosis. The most useful ultrasonographic criteria for identifying multicystic kidney include: (a) the presence of interfaces between cysts (accurate in 100% of cases); (b) nonmedial location of the largest cyst (100%); (c) absence of an identifiable renal sinus (100%); (d) multiplicity of oval or round cysts that do not communicate (93%); and (e) absence of parenchymal tissue (73%). The role and usefulness of radionuclide renal scanning are also discussed. Ultrasonography followed by nuclear scintigraphy appears to be a logical diagnostic sequence in the evaluation of neonates with flank masses. Excretory urography is of value in assessing the status of the uninvolved kidney.