Multicystic dysplastic kidney and pelviureteric junction obstruction.

Two infants with nonfunctioning antenatally detected multicystic dysplastic kidneys developed acute renal failure in conjunction with pelviureteric obstruction of the contralateral kidney at 9 and 14 months of age, respectively. The initial postnatal ultrasounds had shown mild pelvic dilatation in both cases. Clinicians need to be aware of the possibility of late obstruction.