The diagnosis and course of antenatal urinary tract dilatation.

During 1980-1984 the ultrasound examination (US) performed in the third trimester revealed urinary tract dilatation in 18 foetuses. After delivery all the infants were reexamined within the first weeks with US, intravenous pyelography and micturition urethrocystography to confirm the malformation. Pelvic dilatation was seen in 12 foetuses, 5 bilaterally. The dilatation was caused by pelviureteric obstruction in 6 infants, 4 of which were operated on with dismembered pyeloplasty. In 6 infants the dilatation was caused by distal ureteric stenoses, and 5 of them were operated on. Two foetuses with dilated pelvis and ureter had distal ureteric stenosis and both were operated. Four infants with the diagnosis of unilateral multicystic kidney, confirmed postnatally, were nephrectomised. At the follow-up the kidney function was normal in 15 infants and slightly decreased in 3 infants with bilateral malformations. The antenatal US revealed pelvic dilatation, but the diagnosis of a dilated ureter was inaccurate. Prenatal urinary tract dilatation should be controlled via US shortly after delivery and, if persistent, evaluated further by means of x-ray examinations.