Sonography of fetal urinary tract anomalies.

Experience with 13 cases and a review of 41 cases in English literature indicate that anomalous development of the fetal urinary system can be detected in utero using sonography. Anomalies not compatible with extrauterine life (bilateral renal agenesis, infantile polycystic and bilateral multicystic kidney disease) have distinctive sonographic features that can be detected early enough to allow elective termination. Megacystis, either as a primary finding or secondary to urethral obstruction, can be detected and usually portends a poor fetal outcome. Obstruction at the ureterovesical junction has a distinctive sonographic appearance, but ureteropelvic junction obstruction cannot be differentiated from some cystic renal lesions, particularly when it is unilateral. Even when a precise diagnosis cannot be established in utero, the detection of a fetal renal anomaly may significantly affect obstetric and neonatal management of the benefit of both mother and fetus.