Fetal urethral obstruction: US evaluation.

To further elucidate antenatal sonographic features of fetal urethral obstruction and attempt to determine which features might predict subsequent outcome, 40 in utero cases were reviewed. All fetuses had dilated urinary bladders and/or thickened bladder walls; in 47.5% of fetuses a dilated posterior urethra was seen. Only 15 fetuses (37.5%) survived the neonatal period. Survivors tended to present later in gestation than nonsurvivors. Poor prognostic indicators included oligohydramnios (20 of 21 subsequently died), absence of caliectasis (20 of 24 died), a large amount of urine ascites (five of six died), and dystrophic bladder wall or peritoneal calcification (five of five subsequently died). Conversely, 14 of 19 (74%) fetuses without definite oligohydramnios survived the neonatal period.