Fetal bladder outlet obstruction diagnosed at 13-weeks' gestation.

An ultrasonographic examination revealed increased fetal bladder size as well as fetal bilateral hydronephrosis at 13-weeks' gestation. Diagnosis of the fetal urethral obstruction was made. Repeated ultrasonography was undertaken from the 13th to through 16th weeks of gestation. Percutaneous puncture with aspiration and laboratory analysis of fetal urine was performed at 15-weeks' gestation. The fetal renal function seemed not to be damaged by use of these antenatal procedures. Following induced abortion at 16-weeks' gestation, an autopsy showed that the fetal urethral obstruction was caused by a posterior valve, with no histological evidence of fetal renal dysplasia.