Fetal urinary tract obstructions: prenatal diagnosis--prenatal and postnatal therapy

A retrospective study was conducted comprising 78 cases of fetal urinary tract obstructions diagnosed by ultrasound. Thirteen of the obstructions were subvesical and 65 supravesical. In only one fetus with a subvesical obstruction leading to megacystis was a puncture of the fetal bladder performed--in the 17th week of gestation--resulting in restitution of the bladder to its normal size. In all of the remaining fetuses the kidneys, lungs, and bladder changes had already reached an advanced stage by the time the ultrasound diagnosis was made. In the 65 fetuses with supravesical urinary tract obstructions in utero puncture to relieve a rapidly developing hydronephrosis only seemed advisable in two cases. All of the prenatal diagnoses were confirmed postpartum with the exception of two Potter IIa kidneys, which had been interpreted as being hydronephrosis. The time and method of postnatal management are described. The results of the study indicate that in utero intervention is only indicated in the very rare case. Nearly all of the supravesical obstructions remained unchanged, some even for months. In these cases there was no evidence of cystic-dysplastic renal changes after delivery.