The natural history of prenatal hydronephrosis with normal amounts of amniotic fluid.

Thirteen cases of fetal hydronephrosis associated initially with normal volumes of amniotic fluid were diagnosed by maternal sonography. No invasive procedures were done in utero. Postnatal evaluation demonstrated 8 neonates with urinary tract obstruction and 5 normal neonates. Long-term followup of these 13 patients revealed that 12 are healthy and have normal renal function. The exception is a child whose amniotic fluid decreased during pregnancy. Our data suggest that fetuses with normal volumes of amniotic fluid do well. Treatment should be limited to frequent prenatal sonography and subsequent early postnatal evaluation. Caution should be exercised with the diagnosis of hydronephrosis, since 5 of our patients had false positive findings. In the rare instances when oligohydramnios develops during pregnancy fetal intervention may be warranted.