A 32-week prenatal sonogram of a male fetus followed for hydronephrosis reveals increasing bilateral hydronephrosis, a dilated bladder, and new-onset marked oligohydramnios. What is your recommendation?
Posterior urethral valves leading to bilateral hydronephrosis with oligohydramnios is the most likely etiology, and this situation potentially represents a rare urologic indication for induction of labor or fetal intervention.
1- Fetal lung maturity should be evaluated with a lecithin/sphingomyelin amniotic fluid ratio prior to a final recommendation.
2- If fetal surgical intervention is considered, fetal renal function should be estimated by the urinary sodium chloride, osmolality, and Beta 2 microglobulin obtained by fetal bladder aspiration.
3- A high-grade obstruction of a single system also requires a similarly rapid response. The outcomes for fetal intervention with respect to improvement of renal function are mixed.