Implications of hydronephrosis in the newborn with myelodysplasia

Hydronephrosis has been reported to be present at birth in 6 to 28 per cent of newborns with myelodysplasia. It is unknown whether this hydronephrosis is secondary to abnormal in utero voiding dynamics and is truly present at birth or whether it is acquired postnatally secondary to spinal shock after back closure. We reviewed the perinatal course of 47 myelodysplastic newborns and conclude that the true in utero incidence of hydronephrosis is lower than that suggested in the literature, and that the hydronephrosis seen in many of these newborns is acquired after back closure and is transient in nature.