Postnatal Imaging May Be Unnecessary When Prenatal Hydronephrosis Resolves

Prenatal hydronephrosis (renal pelvic diameter ≥4 mm prior to 33 weeks gestation) is a common anomaly that often resolves before birth but may persist throughout pregnancy. Researchers reviewed postnatal renal imaging for 165 children with prenatal hydronephrosis, defined as temporary (renal pelvic diameter <7 mm at or after 33 weeks gestation) in 69 (60% boys) and persistent (renal pelvic diameter ≥7 mm at or after 33 weeks gestation) in 93 (73% boys).

Postnatal recurrence of hydronephrosis was significantly less frequent among patients with temporary than with persistent prenatal hydronephrosis (44% vs. 78%). Children with persistent prenatal hydronephrosis had greater renal pelvic diameter, both on prenatal and postnatal ultrasound. Only …