Optimal Timing of Initial Postnatal Ultrasonography in Newborns With Prenatal Hydronephrosis

ABSTRACTPurpose: Conflicting data exist concerning optimal timing for initial postnatal ultrasound in newborns with prenatal hydronephrosis. To determine whether timing significantly affects the accuracy of postnatal ultrasound, we conducted a prospective study comparing ultrasound within 48 hours of birth and at 7 to 10 days of life.Materials and Methods: A total of 21 consecutive newborns with prenatal hydronephrosis were enrolled in 14 months. Prenatal hydronephrosis was defined as a pelvic diameter 4 mm. or greater before 33 weeks and 8 mm. or greater beginning at 33 weeks of gestation. Postnatal hydronephrosis was assessed using the Society for Fetal Urology grading system. Patients were subsequently followed with serial ultrasound and adjunctive imaging studies.Results: Of the 32 evaluable renal units a majority had a change in the degree of hydronephrosis between the first and second ultrasound. An increase in hydronephrosis was found in 14 (44%) renal units with an increase of 2 or greater grades ...