Objective: To assess the long-term outcome of infants with mild and moderate fetal pyelectasis and to determine the predictive value of neonatal ultrasound imaging in identifying significant nephrouropathies.
Study design: This prospective study included 213 infants with antenatal mild to moderate pyelectasis who were followed for up to 2 years. Postnatal renal ultrasound examinations were performed at day 5 and months 1, 3, 6, 12 and 24 after birth. Voiding cystourethrography was performed in all infants.
Results: Normal or nonsignificant findings were diagnosed in 130 of 213 (61%) infants. Significant nephrouropathies were diagnosed in 83 of 213 (39%) infants. The sensitivity, specificity, positive predictive value, and negative predictive value of two successive neonatal renal ultrasound examinations performed at day 5 and 1 month to predict significant nephrouropathies were 96%, 76%, 72%, and 97%, respectively. In 102 of 213 (48%) infants with normal neonatal renal ultrasound scans, we later found only three of 102 (3%) cases with significant nephrouropathies.
Conclusions: We found in a population of infants with mild to moderate fetal pyelectasis a 39% incidence of significant nephrouropathies. Ultrasound is an excellent screening tool with high sensitivity and negative predictive value that allows avoidance of unjustified medical follow-up in patients with two normal neonatal ultrasound scans.