Long-term clinical outcome of infants with mild and moderate fetal pyelectasis: validation of neonatal ultrasound as a screening tool to detect significant nephrouropathies.

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.