Primary vesicoureteral reflux detected in neonates with a history of fetal renal pelvis dilatation: a prospective clinical and imaging study.

OBJECTIVE: To assess the clinical outcome and imaging features of neonatal primary vesicoureteral reflux (VUR). STUDY DESIGN: We prospectively followed 43 infants with primary VUR identified from among a cohort of 497 infants with fetal renal pelvis dilatation. Postnatal renal ultrasound (US) examinations were performed at 5 days and 1, 3, 6, 12, and 24 months of life. Voiding cystourethrography was performed in the neonatal period and repeated at 12 and 24 months when VUR was persistent. Two radioisotopic examinations, including a 99mTc-MAG3 renogram and a plasma clearance of Cr-51 EDTA, were performed in all children with high-grade reflux. RESULTS: The incidence of primary VUR in our study group was 9%. Among the 43 patients followed, 11 (26%) had high-grade (IV-V) VUR and 32 (74%) had low-grade VUR. Resolution of reflux occurred in 2 of 11 (18%) patients with high-grade VUR and in 29 of 32 (90.6%) patients with low-grade VUR at age 2 years (P < .001). At age 2 years, 91% of the low-grade refluxing kidneys were normal on US, compared with only 35% of the high-grade refluxing kidneys. Split renal function was within normal range and single-kidney GFR was significantly increased in 13 of the 17 high-grade refluxing kidneys during follow-up. Furthermore, a strong association between dysplasia on US and poor renal function outcome was found. CONCLUSIONS: In most infants with VUR, the reflux is of low grade and resolves rapidly. In those children with high-grade VUR, spontaneous resolution is rare at age 2 years, but persistent reflux rarely impairs the maturation of renal function.

Routine voiding cystourethrography is of no value in neonates with unilateral multicystic dysplastic kidney.

OBJECTIVES: To determine if two successive ultrasound examinations could rule out the presence of clinically significant contralateral anomalies in neonates with multicystic dysplastic kidney (MCDK), thereby avoiding unnecessary voiding cystourethrography (VCUG). STUDY DESIGN: We followed 76 newborn infants with antenatally discovered MCDK. Two successive neonatal renal ultrasound examinations were performed, one within the first week and one at around 1 month of life. VCUG and isotopic studies were performed in all infants. RESULTS: Urologic anomalies of the contralateral kidney were present in 19 of 76 children (25%): vesicoureteral reflux (VUR) in 16 (21%), ureteropelvic junction obstruction in 2 (3%), and renal duplex kidney in 1 (1%). Sixty-one infants (80% of total) had normal contralateral urinary tract on the 2 successive neonatal renal ultrasound scans. Among them, 4 of 61 (7%) infants presented with low-grade VUR on VCUG that had resolved spontaneously before 2 years of age. The sensitivity, specificity, positive predictive value, and negative predictive value of two successive ultrasound scans in the neonatal period to predict contralateral urological anomalies on VCUG were 75%, 95%, 80%, and 93%, respectively. CONCLUSIONS: In infants with antenatally diagnosed MCDK, two successive normal neonatal renal ultrasound scans will rule out clinically significant contralateral anomalies, thereby rendering the need for a neonatal VCUG unnecessary.

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.

Results of systematic voiding cystourethrography in infants with antenatally diagnosed renal pelvis dilation.

OBJECTIVES: To assess the yield of neonatal renal ultrasonography as a predictor of abnormalities on voiding cystourethrography (VCUG). STUDY DESIGN: We prospectively followed 264 infants with antenatal renal pelvis dilation. Two successive neonatal renal ultrasound examinations were performed at day 5 and 1 month after birth. VCUG was performed in all infants. RESULTS: Neonatal ultrasound findings were abnormal in 190 infants (72% of total). Among them, 63 (33%) had an abnormal VCUG. The most common abnormalities were primary vesico-ureteral reflux (VUR) in 30 infants, VUR into the lower pole of a duplex kidney in 14, refluxing megaureter in 9, posterior urethral valves in 5, and ureterocele in 5. When both neonatal ultrasound findings were normal (74 infants), the VCUG showed abnormalities in only 5 (6.7%) patients (4 low-grade primary VUR and 1 posterior urethral valve). The sensitivity, specificity, positive predictive value, and negative predictive value of 2 successive ultrasound scans in the neonatal period to predict an abnormality on VCUG were 93%, 35%, 33%, and 93%, respectively. CONCLUSIONS: A normal-appearing urinary tract on 2 successive neonatal ultrasound scans rarely coexists with abnormal findings at VCUG. Therefore, in such patients, VCUG does not seem justified.