Correlation between anteroposterior renal pelvic diameter and vesicoureteral reflux in congenital hydronephros

Introduction: One of the most common findings in prenatal evaluation is congenital hydronephrosis. The correct diagnosis is of great value. This study was conducted to find the correlation between Anteroposterior Renal Pelvic Diameter (APD), which is detected by postnatal ultrasonography, and Vesicoureteral Reflux (VUR) in neonates and infants with congenital hydronephrosis. Therefore, this study was accompolish to determine whether invasive imaging such as voiding cystourethrography (VCUG) can be avoided especially in mild hydronephrosis. This imaging causes concern and anxiety for parents because of insertion of urinary catheter and radiation exposure of patients. Materials and Methods: In this study, neonates or infants with postnatally confirmed congenital hydronephrosis, referred to nephrology clinic during 2016-2018, were included. They were examined by ultrasonography, and their APD was measured. Infants with hydronephrosis persisting after birth underwent VCUG. Results: Out of 122 cases, 99 cases (81.1%) were male. Thirty-four cases with VUR (28 male) were detected. Mean APD in patients with VUR and without VUR was 19.51±12.50 and 12.15±5.68 respectively, which showed a significant difference between two groups (P value of 0.012). No correlation between grade of VUR and APD was found (P = 0.301). In addition, ROC curve showed that APD could be an acceptable variable for predicting VUR in male cases (AUC: 0.738 and P = 0.003). The best cut-of-point for APD predicting VUR in male cases was 10.5 mm (sensitivity: 76.8% and specificity: 52.9%). Conclusion: Postnatal APD in ultrasonography has a significant correlation with the presence of the VUR in male cases.