Does the distal ureteral diameter ratio (UDR) matter in the surgical management of vesicoureteral reflux in children?

Purpose: To evaluate UDR reliability, sensitivity, specificity and to identify the best treatment basing on UDR among single or double endoscopic injections and ureteral reimplantation. Methods: Data of patients affected by primary VUR and treated by endoscopic injection over a 10 years period were retrospectively analyzed. Two radiologist attributed reflux grade and UDR on voiding cystourethrogram twice and blinded. Follow-up focused on resolution after 1 or 2 endoscopic injections. Relation between UDR, reflux grade and outcomes were analyzed. Results: Patient enrolled were 198. Low grade VUR was present in 24.8%, grade 3 in 41.6%, grade 4–5 in 33.6%. Resolution after one injection was obtained in 88 patients; among 110 not resolved 104 cases had a second injection. Success after 2 injections was reported in 138 cases. UDR showed a higher reliability compared with reflux grade both in intra than inter-reader measurement (ICC > 90%). Success after 1 or 2 injections was reported for UDR < 0.33 and UDR < 0.47 respectively. Conclusion: UDR shows to be a more reliable measurement that allows for an objective estimation of VUR severity and prognosis. It represents a quantitative parameter that might be useful to identify patients who may benefit endoscopic or surgical treatment, avoiding unnecessary under or over-treatment.