OBJECTIVE The purpose of this study was to determine the incidence of ureteric obstruction (UB) and requirement for Cohen antireflux surgery (CAS) after DefluxⓇ treatment (DT) for vesicoureteric reflux (VUR). METHODS Between 2011 and 2017, 494 ureters (VUR severity ≤ grade III: N=291 or >grade IV: N=203) were treated by DT at a mean age of 4.5 (range: 0.2-24) years. Epidural Catheter Assistance (ECA) was used to exclude UB by injecting diluted indigo carmine solution (1-3mL) into an epidural catheter inserted into a ureter after DT and confirming dye flow within 15min. ECA+: N=181 ureters; ECA-: N=313 ureters. RESULTS In ECA+, UB was detected in 5/181 (2.7%) ureters (grade II: N=1, III: N=3, and IV: N=1) treated by leaving the ECA catheter in situ overnight (N=4) or double J stent (DJS) insertion for 1month (N=2). After mean follow-up of 1.9years, one grade III DJS case has residual grade II VUR. In ECA-, 3/313 (0.9%) cases developed UB. One resolved, and one required DJS. CAS was required for 17/494 (3.4%) ureters and hindered by DT in 5/17 (29.4%) ureters. All are sequelae-free after mean follow-up of 1.8years. CONCLUSIONS UB may be more frequent than reported (3.3% versus 0.6%-1.8%). ECA identifies potential UB. METHODS Treatment study. METHODS Level III.