Comparison of diagnostic accuracy for fistulae at ultrasound and voiding cystourethrogram in neonates with anorectal malformation

Background: Recently, it has been reported that anorectal malformation with rectourethral fistula in male neonates can be managed by primary neonatal reconstruction without colostomy. To prevent urethral injury during anorectoplasty, the fistula’s location is important. To date, the use of voiding cystourethrograms to determine the presence and location of fistulas in neonates with anorectal malformations has not been studied. Objective: To compare the accuracy of ultrasound (US) and voiding cystourethrogram for determining the presence and location of fistulas in neonates with anorectal malformation. Materials and methods: We included 21 male neonates with anorectal malformation with rectourethral fistula (n=16), rectovesical fistula (n=1) or no fistula (n=4) who underwent US and voiding cystourethrogram preoperatively on the day of surgery. Fistula imaging was classified into three grades (0–2), and grades 1–2 were considered fistula positive. We compared the imaging-based location of the fistula with surgical findings. Results: US performed significantly better than voiding cystourethrogram for determining the presence of fistulas (area under the receiver operating characteristic curve, 0.90 vs. 0.71, respectively; P=0.044) (diagnostic accuracy 85.7%, 95% confidence interval [95% CI] 63.7–97.0% and 52.4%, 95% CI 29.8–74.3%, respectively). In cases with fistulas detected by either modality, the accuracy of locating the fistula by US was 50.0% (95% CI 24.7–75.3%) and by voiding cystourethrogram was 100% (95% CI: 59.0–100%). Conclusion: US accurately detected, but did not accurately locate, fistulas in neonates with anorectal malformation. When planning primary neonatal reconstruction of anorectal malformation without colostomy, voiding cystourethrogram could provide additional information about fistula location.