Contrast-Enhanced Ultrasound in Children with Anorectal Malformations: A Radiation-Free Alternative to Fluoroscopy for Identifying Fistulae with Genitourinary Tract.

OBJECTIVES: To explore the utility of contrast-enhanced ultrasono-distal cologram (CE-US-DC) as a radiation-free modality to detect fistulae with genitourinary tract in children with anorectal malformation (ARM), compared with fluoroscopic distal cologram (F-DC) as the gold standard. METHODS: In this IRB-approved prospective study, 50 children (up to 2 years of age) with ARMs were enrolled over an 18-month period (January 2024-June 2025). All children underwent F-DC followed by CE-US-DC in the same sitting. The type of fistula and the level of communication on CE-US-DC were recorded and compared with those on F-DC. RESULTS: Rectourethral, rectovesical, rectoperineal, and rectovaginal fistulas were seen in 27/50 (54%), 1/50 (2%), 11/50 (22%), and 4/50 (8%) children, respectively, on F-DC. No fistula was seen in 7/50 (14%) children on F-DC. CE-US-DC demonstrated 100% sensitivity and 100% negative predictive value. One fistula detected on CE-US-DC yielded a specificity of 85.71% and a positive predictive value of 97.73%. CE-US-DC showed an overall accuracy of 98%. Cohen's Kappa analysis indicated perfect agreement (κ = 1.0) for most fistula types and strong agreement for rectovaginal types (κ = 0.878). ROC curve analysis showed an AUC value of 1.0 for rectourethral, rectoperineal, and rectovesical fistula, and 0.989 for rectovaginal fistula. CONCLUSION: CE-US-DC demonstrated excellent diagnostic accuracy and almost perfect agreement with F-DC, indicating high reliability and reproducibility in detecting fistulae with genitourinary tract in children with ARM. CE-US-DC has great potential as an attractive radiation-free modality in the pre-operative workup of children with ARM.