Ultrasonographic pouch-perineum distance integrated into the multimodal diagnostic algorithm enables accurate early classification and surgical planning for anorectal malformation: an 11-year two-center study

PURPOSE: Accurate early classification of anorectal malformations (ARM) is essential for selecting the initial surgical strategy. This study evaluated the diagnostic performance of ultrasonographic pouch-perineum distance (PPD) measurement within a multimodal diagnostic algorithm for early ARM classification. METHODS: This two-center retrospective study included 156 patients with ARM who underwent definitive surgery between 2014 and 2024. The algorithm incorporated physical examination, meconium passage assessment, contrast imaging, and ultrasonographic PPD measurement. PPD was evaluated in patients without visible perineal fistulas. Final diagnosis was confirmed by contrast studies and intraoperative findings. RESULTS: The algorithm correctly classified ARM types in 155 of 156 patients (99.4%). Ultrasonographic PPD measurement was performed in 51 patients without visible perineal fistulas. In this subgroup, median PPD was significantly lower in L-ARM than in NL-ARM (6.5 vs. 15.0 mm, p < 0.001). ROC analysis showed excellent discrimination by PPD (AUC = 0.97); a 10-mm cutoff yielded 95.5% sensitivity and 89.7% specificity for distinguishing L-ARM from NL-ARM. CONCLUSION: Ultrasonographic PPD measurement is a useful adjunct in the early evaluation of neonatal ARM. When incorporated into a multimodal diagnostic algorithm, it can support classification in patients without visible perineal fistulas and may help guide timely surgical decision-making in selected cases.