Incidence and Diagnostic Performance of Postnatal Ultrasound for Presacral Masses in Pediatric Patients With Anorectal Malformation

Objectives To determine the incidence of presacral masses in patients with anorectal malformations (ARMs) and evaluate the diagnostic performance of ultrasound to detect presacral masses during the neonatal period. Methods Pediatric patients with ARM underwent ultrasonography during the neonatal period, and their magnetic resonance imaging (MRI) results were reviewed. The presence or absence of a presacral mass was assessed employing ultrasonography and compared with MRI results using the Clopper–Pearson method. The type of ARM (low/not‐low) and the presence or absence of sacral anomalies were compared between patients with and without a presacral mass using Fisher's exact test. Results The incidence of presacral masses in our study cohort was 4.6% (5/109). Ultrasound diagnostic performance for detecting presacral masses had an accuracy of 98.2% (95% confidence interval (CI): 93.5–99.8), sensitivity of 60% (95% CI: 14.7–94.7), specificity of 100% (95% CI: 96.5–100), positive predictive value of 100% (95% CI: 29.3–100), and negative predictive value of 98.1% (95% CI: 93.4–99.8). ARM type and presence or absence of sacral anomalies were significantly different between the presacral mass and without presacral mass groups (low/not‐low = 5/0 vs 47/57, P = .022; and presence/absence of sacral anomalies = 3/2 vs 18/86, respectively, P = .048). Conclusions The incidence of presacral masses in pediatric patients with ARM was low (5%). Although the positive predictive value was reliable, ultrasonography performed during the neonatal period was not sensitive. Therefore, sonographers should pay attention when evaluating patients with low‐type ARMs accompanying sacral anomalies to avoid overlooking them.