Bowel Wall Thickness Cutoff Value for Assessing Inflammatory Bowel Disease Activity Using Intestinal Ultrasonography in Children

Abstract

Background and Aims: Intestinal ultrasonography (IUS) is a noninvasive tool for assessing bowel inflammation. In adults, a bowel wall thickness (BWT) cutoff of 0.30 cm is used to indicate inflammation, but children do not have a widely accepted value. We propose an optimal BWT cutoff value for children. Methods: We performed 144 IUS examinations during 2019-2024 in 133 children within 30 days before to 7 days after colonoscopy. Assessed values for the BWT from the terminal ileum to the rectum were paired with colonoscopy findings at each segment (n = 809 pairs). The cutoff value for detecting inflammation was explored with receiver operating characteristic (ROC) analysis. Results: In children ≥6 years old IUS demonstrated excellent accuracy for detecting moderate/severe inflammation (area under the curve [AUC] 0.907) but poor accuracy for mild inflammation (AUC 0.690) or in children <6 years old (AUC, 0.667). The adult cutoff (0.30 cm) missed 32% of inflammation in children. In children ≥6 years old, a BWT cutoff of 0.27 cm detected 85% of moderate/severe and 43% of mild inflammation. Lower cutoff values (0.24 cm) were more optimal for girls and children weighing <40 kg. Conclusions: Although IUS is an excellent tool for detecting moderate/severe bowel inflammation, this method showed limited accuracy in children <6 years old. The adult BWT cutoff missed over 30% of bowel inflammation in children. BWT cutoff of 0.27-0.30 cm in boys and 0.23-0.25 cm in girls and/or children <40 kg indicated active gut inflammation.