P0401Intestinal Ultrasound Accurately Detects Endoscopic Activity in Pediatric Ulcerative Colitis: A Prospective Bicentric Validation Study

Background Endoscopic assessment for evaluating disease activity in pediatric ulcerative colitis (UC) is invasive, resource-intensive, and particularly burdensome in children. Intestinal ultrasound (IUS) represents a promising non-invasive alternative. This study evaluated the diagnostic accuracy of three IUS indices (MUC, UC-IUS, and Civitelli) in detecting endoscopic activity in pediatric UC, and assessed whether combining IUS with fecal calprotectin or PUCAI improves performance. Methods In this prospective bicentric study, 75 pediatric UC patients underwent IUS within 7 days of colonoscopy at two tertiary centers. Disease activity was defined as Mayo Endoscopic Subscore (MES) ≥2. Ultrasound indices (MUC, UC-IUS, Civitelli) were calculated. Receiver operating characteristic (ROC) analysis, Youden-optimized thresholds, and logistic regression models incorporating fecal calprotectin or PUCAI were used to assess diagnostic accuracy. Results Moderate-to-severe endoscopic activity (MES ≥2) was present in 73.3% of patients. All IUS indices significantly discriminated active from inactive disease (p < 0.001). MUC showed the highest accuracy (AUROC 0.80; 95% CI 0.677–0.923), with a Youden-optimal threshold of 4.2 (sensitivity 0.71, specificity 0.85). UC-IUS demonstrated high specificity (0.90) but lower sensitivity (0.54) (AUROC 0.793; 95% CI 0.658–0.928). The Civitelli score was more sensitive (0.82) but less specific (0.60) (AUROC 0.763; 95% CI 0.622–0.904). Combining IUS scores with fecal calprotectin or PUCAI increased AUROCs to 0.83–0.89. Accuracy improved further in severe disease (MES 3). Differences between centers reflected variations in baseline disease severity. Conclusion MUC, UC-IUS, and Civitelli scores accurately detect endoscopic inflammation in pediatric UC, with MUC showing the most balanced performance. Integrating IUS with fecal calprotectin or PUCAI enhances diagnostic precision, supporting its role in non-invasive monitoring and treat-to-target strategies in pediatric UC. References: 1. Fanizzi F, Zilli A, D’Amico F, Danese S, Allocca M. Revolutionizing UC monitoring: The emerging role of intestinal ultrasound. Curr Opin Pharmacol. 2025 Sep 27;85:102578. doi: 10.1016/j.coph.2025.102578. Epub ahead of print. PMID: 41130177. 2. Dolinger MT, Aronskyy I, Spencer EA, et al. Early intestinal ultrasound response to biologic and small molecule therapy is accurate to predict treat-to-target endoscopic outcomes in children with ulcerative colitis: results from the prospective super sonic-UC study. J Crohns Colitis. 2025 May 8;19(5). 3. Kucharzik T, Taylor S, Allocca M, Burisch J, Ellul P, Iacucci M, Maaser C, Baldin P, Bhatnagar G, Ben-Horin S, Bettenworth D, Chavannes M, Driessen A, Flanagan E, Furfaro F, Maconi G, Karmiris K, Kellar A, De Kock I, Katsanos K, Kopylov U, Lu C, Nardone OM, Noor NM, Novak K, Borralho Nunes P, van Rheenen P, Rimola J, Rosini F, Rubin D, Scharitzer M, Stoker J, Uzzan M, Vavricka S, Verstockt B, Wilkens R, Zidar N, Zilli A, Yanai H, Feakins R. ECCO-ESGAR-ESP-IBUS Guideline on Diagnostics and Monitoring of Patients with Inflammatory Bowel Disease: Part 1. J Crohns Colitis. 2025 Jul 3;19(7):jjaf106. doi: 10.1093/ecco-jcc/jjaf106. PMID: 40741688. Conflict of interest: Prof. Dr. Massironi, Sara: No conflict of interest Mulinacci, Giacomo: No conflict of interest Zuin, Giovanna: No conflict of interest Civitelli, Fortunata Sabrina: No conflict of interest Pirola, Lorena: Consulting fees and participation on advisory board: Abbvie. Honoraria for presentations, speakers bureaus and educational events: Pfizer, Janssen, Takeda. Receipt of equipment and materials: Celltrion. Support for attending meetings and/or travel: Abbvie, Johnson and Johnson, Takeda, Pfizer, Giuliani, Ferring, Eli Lilly, Alfasigma, Cadigroup Tassistro, Elena: No conflict of interest Terranova, Cecilia: No conflict of interest Albini, Maria: No conflict of interest Invernizzi, Pietro: No conflict of interest Dinelli, Marco Emilio: No conflict of interest Danese, Silvio: Personal Fees: AbbVie, Alimentiv, Allergan, Amgen, Applied Molecular Transport, AstraZeneca, Athos Therapeutics, Biogen, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Celltrion, Dr Falk Pharma, Eli Lilly, Enthera, Ferring Pharmaceuticals Inc., Gilead, Hospira, Inotrem, Janssen, Johnson & Johnson, Morphic, MSD, Mundipharma, Mylan, Pfizer, Roche, Sandoz, Sublimity Therapeutics, Takeda, Teladoc Health, TiGenix, UCB Inc., Vial, Vifor Lecture fees from Abbvie, Amgen, Ferring Pharmaceuticals Inc., Gilead, Janssen, Mylan, Pfizer, Takeda Maino, Marta: No conflict of interest