P0987Bowel Wall Thickness and Vascularization Predict Improvement of Bowel Urgency in Ulcerative Colitis

Abstract Background Bowel urgency is one of the most burdensome symptoms in patients with ulcerative colitis (UC), often persisting even when endoscopic inflammation improves. Although intestinal ultrasound (IUS) and transperineal ultrasound (TPUS) are non-invasive tools capable of assessing rectal and colonic inflammation, their relationship with bowel urgency remains unclear.The aim of this study is to evaluate the association between ultrasound findings, endoscopic activity and bowel urgency in patients with moderate-to-severe UC who are initiating advanced therapy. Methods This retrospective study included patients with active UC who underwent clinical assessment, IUS, and TPUS, along with ileocolonoscopy, both at baseline and after 24 ± 4 weeks of advanced therapy. Ultrasound parameters included bowel wall thickness (BWT), layer-specific thickness, wall stratification, vascularization, and Milan Ultrasound Criteria score of rectal walls assessed by transperineal imaging. Correlation between ultrasound findings, bowel urgency (Numeric Rating Scale, NRS), and endoscopic Mayo subscore (eMS) was evaluated using Spearman’s rank correlation coefficient (r). Results A total of 49 patients were included in this interim analysis. At baseline, 80% of patients reported moderate-to-severe bowel urgency (median NRS 7 IQR 6–8). Both BWT (r = 0.62, p 0.001) and vascularization (r = 0.55, p 0.001) showed strong correlation with urgency severity. Significant correlations were also observed between TPUS parameters and eMS (r = 0.64 for BWT; r = 0.59 for vascularization, p 0.001). After 24 weeks, 64% of patients showed clinical improvement in urgency (median NRS reduction −3 points). Among all ultrasound parameters, vascularization showed the most frequent improvement, occurring in 70% of clinical responders by week 24. A post-treatment BWT 3.3 mm was associated with clinically meaningful improvement in urgency (PPV 79%, NPV 71%). The ROC analysis at 24 weeks identified a BWT cut-off of 3.3 mm for predicting persistent urgency (AUC 0.80). Conclusion Ultrasound parameters, in particular BWT and vascularization, demonstrate strong correlations with bowel urgency and endoscopic activity in UC. Vascularization emerges as the most frequent indicator of sonographic response, whereas achieving a BWT 3.3 mm predicts improvement in urgency. These findings support the role of IUS/TPUS as complementary tools in guiding treatment optimization and escalation in patients with persistent clinically meaningful urgency despite the initiation of advanced therapy. Conflict of interest: Bezzio, Cristina: No conflict of interest Dal Buono, Arianna: No conflict of interest Mrs. Migliorisi, Giulia: No conflict of interest Gabbiadini, Roberto: No conflict of interest Loy, Laura: No conflict of interest Privitera, Giuseppe: No conflict of interest Ferretti, Silvia: No conflict of interest Masoni, Benedetta: No conflict of interest Armuzzi, Alessandro: No conflict of interest