P0511Intestinal bowel ultrasound changes at 48 hours associates with steroid response in Acute Severe Ulcerative Colitis

Background Ιntestinal bowel ultrasound (IBUS) is a non-invasive bedside tool for monitoring ulcerative colitis (UC)¹. However, data on its role in acute severe UC (ASUC) are sparse. The International Bowel Ultrasound Segmental Activity Score (IBUS-SAS), a score initially validated for Crohn’s disease, has recently been proposed as a reference score for UC as well². Our aim was to determine if IBUS changes after 48h of intravenous steroids are associated with response to therapy in hospitalized patients with ASUC. Methods We prospectively included all patients with ASUC (based on Truelove and Watts criteria) admitted at our centre from 06/2024 to 10/2025. Ultrasound parameters [Bowel wall thickness (BWT) and IBUS-SAS] of the most affected bowel segment were recorded before treatment initiation and at 48±24 hours. Treatment response was evaluated using the Oxford criteria on day 3 and the need for rescue therapy. Results Fourteen patients [women:32%, age:36(22,59)] were included, with 6 (43%) being non-responders. Baseline demographics, duration of disease, prior biologics, laboratory exams(hemoglobin, platelets, fibrinogen, albumin, CRP), and UCEIS score at admission did not differ between responders and non-responders. Moreover, BWT and IBUS-SAS at admission were similar between the two groups. At 48±24h, responders and non-responders differed significantly in median BWT (3.65 vs 5.05 mm; p = 0.01), IBUS-SAS (35 vs 68.2; p = 0.016), relative BWT change (-23.5% vs 0%; p = 0.004) and relative IBUS-SAS change (-29.4% vs 0.96%; p = 0.028). Conclusion Early decreases in BWT and IBUS-SAS, but not baseline values, were associated with short-term steroid response in patients with ASUC, which confirms previous findings³. Larger,multicentre studies should define usable cut-offs and assess performance. References: 1. de Voogd F, van Wassenaer EA, Mookhoek A, et al. Intestinal Ultrasound Is Accurate to Determine Endoscopic Response and Remission in Patients With Moderate to Severe Ulcerative Colitis: A Longitudinal Prospective Cohort Study. Gastroenterology. 2022;163(6):1569-1581. doi:10.1053/j.gastro.2022.08.038 2. Innocenti T, Rocco C, Balena E, et al. The use of International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) in patients with ulcerative colitis: applicability and comparison with other ultrasound scores. J Crohns Colitis. 2025;19(5):jjaf050.doi:10.1093/ecco-jcc/jjaf050 3. Ilvemark J, Wilkens R, Thielsen P, et al. Early Intestinal Ultrasound Predicts Intravenous Corticosteroid Response in Hospitalised Patients With Severe Ulcerative Colitis. J CrohnsColitis. Nov 23 2022;16(11):1725-1734. doi:10.1093/ecco-jcc/jjac083 Conflict of interest: Dr. Neonaki, Antonia: No conflict of interest Karatzas, Pantelis: No conflict of interest Koutsoumpas, Andreas: I have nothing to diclare Mouziouras, Dimitrios: No conflict of interest Papaxoinis, Konstantinos: No conflict of interest Vlachogiannakos, Jiannis: No conflict of interest Papatheodoridis, George V.: No conflict of interest