P0858Intestinal Ultrasound in Monitoring and Predicting Outcomes in Ulcerative Colitis - A Systematic Review

Abstract Background Intestinal ultrasound (IUS) is increasingly used for monitoring ulcerative colitis (UC), but its predictive value is not fully defined. This systematic review evaluated the ability of IUS parameters and scores to predict short- and long-term treatment response, remission, and adverse outcomes in hospitalised and outpatient UC populations. Methods A systematic review was conducted according to Cochrane and PRISMA guidelines. MEDLINE and Embase were searched for prospective studies assessing IUS as a predictor of clinical or endoscopic response, remission, relapse, or adverse outcomes in adult UC. Two reviewers independently performed screening, data extraction, and QUADAS-2 assessment. Results 18 prospective studies were included: 10 outpatient studies and 7 involving hospitalised patients treated with intravenous corticosteroids (IVCS). In hospitalised patients, bowel wall thickness (BWT) was the most consistent predictor of treatment failure, rescue therapy, colectomy, and clinical response. Baseline BWT showed variable performance, but once IVCS was initiated, early BWT change within 48–72h was the strongest marker of disease trajectory. Non-responders had higher BWT and smaller reductions. A BWT ≥4mm, absolute reduction ≤1mm, or relative reduction ≤20% at 48h reliably identified patients needing rescue therapy. Colectomy risk was similarly predicted: BWT 3mm at 48h was associated with no colectomies, whereas BWT ≥4mm or persistently elevated BWT at day 6 markedly increased risk. Other sonographic features (loss of haustration, increased vascularity) added supplementary but less consistent value.In outpatients, BWT also demonstrated the strongest predictive accuracy. BWT ≤3.6 mm at 2 weeks and 3.0mm at 6 weeks were associated with early endoscopic remission. Dynamic changes—≥20–30% relative reduction or ≥ 2–3mm absolute reduction—predicted clinical or endoscopic response. Persistent BWT 3.5mm or minimal reduction (20% or 1mm) indicated low likelihood of long-term remission. Composite vascularity-based indices, particularly the Milan Ultrasound Criteria (MUC), strengthened prediction: MUC ≤4.3 or ≥ 2-point reduction at 12 weeks predicted long-term remission, while MUC ≥7.7 indicated high risk of treatment failure or colectomy. Conclusion BWT consistently emerged as the strongest IUS predictor of UC treatment outcome. Early BWT change within 48–72h in hospitalised patients and absolute BWT values at 2–6 weeks in outpatients showed high predictive accuracy for response, remission, and colectomy. Composite indices incorporating vascularity further improved prediction. These findings support incorporating IUS into early treatment-response algorithms and underscore the need for standardised cut-offs and multicentre validation. Conflict of interest: Ms. Josefsen, Sabrina: No conflict of interest Larsen, Tobias: None Wilkens, Rune Levring: Personal Fees: Janssen, Takeda Denmark, AbbVie, Pfizer Denmark, Alimentiv Seidelin, Jakob Benedict: has received research grants from Takeda, Janssen, the Danish Research Council, and the Capital Region Denmark, and is national coordinator of studies from AbbVie, Arena Pharmaceuticals, Ely Lilly, and Boehringer Ingelheim. Burisch, Johan: Grant: Johnson & Johnson, MSD, Takeda, Tillots Pharma, BMS, Novo Nordisk Personal Fees: Celgene, MSD, Pfizer, AbbVie, Takeda, Tillots Pharma, Samsung Bioepis, BMS, Pharmacosmos, Galapagos, Zealand Pharma, Orion Pharma, Ferring, Johnson & Johnson Attauabi, Mohamed: Research grants from Novo Nordisk Fonden and Lundbeck Foundation. Personal fees from Eli Lilly, Celltrion, and Lundcbeck foundation, outside the submitted work. Wium Bjerrum, Jacob Tveiten: reports personal fees from Johnson and Johnson, Tillotts, Pfizer, and Nautilus Scientific.