P0820Transmural imaging with IUS refines disease monitoring even in endoscopic remission

Abstract Background Crohn’s disease (CD) monitoring traditionally relies on mucosal healing, yet transmural remission is increasingly recognized as a stronger predictor of outcomes (1) . Intestinal ultrasound (IUS) enables real-time assessment of transmural inflammation through bowel wall thickness (BWT) (2). A substantial subset of patients achieve endoscopic healing while exhibiting persistent transmural disease activity on IUS, and the clinical implications of this discordance remain uncertain. We aimed to evaluate clinical outcomes among CD patients with normal colonoscopy but abnormal transmural activity on IUS. Methods We retrospectively included adult CD patients in biologic-induced clinical and endoscopic remission who underwent colonoscopy and IUS within 3 months. Patients were categorized into two groups: those with normal colonoscopy but abnormal BWT on IUS, and those with both normal colonoscopy and normal IUS. Normal IUS was defined as BWT ≤ 3 mm (3). The primary outcome was disease escalation, defined as the need for therapy escalation, corticosteroids, hospitalization, surgery, or treatment modification. Results A total of 68 patients were included (median age 34 ± 14 years; 53% male). Disease location was 67.6% terminal ileum, 10.4% colon, and 22.0% ileocolonic. The median interval between colonoscopy and IUS was 40 days (IQR 0–89). During follow-up, 63% (43/68) experienced disease exacerbation. Median BWT was 3.0 mm (IQR 2–5) in the escalation group versus 2.1 mm (IQR 2–3.5) in the non-escalation group. Abnormal BWT was strongly associated with clinical action (64.0% vs 20.9%; p = 0.001). Maximum BWT predicted escalation with good discrimination (AUC 0.804), with an optimal cutoff of 2.9 mm (sensitivity 0.80, specificity 0.72). Patients with abnormal BWT had earlier deterioration (median ∼9 months), whereas no median deterioration was observed by 12 months in patients with normal BWT (log-rank p = 0.0056). On Cox regression, normal IUS was associated with a 66% lower hazard of clinical escalation (HR 0.34; 95% CI 0.15–0.77). Conclusion In Crohn’s disease patients in biologic-induced and endoscopic remission, IUS effectively predicts future therapy failure. A simple BWT 2.9 mm threshold identifies patients at high risk for relapse, supporting IUS as a practical, non-invasive monitoring tool for personalized management. References: 1- Fernandes SR, Rodrigues RV, Bernardo S, et al. Transmural Healing Is Associated with Improved Long-term Outcomes of Patients with Crohn’s Disease. Inflamm Bowel Dis. 2017 Aug;23(8):1403-1409. doi: 10.1097/MIB.0000000000001143. PMID: 28498158. 2- Albshesh A, Haj S, Veisman I, et al. Intestinal ultrasound measurement of bowel wall thickness can be used as a sole marker for defining anti-TNF maintenance therapy failure in Crohn’s disease. Therapeutic Advances in Gastroenterology. 2025;18. doi:10.1177/17562848251343008 3- F. Zorzi, D. T. Rubin, N. K. Cleveland, et al. Ultrasonographic Transmural Healing in Crohn’s Disease, American Journal of Gastroenterology 118, no. 6 (2023): 961–969, https:// doi.org/10.14309/ajg.0000000000002265 Conflict of interest: Dr. Hashlamoun, Muhran: No conflict of interest Heiman, Sophia: No conflict of interest Levartovsky, Asaf: Honoraria and speaker fees from: Takeda, Sanofi, Rafa Ukashi, Offir: NA Ben-Horin, Shomron: Grant: Abbvie, Takeda, Janssen, Celltrion, Pfizer, Medtronic, Galmed, OutSense Personal Fees: Advisory board and/or consulting and/or Speaker fees from Abbvie, Takeda, Janssen, Celltrion, Pfizer, GSK, Ferring, Novartis, Roche, Gilead, NeoPharm, EviNature, Galmed, Medial Earlysign, BMS, Pfizer, Falk, Medtronic and Eli Lilly. Options/stocks in Predicta Med, Evinature, Galmed, Alma Therpeautics. Kopylov, Uri: Grant: Takeda, Janssen,Abbvie, Medtronic, Ely Lilly Other: Takeda, Janssen, Ely Lilly, Roche, Celtrion, Abbvie, Medtronic, CTS, Pfizer, BMS- speaker and advisory fees Carter, Dan: Personal Fees: speakers fees from Takeda, Janssen, Abbvie, Taro and Lapidot Tarp and consultancy fees from Takeda Taro and Lapidot Albshesh, Ahmad: received speaking and lecturing fees from Takeda, Janssen and abbvie