P0400Normal point-of-care intestinal ultrasound predicts sustained remission in clinical relapse of Inflammatory Bowel Disease

Abstract Background Intestinal Ultrasound (IUS) is emerging as the preferred imaging modality in Inflammatory Bowel Disease (IBD), yet its current position among available investigative tools remains uncertain. This study aims to define its optimal role in evaluating patients with clinical and biochemical relapse. Methods This is a retrospective review of all IBD patients who underwent Point of Care (POC) IUS in Singapore General Hospital IBD outpatient clinic from November 2024 to October 2025. The indications for POC IUS were divided into investigation of clinical relapse (PRO2≥1), biochemical relapse (C-reactive Protein 5mg/L and/or Faecal Calprotectin 250ug/g) or both. Baseline demographics, findings of POC IUS and subsequent management plan/follow up were captured. A normal (negative) IUS of the colon is defined as bowel wall thickness (BWT) 3mm (4mm for rectum) without colour Doppler signal (CDS). Results A total of 101 patients who fulfilled inclusion criteria were identified. (Table 1) Of this, 31 patients (30.7%) had clinical only relapse, 34 patients (33.7%) had biochemical only relapse and 36 (35.6%) had both clinical and biochemical relapse. There was a significant association between indication of IUS and IUS findings (X2=6.04, p = 0.049) with combined clinical and biochemical relapse demonstrating the highest probability of having a positive IUS finding (OR = 4.14, 95% CI 1.82-9.45, p = 0.001) whereas clinical-only (OR = 0.44, 95% CI 0.15-1.33, p = 0.144) and biochemical-only relapse (OR = 0.27, 95% CI 0.09-0.79, p = 0.016) had lower probabilities. In multivariable logistic regression model (adjusted for gender, type of IBD, and age) presence of clinical and biochemical relapse were significant associated with findings of positive POC IUS (OR = 2.97, 95% CI 1.12, 7.84, p = 0.028). Among 27 patients with clinical or biochemical-only relapse and normal IUS, 10 achieved clinical and biochemical remission and 5 endoscopic remission while 5 showed persistent disease activity (3 biochemical, 2 endoscopic). A normal IUS among patients with clinical-only relapse was associated with sustained remission (NPV 100%, 95% CI 76,2-100.0%). Kaplan-Meier curves showed significant difference in time-to-event for documented clinical, biochemical, or endoscopic activity between these two groups (log-rank X2 = 4.57, p = 0.033, Figure 1). Conclusion Point of care IUS demonstrates highest diagnostic yield when both clinical and biochemical relapses are present. A normal IUS in patients with clinical-only relapse is predictive of sustained remission supporting its role as a rule-out tool in this subgroup. Conflict of interest: Dr. Lim, Chong Teik: No conflict of interest Tay, Shu Wen: No conflict of interest Tan, Yi Yuan: No conflict of interest Leong, Justin: No conflict of interest Salazar, Ennaliza: No conflict of interest Tan, Teck Kiang Malcolm: No conflict of interest