Summary: Background: Transabdominal ultrasound is useful to assess inflammation in patients with ulcerative colitis (UC); however, the assessment of the rectum is challenging and a barrier for its widespread use.Aim: To evaluate if transperineal ultrasound is useful for predicting endoscopic and histological findings of the rectum in UC.Methods: Fifty‐three consecutive adults with UC who required colonoscopy were included and transperineal ultrasound was performed in combination with transabdominal ultrasound within a week before or after colonoscopy with rectal biopsy. Mayo endoscopic subscore (MES) ≤1 was defined as endoscopic healing and Geboes score <2.1, Robarts histopathology index ≤6, and Nancy index ≤1 were defined as histological healing. Limberg score and bowel wall thickness were recorded with transperineal ultrasound. Faecal calprotectin was also measured.Results: Excellent correlation was confirmed between colonoscopy and transabdominal ultrasound in all segments except for the rectum. Rectal bowel wall thickness and Limberg score in transperineal ultrasound well correlated with rectal MES and histological indices. Bowel wall thickness ≤4 mm predicted endoscopic (Area under the curve [AUC] = 0.90) and histological (AUC = 0.87‐0.89) healing. In multivariable logistic regression analysis, only bowel wall thickness in transperineal ultrasound was a significant independent predictor for rectal endoscopic and histologic healing (P < 0.05) and the predictability was better than faecal calprotectin.Conclusions: Transperineal ultrasound predicts endoscopic and histological healing of the rectum. The combination of transperineal ultrasound with transabdominal ultrasound visualises the entire colorectum and is an ideal modality for the treat‐to‐target strategy.Clinical Trials Registry number UMIN000033611 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000038323).

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn’s disease (CD), is a chronic condition marked by persistent intestinal inflammation of unknown etiology. Disease onset involves genetic predisposition and environmental factors that disrupt the intestinal immune homeostasis. The intestinal microbiome and immune response play pivotal roles in disease progression. Advances in molecular therapies and early interventions have reduced surgery rates; however, colorectal cancer (CRC) remains a significant concern, driven by chronic inflammation. In UC, the risk of UC-associated neoplasia (UCAN) increases with disease duration, while CD patients face elevated risks of small intestine, anal fistula, and anal canal cancers. Endoscopic surveillance is advised for UCAN, but optimal screening intervals remain undefined, and no established guidelines exist for CD-associated cancers. UCAN morphology often complicates detection due to its flat, inflammation-blended appearance, which differs pathologically from sporadic CRC (sCRC). UCAN is frequently surrounded by dysplasia, with p53 mutations evident at the dysplasia stage. IBD-associated gastrointestinal cancers exemplify inflammation-driven carcinogenesis with distinct molecular mechanisms from the adenoma-carcinoma sequence. This review explores the epidemiology, risk factors, clinical and pathological features, current surveillance practices, and molecular pathways underlying inflammation-associated cancers in IBD.

Introduction: A large proportion of small bowel lesions in Crohn’s disease (CD) may exist beyond the reach of ileocolonoscopy and there is no gold standard imaging modality to screen them, suggesting the need for optimal biomarkers. We aimed to compare the usefulness of C-reactive protein (CRP), faecal calprotectin (FC), and leucine-rich alpha-2 glycoprotein (LRG) in determining small bowel lesions of CD. Methods: This was a cross-sectional observational study. CRP, FC, and LRG were prospectively measured in patients with quiescent CD who underwent imaging examinations (capsule or balloon-assisted endoscopy, magnetic resonance enterography, or intestinal ultrasound) selected by the physician in clinical practice. Mucosal healing (MH) of the small bowel was defined as a lack of ulcers. Patients with a CD activity index >150 and active colonic lesions were excluded. Results: A total of 65 patients (27, MH; 38, small bowel inflammation) were analysed. The area under the curve (AUC) of CRP, FC, and LRG was 0.74 (95% confidence interval: 0.61–0.87), 0.69 (0.52–0.81), and 0.77 (0.59–0.85), respectively. The AUC of FC and LRG in a subgroup of 61 patients with CRP <3 mg/L (26, MH; 32, small bowel inflammation) was 0.68 (0.50–0.81) and 0.74 (0.54–0.84), respectively. The cut-off of 16 μg/mL of LRG showed the highest positive predictive value of 1.00 with specificity of 1.00, while negative predictive value was highest (0.71) with sensitivity of 0.89 at the cut-off of 9 μg/mL. Conclusion: LRG can accurately detect and/or exclude the small bowel lesions with two cut-off values.