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-totarget strategy. Clinical Trials Registry number UMIN000033611

Summary Background Bowel ultrasonography is a non‐invasive imaging tool that can repeatedly monitor ulcerative colitis (UC) activity. Aim This study aimed to determine whether early transabdominal or transperineal ultrasonography changes can predict subsequent clinical response to induction therapy in patients with UC. Methods This single‐centre prospective study explored ultrasonographic predictors for clinical remission (patient‐reported outcome‐2 ≤ 1 with no rectal bleeding subscore) at week 8 in patients with active UC who underwent induction therapy, in comparison with faecal calprotectin and C‐reactive protein (measured at baseline, week 1 and week 8). Predictive factors were assessed using multivariable regression models and receiver‐operating‐characteristic curve analysis. Results A total of 100 patients were analysed, of which 54 achieved remission at week 8. Baseline biomarker and ultrasonographic‐parameter values were not predictive of remission. Contrastingly, change from baseline to week 1 in rectal bowel wall thickness measured using transperineal ultrasonography was an independent predictor of remission by week 8 (adjusted odds ratio is associated with a 1‐mm decrease: 1.90 [95% confidence interval, 1.22–2.95]). In a subgroup analysis of the patients who did not achieve remission in 1 week, the predictive value of change in rectal bowel wall thickness remained high (AUC = 0.77 [95% confidence interval, 0.61–0.88]). Conclusion Improvement in rectal bowel wall thickness measured using transperineal ultrasonography at week 1 predicts treatment success and potentially facilitates decision making during the early course of induction therapy in UC.

Background Bowel ultrasonography is a non-invasive imaging tool that can repeatedly monitor the activity of ulcerative colitis (UC). This study aimed to determine whether early changes in bowel ultrasonographic findings could predict subsequent clinical response to induction treatment in patients with ulcerative colitis. Methods This single-center prospective study compared ultrasonographic findings with fecal calprotectin, and C-reactive protein (measured at baseline, week 1, and week 8) in predicting remission (patient-reported outcome-2 ≤ 1 with no rectal bleeding subscore) at week 8 in active UC patients who initiated the remission-induction treatments. Predictive factors were assessed using multivariate regression models and a receiver operating curve analysis. Results A total of 100 patients were analysed, of which 54 achieved remission at week 8. Baseline values of biomarkers, and ultrasonographic parameters were not predictive of remission. Bowel wall thickness and bowel wall flow at baseline and week 1 were also not sufficiently predictive. By contrast, changes from baseline to week 1 in bowel wall thickness in the rectum measured by transperineal ultrasonography was an independent predictor of remission by week 8 (adjusted odds ratio associated with 1 mm decrease: 1.90 (95% confidence interval 1.22–2.95)). Predictive value of changes in rectal bowel wall thickness remained high for clinical improvement even among patients who did not achieve remission in 1 week. Conclusion Improvement in rectal bowel wall thickness measured by transperineal ultrasonography at week 1 predicts treatment success and thus would help decision making during the early course of induction treatment in UC.