Early Reduction in Rectal Wall Thickness on Transperineal Ultrasound Predicts Mucosal Healing in Ulcerative Colitis

Introduction Intestinal ultrasound (IUS) is a valuable tool for assessing short-term responses to treatment of ulcerative colitis (UC). Nevertheless, no prior reports on IUS use, earlier than week 6-14, are known for predicting long-term endoscopic responses. This study evaluated whether IUS (transabdominal and transperineal) at week 1 can predict long-term clinical–endoscopic remission (CER) and histo-endoscopic mucosal improvement (HEMI) following advanced therapies. Methods This was a post hoc analysis of a prospective study examining the predictive value of IUS at baseline and weeks 1 and 8 after the initiation of advanced therapy in patients with active UC. CER and HEMI were defined based on the Mayo endoscopic subscore and Geboes score assessed from colonoscopy after >14 weeks. The predictive values of the IUS for CER and HEMI were assessed using a receiver operating characteristic (ROC) analysis. Results Of the 69 patients, 15 (21%) achieved CER and 11 (16%) achieved HEMI. At week 1, reduction in rectal bowel wall thickness (Δrectal BWT) was significantly greater in the CER and HEMI groups than those without these improvements (CER: 1.1 ± 0.7 vs. -0.1 ± 1.4, P < 0.01; HEMI : 1.2 ± 0.7 vs. 0.0 ± 1.4, P < 0.01). However, Δrectal BWT at week 8 did not differ between the groups. ΔRectal BWT at week 1 accurately predicted both CER (AUC 0.75; 95% CI 0.60-0.86; P = 0.02) and HEMI (AUC 0.79; 95% CI 0.65-0.88; P = 0.02) with high accuracy. Conclusion Assessing the rectal wall thickness at week 1 is valuable for predicting advanced therapy-induced CER and HEMI in patients with UC. Clinical Trials Registry Number UMIN000032422 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi? recptno=R000036970).