Bowel ultrasound and mucosal healing in ulcerative colitis

Background and aim: Mucosal healing (MH) after short-term medical treatment is being considered as an important step in the therapeutic work-up of inflammatory bowel disorder (IBD) patients due to the potential prognostic role of MH in predicting disease outcome. However, IBD patients are reluctant to be re-endoscoped during follow-up; therefore, there is a need for non-invasive alternative index of MH which can replace endoscopy in clinical practice. We evaluated bowel ultrasound (US) as a surrogate of colonoscopy in a series of consecutive patients with active ulcerative colitis (UC).

Patients and methods: 83 patients with moderate to severe UC requiring high-dose steroids were initially recruited; endoscopic severity of UC was graded 0-3 according to Baron score, and US severity was also graded 0-3 according to the colonic wall thickening and the presence of vascular signal at power Doppler. 74 patients responsive to steroids and then maintained on 5-ASA compounds were followed up with repeated colonoscopy and bowel US at 3, 9 and 15 months from entry. Concordance between clinical, endoscopic and US scores at various visits was determined by kappa statistics. Multiple unconditional logistic regression models were used to assess the predictivity of Truelove, Baron and US scores measured at 3 and 9 months on the development of a UC relapse (Baron score 2-3) at 15 months.

Results: An inconsistent concordance was found over time between 0 and I Baron scores and Truelove score (weighted kappa between 0.38 and 0.94), with high and consistent concordance between 0 and I Baron scores and US scores (weighted kappa between 0.76 and 0.90). On logistic regression analysis, a moderate/severe Baron score, regardless of their Truelove score, at 3 months was associated with a high risk of endoscopic activity at 15 months (OR 5.2; 95% CI: 1.6-17.6); similarly, patients with severe US scores (2-3) at 3 months had a high risk of severe endoscopic activity at 15 months (OR 9.1; 95% CI: 2.5-33.5).

Discussion: In expert hands bowel US may be used as a surrogate of colonoscopy in evaluating the response to high-dose steroids in severe forms of UC. US score after 3 months of steroid therapy accurately predicts clinical outcome of disease at 15 months.