Diagnostic Accuracy of Bowel Ultrasound Compared with Colonoscopy for Assessing Disease Activity in Patients with Ulcerative Colitis

Accurate assessment of disease activity is important to effectively treat ulcerative colitis (UC) which is a chronic inflammatory bowel disorder. Colonoscopy is considered the gold standard for assessing mucosal inflammation, but is limited in its use because of its invasive nature. This approach has led to the use of bowel ultrasonography as a promising non-invasive method of monitoring disease. The aim of this study was to assess the roles of bowel U/S for measuring disease activity in patients with UC and explore its relationship with the colonoscopic findings and inflammatory markers. Methods: The study involved a prospective observational study of 90 patients with confirmed ulcerative colitis, who were clinically evaluated, subjected to laboratory, bowel ultrasonography and colonoscopy examinations. Based on disease activity, Mayo Endoscopic Subscore (MES) was used. The parameters of ultrasound of the bowel wall thickness, bowel wall stratification, Doppler vascularity, hypertrophy of the mesenteric fat, enlargement of the lymph nodes and the presence of free peritoneal fluid were evaluated and compared with those of endoscopy. Appropriate statistical tests were used to perform correlation analyses, diagnostic performance measures and agreement statistics. Findings: Bowel wall thickening was most prevalent sonographic change (72.2%) and Doppler vascularity the next most prevalent type (66.7%). Bowel wall thickness, Doppler scores, and the number of patients that showed loss of wall stratification were significantly greater in patients with active disease (MES 2–3) compared to patients with inactive or mild disease. The overall accuracy of bowel ultrasonography was very good with a sensitivity of 91.4%, and a specificty of 84.4%, an area under the receiver operating characteristic curve of 0.93. There was a significant degree of agreement between the two methods (Cohen's κ = 0.79, P < 0.001) for substantial agreement. There were significant positive correlations between bowel ultrasound finding, inflammatory markers (CRP and ESR) and Mayo Endoscopic Score. Bowel ultrasonography is an accurate, safe, non-invasive imaging method of great value, which highly corresponds with endoscopic disease activity and inflammatory markers. It may be a worthwhile instrument to be used in routine assessment and serial evaluation of patients with UC and would help to minimize the need for repeat invasive colonoscopic examinations.