Endoscopic ultrasound of the colon for the differentiation of Crohn's disease and ulcerative colitis in comparison with healthy controls

Summary Background Diagnosis of inflammatory bowel disease ( IBD ) is based on clinical presentation, colonoscopy and histology. Differentiation of Crohn's disease ( CD ) and ulcerative colitis ( UC ) can be difficult in some patients. Endoscopic ultrasound ( EUS ) provides high resolution images of the gastrointestinal wall ( GI ) and may be an alternative to differentiate CD / UC . Aim EUS of the GI layers in patients with IBD and healthy controls ( HC ) for the differential diagnosis of UC / CD in a prospective, blinded study. Methods Consecutive patients with CD , UC or HC underwent EUS in the mid sigmoid colon with a forward‐viewing radial echoendoscope. Mucosal, submucosal, total wall thickness ( TWT ) and locoregional lymphnodes ( LN ) were assessed by EUS in a blinded fashion. TWT was correlated with macroscopic IBD scores and histological inflammation scores. Results Total wall thickness of 61 HC was 1.71 ± 0.02 mm, and 3.51 ± 0.15 mm in n = 52 with active IBD . In patients with active UC significant thickening of the mucosa was observed but nearly normal submucosa and m.propria. In active CD significant thickening of the submucosal layer was seen with nearly normal mucosa and m.propria [Mucosa UC = 2.08 ± 0.11 mm, Mucosa CD = 1.32 ± 0.17 mm ( P = 0.0001); Submucosa UC = 1.01 ± 0.08 mm, Submucosa CD = 2.01 ± 0.22 mm ( P = 0.0001)]. In 73.7% of patients with active CD , but in none with UC , paracolonic lymph nodes were detected. When mucosal‐submucosal and TWT and LN s were combined, the sensitivity was 92.3% for the differentiation of active UC / CD . There was a strong correlation of TWT with histological inflammation scores ( UC : r = 0.43; CD : r = 0.69). Conclusions Increased total wall thickness has a high positive predictive value for active IBD . EUS can differentiate active UC from CD and quantify the level of colonic inflammation.