Clinical Impact of Endoscopic Evaluation of the Small Bowel in Crohn's Disease

Background: The STRIDE-II position statement has established endoscopic healing as the long-term target of treatment for inflammatory bowel disease, and ileocolonoscopy is considered the gold standard for assessment of endoscopic healing. However, precise assessment of endoscopic healing cannot be achieved by ileocolonoscopy alone in patients with Crohn's disease (CD). Summary: Approximately 70-80% of patients with CD have small bowel disease, and intestinal complications develop more frequently in the small bowel than in the colorectum. The recent advent of small bowel capsule endoscopy and balloon-assisted enteroscopy has not only clarified the higher incidence of proximal small bowel lesions but has also revealed the presence of such lesions as a possible risk factor for poor disease outcomes. Evidence has shown that the therapeutic efficacy of biologics may differ between the small bowel and the colorectum. In the postoperative setting, it was recently recognized that intestinal lesions other than those at the anastomotic site should be carefully monitored considering the risk of postoperative recurrence. However, there are some obstacles to implementing endoscopic assessment of the entire small bowel and colorectum. Inflammatory biomarkers might play important roles in such scenarios, but the predictive value of biomarkers for small bowel endoscopic healing remains controversial. Key Messages: Endoscopic assessment of the small bowel is indispensable for improvement of the long-term outcome of CD. The validity of endoscopic healing and transmural healing as long-term targets remains to be fully elucidated.