Endoscopy in IBD: When and How?

Endoscopy is an essential tool supporting inflammatory bowel disease diagnosis, and ileocolonoscopy is essential to the diagnostic process because it allows for histological sampling. A decent description of endoscopic lesions may lead to a correct final diagnosis up to 89% of the time. Moreover, endoscopy is key to evaluating endoscopic severity, which in both Crohn's disease and ulcerative colitis is associated with worse disease outcomes (e.g., more frequent advanced therapy requirements or more frequent hospitalizations and surgeries). Endoscopic severity should be reported according to validated endoscopic scores, such as the Mayo endoscopic subscore (MES) or the ulcerative colitis endoscopic index of severity (UCEIS) for ulcerative colitis, the Rutgeerts score for postoperative Crohn's recurrence, and the Crohn's disease endoscopic index of severity (CDEIS) or the simplified endoscopic score for Crohn's disease (SES-CD) for luminal Crohn's disease activity. The measuring of endoscopic activity has become a regulatory agency requirement to increase the objective evaluation of disease activity and drug response. In recent years, the central reviewing of endoscopic videos has become a standard for clinical trials. However, the adjudication paradigm and the type of endoscopic reading may substantially affect trial outcomes, and the reproducibility of all endoscopic scores is not perfect as they require the interpretation of intrinsically subjective images. This paper reviews and discusses the available evidence on inflammatory bowel disease endoscopy.