How to assess endoscopic disease activity in ulcerative colitis in 2022

Endoscopic remission currently represents an important therapeutic goal to reach in the management of patients with ulcerative colitis (UC). The diagnostic and prognostic role of endoscopy, which remains the gold standard for the assessment of disease activity, has been widely reported. Despite being unvalidated and suboptimal at measuring remission, the most widely used scoring system is the Mayo endoscopic subscore (MES). The UC Endoscopic Index of Severity and the UC Colonoscopic Index of Severity represent recent performing indices for the assessment of endoscopic disease activity in the field of white-light endoscopy. However, their use is still very limited, both in trials and clinical practice. The most recent Paddington international virtual chromoendoscopy score was the first validated index to assess vascular and mucosal features in UC using a virtual chromoendoscopy technique and showed good performance. This narrative review aims to describe these validated endoscopic scoring indices, focusing on the development methodology, and the strengths and weaknesses of each one in comparison with the MES for the assessment of UC activity.