The importance of mucosal healing in ulcerative colitis

Ulcerative colitis (UC) is an idiopathic condition of the colon, in which acute and chronic inflammation results in an injured bowel. Chronic inflammatory damage, confined exclusively to the mucosa of the colorectum, is the hallmark of the disease. The inflammation is characteristically superficial in nature and appears to begin in the rectum with variable extension to more proximal portions of the colon. This inflammation, and subsequent loss of function, is the mechanism underlying the typical symptoms of UC. Although there may be more systemic symptoms, the majority of the symptoms of UC are derived from an inflamed rectum and due to loss of compliance of the rectum, loss of sensation of stool, as well as symptoms of tenesmus incomplete evacuation, urgency, and bleeding with hematochezia. The healed bowel can result in the resolution of symptoms and has been associated with disease control and resolution, but traditional clinical assessment of UC involves symptom management primarily, with the assumption that when bleeding and urgency are improved, adequate disease control has been achieved. However, resolution of bowel inflammation is not always manifest as improved or resolved symptoms, and improved symptoms are not always associated with a healed bowel or durable disease control. This chapter reviews the importance of mucosal healing as a prognostic marker and therapeutic endpoint in UC.