Ulcerative colitis is a chronic inflammatory disease in which a part or the whole of the mucosa of the large bowel becomes diffusely inflamed and may ulcerate, as a result of which the patient suffers from diarrhoea which may be bloody.

• usually starts in the rectum and extends proximally in a symmetrical, circumferential, and uninterrupted pattern (1,2)  
• may affect parts of the colon, or its entire mucosal surface
• characterised by exacerbations and remissions (1).

The cause of ulcerative colitis is unknown but genetic, immunological, dietary, and psychological factors have all been implicated.

The highest incidence of this disease is in adulthood, although it may occur in childhood

According to the Montreal classification, the extent of ulcerative colitis can be classified as:

• ulcerative proctitis – inflammation is limited to the rectum (proximal extent of inflammation is distal to the rectosigmoid junction)
• left sided UC (distal UC) – inflammation limited to a proportion of the colorectum up to the splenic flexure
• extensive UC (pancolitis) - involvement extends beyond the splenic flexure (3)

Reference:

• (1) Stange EF et al. European evidence-based Consensus on the diagnosis and management of ulcerative colitis: Definitions and diagnosis. Journal of Crohn's and Colitis (2008) 2, 1–23
• (2) Kornbluth A et al. Ulcerative colitis practice guidelines in adults: American College Of Gastroenterology, Practice Parameters Committee. Am J Gastroenterol. 2010;105(3):501-23
• (3) Satsangi J et al. The Montreal classification of inflammatory bowel disease: controversies, consensus, and implications. Gut. 2006;55(6):749-53