Last updated on:October 2nd, 2022
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Ulcerative colitis (UC) is a chronic inflammatory bowel condition with a relapsing and remitting disease course that often presents with hematochezia, abdominal pain, rectal urgency and tenesmus, among other symptoms. UC begins in the rectum and extends proximally. Though it primarily affects the lower gastrointestinal (GI) tract, multiple extra-gastrointestinal systems can be affected.
UC is classified according to the Montreal classification. This describes UC by disease extent according to the area of the gastrointestinal tract affected. E1 or proctitis is disease limited to the rectum; E2 is left-sided disease distal to the splenic flexure; and extensive colitis or E3 is disease extending proximal to the splenic flexure.
The development of UC is influenced by the interaction between external environmental factors (so-called “exposomes”), immune system dysregulation, epithelial and mucosal barrier defects in the colon, dysbiosis, and disruption of GI homeostasis in a genetically susceptible individual.
UC's disease process involves epithelial and mucosal dysfunction in the colon which allows the infiltration of luminal gut bacteria. This initiates an inflammatory cascade within the colonic mucosa, leading to gut dysbiosis. Depleted goblet cells, a porous mucus barrier and inflammatory cytokines facilitate this process. Immune dysregulation in the form of T helper cells leads to the perpetuation of cellular apoptosis and inhibits mucosal healing. Though an autoimmune link has been considered due to the detection of anti-colon, perinuclear anti-neutrophil cytoplasmic antibodies and anti-neutrophil cytoplasmic antibodies, these have not been found in high enough concentrations to be causative.
Though UC can occur at any age, most cases are in the 15-40-year age group. UC has been found to be at a higher incidence in westernized, developed countries, although rates in developing countries are increasing.
UC has many complications. These include, but are not limited to: