Ulcerative colitis is characterized by recurring episodes of inflammation limited to the inner lining of the colon.
It generally involves the rectum and can extend in a continuous fashion to involve other portions of the colon.
Inflammation can occasionally extend to involve the end portion of the small bowel.
Ulcerative colitis can be classified according to the extent of involvement:
ulcerative proctitis – limited to the rectum
proctosigmoiditis – affecting the rectum and the end portion of the colon (sigmoid colon)
left-sided ulcerative colitis – affecting the colon on the left hand side of the body
pancolitis – involvement extending beyond the colon on the left hand side of the body.
Inflammatory bowel disease (IBD)
Inflammatory bowel disease refers to a group of conditions where the bowel becomes inflamed.
These conditions include ulcerative colitis and Crohn’s disease.
In 10% of cases there may be features of both ulcerative colitis and Crohn’s disease and these cases are termed indeterminate colitis.
The cause of these conditions is not yet fully understood, but is thought to relate to the bacteria living in the bowel and the immune response. Genetic factors have also been implicated.