Ulcerative colitis only affects the large intestine or colon. It also only affects the inner lining of the bowel (the mucosa), causing it to ulcerate and bleed. Ulcerative colitis always starts in the rectum and can continue to extend further along the colon in a continuous fashion. It does not "skip" portions of the colon in its progression.
Common symptoms with ulcerative colitis include diarrhea, which can be associated with the loss of blood. Bowel movements may be frequent and associated with urgency and or spasm and cramping. There may be abdominal pain, fever, and weight loss.
Ulcerative colitis usually presents in the early decades of life, but can also have its initial presentation in the fifth or sixth decades of life, and on occasion in the seventh or eighth decades. Incidence of ulcerative colitis is highest in the Scandinavian countries, Great Britain and North America; it is less commonly found in Asia, Africa and South America. The disease also tends to be found amongst individuals of Jewish descent, more specifically Ashkenazi Jews. There is a slightly higher incidence of Ulcerative Colitis in females than in males.