The definition of colitis is inflammation of the colon. There are many different ways that inflammation can present and manifest itself. There are also many different causes of inflammation of the colon or colitis. Ulcerative colitis is an ulcerative inflammatory process of the colon. Ulcerative colitis and Crohn's disease are the two disorders that make up Inflammatory Bowel Disease, or IBD. They are chronic colitis', with ulcerative colitis involving only the colon, and Crohn's disease involving either colon, small intestine or both colon and small intestine. In Ulcerative colitis, the colon is inflamed and ulcerated and very abnormal looking at colonoscopy. The disease is a systemic one, that frequently causes fever and abdominal pain in addition to diarrhea and rectal bleeding. Additionally, other organs of the body can be involved, and include inflammatory processes of the eye, skin, liver and joints. Treatment includes anti-inflammatories specific to the colon (Asacol, Colazol, Pentasa), steroids (Prednisone, Entocort), immunosuppressive agents (6-mercaptopurine, Azathioprine) and biologic agents (Remicade, Humira, Cimzia). (Find more drug information here)
Microscopic colitis is an inflammatory process of the colon, in which to the eye at colonoscopy, the colon appears normal. Under the microscope, there are two variants that can be found. In the first, collagenous colitis, the pathology is a thickening of the layer of collagen of the colon, as well as an increase in the amount of inflammatory cells. In the second, lymphocytic colitis, there is an increase in the number of intra-epithelial lymphocytes in the colon wall. The result is fairly significant watery, non-bloody diarrhea. As the colon will look normal to the eye, biopsy at colonoscopy must be performed to make the diagnosis. Like ulcerative colitis, the cause of microscopic colitis is unknown. The disease will typically respond to anti-diarrheals such as Lomotil and Immodium. If not, Asacol usually works well, but some patients will need steroids such as Entocort.
Ischemic colitis is an inflammatory process of the colon as a result of a lack of blood flow to the arteries that supply blood to the colon. It typically occurs in patients over the age of 60, and is more common in those patients with cardiovascular disease. Certain medications also have a higher incidence of ischemic colitis and include oral contraceptives and cocaine use. Patients will typically present with abdominal pain and rectal bleeding. A CT scan typically shows a thickening of the affect areas of colon, which are most commonly the splenic flexure and descending colon. Treatment is supportive, with bowel rest, intravenous hydration, and depending on the degree of symptoms, intravenous antibiotics. Colonoscopy should be performed a month or so after the acute episode to rule out colon cancer. Unlike Ulcerative colitis and microscopic colitis, ischemic colitis is not a chronic condition. While symptoms at times can recur, especially in the elderly patient, they usually do not.
In summary, ulcerative, ischemic and microscopic colitis can usually be distinguished from one another by history and physical examination. Imaging studies such as CT scan be at times be necessary. Colonoscopy, as long as patients are stable, and can be prepped without an increased risk of perforation will usually be confirmatory. Biopsies, however, will frequently be needed to confirm a microscopic colitis. Not all colitis is the same, so if you are experiencing any of these symptoms, check with your gastroenterologist.