Types and Causes of Colitis

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While the most common symptom of colitis is colon inflammation, many other signs and symptoms may accompany the inflammation. The nature of accompanying symptoms often depends on the cause of the colitis. The disease itself has a range of different causes. Causes of colitis include acute or chronic infection, inflammatory disorders such as Crohn’s disease, ischemia, and prior radiation treatment.

Ulcerative Colitis

This condition is a type of inflammatory bowel disease which mainly affects the rectum and large intestine. The disease usually begins causing inflammation in the rectum, and this may spread to the large intestine over time. Repeated inflammation can eventually cause build-up of scar tissue, followed by death of rectal and intestinal tissue. The causes of ulcerative colitis are unknown.

Crohn’s Colitis

The main symptom of this type of colitis is chronic inflammation of the gastrointestinal tract. While the intestines are most often affected, any part of the GI tract, from the esophagus to the rectum, may become inflamed. The exact cause of Crohn’s disease is not known, but it is currently believed that the disease is an autoimmune disorder.

Ischemic Colitis

Ischemia is a condition which is caused by sudden reduction or complete stop in the flow of blood to a particular area. Ischemic colitis, therefore, occurs when blood flow to the colon is suddenly reduced or halted. The blood flow reduction is usually temporary but the after-effects may be permanent. Risk factors of ischemic colitis include congestive heart failure, diabetes, history of stroke, low blood pressure, and vascular disease.

Infectious Colitis

This category of colitis can be caused by infection of the colon with one of several different types of bacteria and viruses. Possible causes of infectious colitis include:

Pseudomembranous colitis occurs when Clostridium difficile overgrows in the large bowel. This species of bacteria is part of the normal gut microflora, but following a course of antibiotics it may overgrow to such an extent that it causes inflammation of the colon. Risk factors include advanced age, immune system suppression (such as that caused by chemotherapy), and recent antibiotic use.

Necrotizing Enterocolitis affects mainly newborn babies who are premature or sick. The main characteristic of this type of colitis is death of tissue lining the intestinal wall. The cause is thought to be growth of intestinal bacteria; however some experts suggest a role for decreased blood flow to the bowel. Risk factors include premature birth, blood transfusion, and feeding of concentrated formula.

Cytomegalovirus Colitis: The cytomegalovirus is extremely common, and most people are exposed to it at some point in their lives; however most will remain asymptomatic. In people who have weakened immune systems, the virus can cause serious disease, including colitis-type symptoms. Risk factors include AIDS, chemotherapy, bone marrow or organ transplant, and immunosuppressant medications.


Crohn’s & Colitis Foundation of America

National Digestive Diseases Information Clearinghouse at the National Institute of Diabetes and Digestive and Kidney Diseases. Ulcerative Colitis

Singh, Jagvir, MD. Colitis at eMedicine

Wedro, Benjamin, MD. Colitis at eMedicineHealth