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Colitis is swelling (inflammation) of the large intestine (colon).

Colitis can have many different causes, including:

• Acute and chronic infections
• Inflammatory disorders (ulcerative colitis, Crohn's colitis, lymphocytic and collagenous colitis)
• Lack of blood flow (ischemic colitis)
• Past radiation to the large bowel

For more information about a specific type of colitis see:

• CMV colitis (a viral infection of the colon)
• Crohn's disease (regional enteritis)
• Cryptosporidium enterocolitis
• Ischemic colitis
• Necrotizing enterocolitis
• Pseudomembranous colitis
• Ulcerative colitis

Symptoms can include:

• Abdominal bloating
• Abdominal pain
• Bloody stools
• Dehydration
• Diarrhea
• Increased intestinal gas

The health care provider can diagnose colitis by inserting a flexible tube into the rectum (flexible sigmoidoscopy or colonoscopy) and evaluating specific areas of the colon. Biopsies taken during these tests may show changes related to inflammation.

Other studies that can identify colitis include:

• Abdominal CT scan
• Abdominal MRI
• Abdominal x-ray
• Barium enema

The prognosis varies with each disease. See particular conditions listed above.

• Bleeding
• Hole in the colon
• Toxic megacolon
• Sore (ulceration)

Call your health care provider if you have symptoms such as:

• Abdominal pain
• Blood in the stool
• Expanded (distended) abdomen

Prevention depends upon the cause of colitis. See the specific condition.