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

Colitis is an inflammation of the large intestine that can be caused by many different disease processes. These processes include acute and chronic infections, inflammatory disorders (ulcerative colitis, Crohn's colitis, lymphocytic and collagenous colitis), lack of blood flow (ischemic colitis), and history of radiation to the large bowel.

For more information about a specific type of colitis see:

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

Symptoms can include abdominal pain, diarrhea, dehydration, abdominal bloating, increased intestinal gas, and bloody stools.

Colitis may be identified by flexible sigmoidoscopy or colonoscopy  -- in both of these tests, a flexible tube is inserted in the rectum, and specific areas of the colon are evaluated. Biopsies taken during these tests may show changes related to inflammation.

Other studies that can identify colitis include:

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