Ulcerative colitis is a chronic, or long-lasting, disease that causes inflammation and sores, called ulcers, in the inner lining of the large intestine, which includes the colon and the rectum. Normally, the large intestine absorbs water from stool and changes it from a liquid to a solid. In UC, the inflammation causes loss of the lining of the colon, leading to bleeding, production of pus, diarrhea, and abdominal discomfort.

Microscopic colitis is inflammation of the bowel that is only visible using a microscope. Microscopic colitis is a type of inflammatory bowel disease (IBD), which refers to a group of conditions that causes inflammation in the bowel due to an excessive build-up of white blood cells in the bowel lining. Microscopic colitis is less severe than other types of IBD because it does not lead to cancer and rarely requires surgery. However, microscopic colitis can cause considerable pain and discomfort.

Crohn’s disease is a disease that causes inflammation, or swelling, and irritation of any part of the digestive tract. The part most commonly affected is the end part of the small intestine, called the ileum.

In Crohn’s disease, inflammation extends deep into the lining of the affected part of the G.I. tract. Swelling can cause pain and can make the bowel empty frequently, resulting in diarrhea. Chronic inflammation may produce scar tissue that builds up inside the intestine to create a stricture. A stricture is a narrowed passageway that can slow the movement of food through the intestine, causing pain or cramps.

Crohn’s disease is an inflammatory bowel disease (IBD), the general name for diseases that cause inflammation and irritation in the intestines. Crohn’s disease can be difficult to diagnose because its symptoms are similar to other intestinal disorders, such as ulcerative colitis and other IBDs, and irritable bowel syndrome. For example, ulcerative colitis and Crohn’s disease both cause abdominal pain and diarrhea. Crohn’s disease may also be called ileitis or enteritis.

For more information about IBD click here to download the IBD Fact Book from The Crohn's & Colitis Foundation of America.