Microscopic colitis is a bowel disorder that affects the intestines. The exact cause of this condition is unknown. There are two types of this disorder: collagenous colitis and lymphocytic colitis. Chronic watery diarrhea is the primary symptom of both forms. Dietary and lifestyle changes aimed at improving diarrhea are usually the first line of treatment, with medications used if these changes alone are not enough.
Inflammatory bowel disease (IBD) is a general name for diseases that cause inflammation in the intestines. Collagenous colitis and lymphocytic colitis are two types of bowel inflammation that affect the colon (the large intestine). These two types of colitis are known as microscopic colitis. Microscopic colitis is not related to Crohn's disease or ulcerative colitis, which are more severe forms of inflammatory bowel disease. Also, microscopic colitis does not increase the risk of colon cancer.
Collagenous colitis and lymphocytic colitis are referred to as microscopic colitis, because colonoscopy usually shows no signs of inflammation on the visible surface of the colon. Instead, tissue samples from the colon must be examined under a microscope to make the diagnosis.
No precise cause has been found for microscopic colitis. Possible causes of damage to the lining of the colon are bacteria and their toxins, viruses, or nonsteroidal anti-inflammatory drugs (NSAIDs). Some researchers have suggested that microscopic colitis results from an autoimmune response, which means that the body's immune system is destroying cells for no known reason.
Microscopic colitis symptoms include:
- Chronic watery, nonbloody diarrhea. The diarrhea may be continuous or come and go in episodes.
- Abdominal pain or cramps may also be present.