What Is Crohn's Disease (CD)?

Crohn's disease is an inflammatory condition that affects the digestive tract - including the mouth, esophagus, stomach, small and large intestine, and anus. It can affect any portion of the digestive tract, but is most common in the ileum - the lowest portion of the small intestine, where it connects with the large intestine.

The disease is characterized by active periods, known as flare-ups, followed by periods of remission, during which symptoms diminish or disappear altogether. Its cause is not known.

Crohn's disease may cause diarrhea, abdominal pain, and fever. Loss of appetite and weight loss also may accompany the disease. An individual's symptoms may range from mild to severe, but people with Crohn's disease are generally able to lead active and productive lives.

Treatments for Crohn's disease include a variety of medications, dietary adjustments, and, when necessary, surgery. In addition, patients are often encouraged to incorporate stress-reduction techniques into their daily activities.

Crohn's disease shares some symptoms with another inflammatory condition: ulcerative colitis. The two diseases are often grouped under the heading "inflammatory bowel disease." It is important to understand, however, that the two conditions are different.

• Ulcerative colitis affects only the mucosal membrane, or inner lining, of the GI wall and is limited to the colon.

• Crohn's disease affects the full thickness of the GI wall and can occur anywhere in the gastrointestinal tract, from the mouth to the anus.

A few individuals suffer a single bout of Crohn's disease, then go into remission and never experience another flare-up. Others suffer frequent bouts of active disease. For many people, flare-ups can be brought under control by a combination of medication and dietary changes. For some, a period of complete bowel rest (during which they are nourished with fluids delivered intravenously) is necessary.

More than half of all people who live with Crohn's disease will need to have surgery at some point to treat the disease. Surgical treatments include:

• Correction of a fistula (an inappropriate opening through the intestinal wall) or fissure (a deep crevice in the skin around the anus)

• Draining of an abscess (a pocket of infection on the bowel wall or outside the bowel wall near a portion of diseased bowel tissue)

• Opening of a stricture (narrowing) or obstruction of the bowel

• Removal (resection) of a segment of diseased tissue.

How Does CD Affect the Digestive System?

Crohn's disease is characterized by chronic inflammation in one or multiple areas of the gastrointestinal tract. Inflammation is the body's response to an abnormal physical, chemical, or biological stimulation, such as injury or infection. Complex reactions in the affected area produce heat, redness, swelling, and pain as the body works to heal an injury or destroy an infection.

In both Crohn's disease and ulcerative colitis, evidence suggests that either the body's inflammatory response is triggered when it shouldn't be, or it is triggered appropriately but fails to turn itself off after it has completed its job.