Information about Crohn's Disease Causes, Symptoms & Diagnosis
Crohn's disease is a chronic inflammatory disorder that primarily affects the small intestine, but it also can affect any segment of the digestive tract, including the colon, anus, mouth, and stomach. Crohn's disease can even affect the skin. About 500,000 people in the United States have Crohn's disease.
Causes of Crohn's disease
Despite extensive research, the cause of Crohn's disease is poorly understood. Three factors likely play a role. Genetics is one of them: Certain people inherit a susceptibility to the disease.
The second factor is environmental: A stimulus (perhaps a virus or bacterium) triggers the disease by causing the immune system to mount an attack against the digestive tract. Once the immune system gets turned on, it doesn't turn off properly. The third factor is race and ethnicity: Whites (particularly American Jews of European descent), followed by blacks, are more likely to get Crohn's than Hispanics and Asians.
Symptoms of Crohn's disease
Most often, Crohn's disease causes chronic inflammation of the small intestine. The inner lining of the small intestine becomes swollen and may develop erosions and ulcerations. These inflammatory changes usually result in abdominal pain and bloody diarrhea. The chronic inflammation can also lead to complications such as bowel perforation, peritonitis, abscesses, fistulas, and strictures.
Symptoms of Crohn's disease usually begin in the teen or young adult years. Once you have the disease you will have it for life. However, you will have symptom-free periods (remissions) that can last for years. A reappearance of symptoms is called a flare-up.
Diagnosis of Crohn's disease
The tests used to diagnose Crohn's disease depend on where your doctor thinks the inflammation is occurring. An upper GI series is the best test for Crohn's disease of the small intestine. Increasingly, capsule endoscopy is being used for diagnosis, although there is a risk that the capsule could get stuck in the digestive tract of people with disease who have strictures (which are common). Sometimes before a capsule endoscopy, doctors will prescribe a "patency capsule," which can detect the presence of strictures and (if it gets stuck) dissolve within 40 to 80 hours.
Colonoscopy or sigmoidoscopy may be used to detect Crohn's disease of the large intestine. If these tests aren't possible because of narrowing of the rectum or colon, a barium enema may be performed instead. If a fistula is suspected, the doctor may choose a more watery contrast dye called Gastrografin instead of barium. Genetic tests and blood tests are currently in development to detect Crohn's disease, but they are not yet sensitive or specific enough to be useful.