Crohn's Disease: Key Q&A

What is Crohn's disease?

Crohn's disease is an inflammatory bowel disease that causes chronic inflammation and ulceration within the digestive tract. Ulcers in the intestinal lining and inflamed tissue may swell, redden and bleed, often leading to bloody diarrhea, abdominal pain and cramping. This irritation can run deep -- into all layers of your gastrointestinal lining. Inflammation may be confined to one location or it may occur in patches, with normal tissue located between inflamed areas.

How common is Crohn's disease?

About 500,000 Americans have Crohn's disease, according to the Crohn's & Colitis Foundation of America. Another 500,000 have ulcerative colitis, the other major type of inflammatory bowel disease. Crohn's disease most often occurs in young people between the ages of 15 and 35, but may also occur in older or younger populations.

What causes it?

The cause of Crohn's disease is unknown, but it appears to involve dysfunction of the immune system. Protective cells normally present in the gastrointestinal lining are triggered to attack when bacteria and viruses pass through the digestive tract. In people with Crohn's disease, this attack continues, even when harmful substances are no longer present, leading to chronic inflammation and irritation. It is not clear whether this immune dysfunction is a cause or result of Crohn's disease.

How does Crohn's disease affect people?

People with Crohn's disease have a wide variety of symptoms. This is because the disease can affect different parts of the digestive tract and in different ways, such as with swelling, edema or the development of abnormal passages called fistulae. Crohn's disease can cause deep tissue irritation and can lead to serious medical complications, such as obstruction or perforation of the intestines, which can require surgery. People with Crohn's disease may experience alternating periods of symptom activity and relief throughout their lives.

Are there different types of Crohn's disease?

Yes. Crohn's disease may be classified into various types, depending on the location of symptoms. Crohn's disease most commonly affects the small intestine, which is made up of the duodenum, jejunum and ileum, and large intestine, which includes the cecum, colon and rectum. The various types of Crohn's disease include:

Ileocolitis. The most common form of Crohn's disease, with symptoms occurring in both the small intestine's ileum and the first part of the large intestine, the cecum. Symptoms include diarrhea, significant weight loss, and cramping or pain in the lower right or middle of the abdomen.
Ileitis. When inflammation occurs in the ileum. The symptoms are similar to those of ileocolitis, although fistulas and abscesses may also develop.
Gastroduodenal Crohn's disease. Affects the stomach and small intestine's duodenum. Symptoms include loss of appetite, nausea, vomiting and weight loss. Vomiting may indicate an intestinal obstruction.
Jejunoileitis. Inflammation of the jejunum, the largest part of the small intestine. Symptoms include diarrhea, abdominal pain and cramping. Malnutrition may occur, due to malabsorption by the jejunum, where most absorption of nutrients occurs. Fistulas (abnormal connections) may also develop.
Granulomatous colitis. Inflamed tissues called granulomas occur in the colon. Granulomas are a feature of Crohn's disease; they do not appear in ulcerative colitis, the other major form of inflammatory bowel disease. Symptoms include diarrhea, blood in the stool, skin lesions and joint pains. Abscesses, fistulas and ulcers may develop around the anus. Granulomatous enteritis, which is also called regional enteritis, features similar symptoms but affects the small intestine only.

What is the difference between Crohn's disease and ulcerative colitis?

Crohn's disease is distinguished from ulcerative colitis in a number of ways. Crohn's disease can affect areas within the entire digestive tract, whereas ulcerative colitis symptoms appear only in the large intestine. Inflammation is continuous with ulcerative colitis but may appear in patches with Crohn's disease. In addition, ulcerative colitis does not cause deep-tissue irritation; its inflammation affects just the inner lining of the intestinal wall. Thus, ulcerative colitis is less likely to lead to intestinal obstructions or perforations that can require surgical treatment, as can happen with Crohn's disease.

How is Crohn's disease treated?

Although there is no cure for Crohn's disease, various medical and surgical treatment options exist. Medications are available to help reduce or eliminate the ulcers and inflammation caused by the condition, as well as the symptoms of Crohn's disease, such as diarrhea and abdominal pain.

Surgery may be necessary when severe inflammation and ulcers cause parts of the intestines to narrow, food products are diverted from their normal digestive pathway or when food gets stuck in the intestines. Even after surgery, however, Crohn's disease often reappears elsewhere in the digestive tract. Most patients require surgery at some point.