Crohn’s Disease: The Basics

August 7th, 2013 by Eduardo Krajewski, MD, FACS, FASCRS

Crohn’s disease is one of the inflammatory bowel diseases. These diseases are also called “autoimmune” diseases. This means that the over-reaction of your body’s natural defense mechanisms causes problems. Crohn’s disease symptoms include stomach pain and diarrhea, and severe cases can even lead to malnutrition.

Nobody is sure what causes Crohn’s disease, and it usually occurs before age 30. Symptoms can appear gradually or suddenly. Smoking increases the risk of disease and worsens the severity of your symptoms. Crohn’s disease has been shown to run in families.

In this article we will discuss some of the basics about the disease. Treatment of Crohn’s disease will be presented in a separate article.

What Are the Symptoms of Crohn’s Disease?

Crohn’s disease can affect any part of the digestive tract from the mouth to the anus. However, the most common areas affected are the ileum (the last part of the small intestine) and the colon. The inflammation can be superficial and can cause scarring. This can lead to intestinal stricture which is the narrowing of the intestinal canal. Sometimes the problem extends completely through the intestinal wall, causing fistula formation. A fistula is an abnormal tract that connects the intestines to other organs like the bladder or vagina.

Some of the more common symptoms of Crohn’s disease are:

  • Diarrhea: In response to the inflammation your small intestine produces a lot of fluid causing diarrhea.
  • Abdominal pain: The thickened and scarred intestines can eventually develop areas of narrowing. This prevents the normal movement of stool, leading to pain and cramps. In more severe cases there can even be nausea, vomiting and intestinal obstruction.
  • Blood in stool: This bleeding can be visible or microscopic.
  • Ulcers: You can develop sores in any part of the digestive tract including the mouth and intestines. Sometimes these sores can even erode completely through the intestinal wall.
  • Weight loss and malnutrition: Symptoms can cause a loss of appetite. Also the disease can affect the absorption of nutrients from the intestines.
  • Other symptoms: Fever, tiredness, joint pain, eye inflammation, skin rashes, liver inflammation

What Are the Complications of Crohn’s Disease?

We have already mentioned some of the complications above. Bowel obstruction is one of the more severe complications and may even require surgery. Fistulas can abnormally connect your intestine with other sections of the digestive tract, which can interfere with the absorption of nutrients. Fistulas can also lead to collections of pus (also called abscesses) that might require surgical drainage. Fistulas can even drain out to the surface of the skin especially in the anal area. Fissures, or cracks in the skin around the anus, are also common in Crohn’s disease.

Crohn’s disease also can cause problems with the fingernails, anemia, arthritis, kidney stones, gallstones, bile duct inflammation and osteoporosis. Finally, Crohn’s disease increases your risk for developing colon cancer.

How is Crohn’s Disease Diagnosed?

The diagnosis is first suspected based on your symptoms like diarrhea and blood in the stool. Other tests that might be ordered to make the diagnosis are:

  • Colonoscopy: This is a thin tube with a tiny camera on the end which is inserted into the anus. This way your doctor can see the intestinal walls and look for signs of disease. A biopsy can also be obtained.
  • CT scan: This is a special type of x-ray that shows the details of your abdominal contents.
  • MRI scan: Similar to CT scanning, this test is especially useful in evaluating fistulas.
  • Capsule endoscopy: The small intestine is very long so it can be difficult to diagnose Crohn’s disease limited to this area. In this case your doctor may order this study where you swallow a small camera to take pictures of your small intestine.
  • Other tests: Blood tests, endoscopy, small bowel imaging, barium enema


Crohn’s disease is a serious autoimmune disease that can affect any part of the digestive tract. The resulting inflammation can lead to diarrhea, blood in the stool and a wide variety of other complications.

We will look at Crohn’s disease treatment options in another article.

Take a look around The H Doctor website. Here you will find the most current information about hemorrhoid treatment and other digestive health topics.

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