Colon Polyps

What Is It?

Colon polyps are growths of tissue that erupt from the mucous membrane on the interior of the large intestine. Some polyps take the form of bulbous protrusions on the end of a tubelike stalk, somewhat like a mushroom. Others appear as bumps that lie flat against the intestinal wall. There are several types of polyps. Most are benign, but one type, the adenomatous polyp, is associated with changes (called mutations) in the DNA of the lining of the colon. These mutations can progress into colon cancer. The larger the polyp, the greater the chance that it contains cancerous cells. For a polyp larger than 1 inch in diameter, there is a 10-percent likelihood it is cancerous. Flat polyps are more prone to becoming cancerous than mushroom-shaped ones.

No one knows exactly what causes these growths to occur, although some people are born with a genetic tendency to develop multiple polyps. Inherited conditions such as familial adenomatous polyposis and Gardner's syndrome can cause hundreds of polyps to grow in the colon and rectum. Without surgery to remove the affected section the intestine, it is almost certain that at least one of these polyps will turn into cancer by middle age. These two conditions are rare. Most adults are at risk of developing fewer polyps later in life, but are still at risk for complications.

Symptoms

Many times, people are not aware they have colon polyps because there are no symptoms. Larger growths can bleed, causing blood in the stool. Sometimes a person can experience fatigue and other symptoms of anemia from bleeding polyps. Occasionally, polyps can grow so large that they block the intestine or, rarely, cause diarrhea.

Diagnosis

Your doctor may use one or more of the following tests to confirm the existence of colon polyps:

• Digital rectal exam — The doctor inserts a gloved-finger into the rectum to check for unusual growths or formations. This can only detect polyps in the rectum, the lower few inches of the bowel.
• Fecal occult blood test — A sample of stool is examined for minute traces of blood, an indication of polyps.
• Sigmoidoscopy — A thin, lighted tube fitted with a video camera is inserted into the colon through the rectum allowing the doctor to examine the area for polyps. Small polyps can be removed through the scope.
• Colonoscopy — A longer version of the instrument used in sigmoidoscopy is used to visualize the entire length of the colon. This is the only test that examines all the areas where cancers may grow. Small polyps can be removed through the scope.