Polyps are benign growths involving the lining of the bowel (noncancerous tumors or neoplasms). They can occur in several locations in the gastrointestinal tract but are most common in the colon. They vary in size from less than a quarter of an inch to several inches in diameter. They look like small bumps growing from the lining of the bowel and protruding into the lumen (bowel cavity). They sometimes grow on a ďstalkĒ and look like mushrooms. Many patients have several polyps scattered in different parts of the colon.
Polyps are very common in adults, who have an increased chance of acquiring them as they age. While quite rare in 20-year-olds, itís estimated that the average 60-year-old without special risk factors for polyps has a 25 percent chance of having a polyp. We donít know what causes polyps. Some experts believe a high-fat, low-fiber diet can be a predisposition to polyp formation. There may be a genetic risk to develop polyps as well.
The biggest risk factor for developing polyps is being older than 50. A family history of colon polyps or colon cancer increases the risk of polyps. Also, patients with a personal history of polyps or colon cancer are at risk of developing new polyps. In addition, there are some rare polyp or cancer syndromes that run in families and increase the risk of polyps occurring at younger ages.
There are two common types: hyperplastic polyp and adenoma. The hyperplastic polyp is not at risk for cancer and, therefore, is not as significant. The adenoma, however, is thought to be the precursor (origin) for almost all colon cancers, although most adenomas never become cancers. A biopsy (or small piece of removed tissue) is the only way to differentiate between hyperplastic and adenomatous polyps. Although itís impossible to tell which adenomatous polyps will become cancers, larger polyps are more likely to become cancers and some of the largest ones (those larger than 1 inch) can already contain small areas of cancer. Because your doctor cannot be certain of the tissue type by the polypís appearance, doctors generally recommend removing all but the smallest polyps.
Most polyps cause no symptoms. Larger ones can cause blood in the stools, but even they are usually asymptomatic. Therefore, the best way to detect polyps is by screening individuals with no symptoms. Several other screening techniques are available: testing stool specimens for traces of blood, performing sigmoidoscopy to look into the lower third of the colon, or using a radiology test such as a barium enema. If one of these tests finds or suspects polyps, your doctor will generally recommend colonoscopy to remove them. Because colonoscopy is the most accurate way to detect polyps, many experts now recommend colonoscopy as a screening method so that any polyps found or suspected can be removed during the same procedure.
Most polyps found during colonoscopy can be completely removed during the procedure. Various removal techniques are available; most involve severing them with a wire loop and/or burning the polyp base with an electric current. This is called polyp resection. Because the bowelís lining isnít sensitive to cutting or burning, polyp resection doesnít cause discomfort. Resected polyps are then examined under a microscope to determine the tissue type and to detect any cancer.
Polyp removal (or polypectomy) during colonoscopy is a routine outpatient procedure. Possible complications, which are uncommon, include bleeding from the polypectomy site and perforation (a hole) of the colon. Bleeding from the polypectomy site can be immediate or delayed for several days; persistent bleeding can almost always be stopped by treatment during colonoscopy. Perforations usually require surgery to repair.
Your doctor will decide when your next colonoscopy is necessary. The timing depends on several factors, including the number and size of polyps removed, the polypsí tissue type and the quality of the colon cleansing for your previous procedure. The quality of cleansing affects your doctorís ability to see the surface of the colon.
If the polyps were small and the entire colon was well seen during your colonoscopy, doctors generally recommend a repeat colonoscopy in three years. If your repeat colonoscopy doesnít show any indication of polyps, you might not need another procedure for an additional five years. However, if the polyps were large and flat, your doctor might recommend an interval of only months before a repeat colonoscopy to assure complete polyp removal. Your doctor will discuss those options with you.