Q: What are the most common types of endoscopies?

A: An endoscopy uses a lighted scope to inspect the lining of the upper and lower intestinal tracts. It is used to determine the causes of symptoms, and to treat the problem. It also can find and remove precancerous lesions.

One type, colonoscopy, involves a bowel preparation followed by the insertion of a lighted flexible tube into the colon while the patient is sedated. The entire colon is examined for polyps (precursors to cancer), tumors, inflammation, or sources of bleeding. Tissue samples also can be collected, and abnormal growths can be removed.

Flexible sigmoidoscopy examines only the lower portion of the large intestine (rectum and sigmoid colon). It can be done without sedation, and is used to assess lower gastrointestinal bleeding and to detect polyps.

Computed tomography (CT scan colonography) is used to detect polyps and cancer. A bowel preparation is needed, but not sedation. It is noninvasive, but if a polyp is found, a colonoscopy is often needed to remove it.

Screening for colonic polyps should begin at age 50 in patients with no symptoms and with no family history of colon cancer. Colonoscopy is recommended every 10 years in average-risk patients and every five years in those with a family history, and more often if polyps are found.