Colonoscopy

Colonoscopy is a medical procedure which uses a long, flexible scope to visualize the interior of the large intestine (the colon). An experienced gastroenterologist (physician who specializes in diseases of the digestive tract) can identify a number of abnormalities in the rectum and colon with this procedure. It also allows biopsy and removal of small amounts of tissues from within the intestine to aid in diagnosis and to treat the abnormalities.

This study is used to screen for and diagnose a number of different diseases of the rectum and large intesting, including inflammatory bowel disease, colon polyps and colon cancer. It is most commonly used in colon cancer screening and colon cancer prevention. It may be used as screening in someone without any symptoms or other findings but may also be used to more fully work up other concerning findings, such as blood in the stool or changes in bowel habits.

There is some disagreement about the recommended frequency and type of screening for colon cancer. The American College of Gastroenterology suggests that screening be performed every 5 years after age 50 for the early detection of colon cancer and colon polyps which may lead to cancer. Removal of these polyps can help decrease the risk for future development of colon cancer. Other forms of colon cancer screening are used, such as CT imaging, testing the stool for blood and sigmoidoscopy. However, colonoscopy has the advantages that it allows direct visual inspection of the entire rectum and large intestine and also allows the removal of suspicious lesions or polyps through the same procedure. The type and frequency of screening recommended may vary depending on other factors such as family history, age and other factors. Each individual should discuss their need for screening with their own physician.

How is it performed? Prior to the study, the bowel must be emptied and cleansed to allow clear visualization of the walls of the colon. This is generally done by drinking various forms of colon cleansing solutions which clean out the colon. Most patients are lightly sedated for the procedure and the gastroenterologist inserts the flexible scope into the rectum through the anus. The physician visualizes the interior of the colon on a screen. The scope is slowly maneuvered through the length of the large intestine, examining the walls for any abnormalities. If abnormalities are found, they can be biopsied or removed with a small grasping tool passed through the scope. This tissue can then be sent to a pathologist for diagnosis.

While complications, such as bleeding, tearing or perforation, can occur, they are generally very rare, other than minor bleeding. On the other hand, regular screening may dramatically decrease ones risk of dying of colon cancer. While it can miss very small lesions, colonoscopy is probably the most sensitive study to detect the early stages of colon cancer.

Another similar procedure is sigmoidoscopy which uses a shorter scope to visualize just the end portion of the colon and rectum. It is faster and easier to perform but does not visualize the entire colon and therefore may miss concerning lesions.