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Colonoscopy

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Colonoscopy

Definition:

A colonoscopy is an internal examination of the colon, using an instrument called a colonoscope. The colonoscope is a small camera attached to a flexible tube. Unlike sigmoidoscopy, which examines only the lower third of the colon, colonoscopy examines the entire length of the colon.

How the test is performed:

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You will lie on your left side with your knees drawn up toward the chest. After administration of a sedative and pain reliever, the colonoscope is inserted through the anus and gently advanced to the terminal small bowel.

Air will be inserted through the scope to provide a better view. Suction may be used to remove secretions.

Since better views are obtained during withdrawal than during insertion, a more careful examination is done during withdrawal of the scope. Tissue samples may be taken with tiny biopsy forceps inserted through the scope. Polyps may be removed with electrocautery snares, and photographs may be taken.

Specialized procedures, such as laser therapy, may also be performed.

How to prepare for the test:

Thorough cleansing of the bowel is mandatory. Instructions for doing this will be given by the provider. This will include using enemas, not eating solid foods 2 or 3 days before the test, and taking laxatives. You may be told to stop taking aspirin or other blood-thinning medications for several days before the test.

To avoid dehydration, drink plenty of clear liquids such as juices and broths. Unless otherwise instructed, continue taking any regularly-prescribed medication. Discontinue taking iron preparations a few weeks before the test, unless otherwise instructed by the health care provider. Iron residues produce a dark black stool, which inhibits the view.