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What is colonoscopy?
Colonoscopy is a procedure that enables an examiner (usually a gastroenterologist) to evaluate the appearance of the inside of the colon (large bowel). This is accomplished by inserting a long flexible tube (the colonoscope) that is about the thickness of a finger into the anus and then advancing the colonoscope slowly into the rectum and through the colon. The tip of the colonoscope has a light and a video camera. The inner colon lining can be directly visualized in images transmitted from the camera to a television monitor. This traditional method of examination of the colon is called optical colonoscopy.
In preparation for colonoscopy, the day before the examination the colon is emptied using laxatives. Immediately prior to colonoscopy, an intravenous infusion (IV) is started, and the patient is placed on a monitor for continuously monitoring the rhythm of the heart, blood pressure, and the amount of oxygen in the blood. Medication usually is given by IV to make the patient sleepy and relaxed. If needed, the patient can receive additional doses of medication during the procedure. Colonoscopy often gives a feeling of pressure, cramping, and bloating; however, with the aid of the medication, colonoscopy generally is well tolerated and infrequently results in significant pain. The type of anesthesia caused by the intravenous medications is classified as conscious sedation and is safer than general anesthesia. With conscious sedation, patients are sleepy but still arousable, and able to breathe on their own. After the colonoscopy, patients are asked not to drive for the rest of the day if medications for conscious sedation were given.
Should there be polyps (benign growths that can lead to cancer) in the colon, the polyps, almost always can be removed through the colonoscope. Removal of these polyps is an important method of preventing colorectal cancer.