What is a Colonoscopy?
The term “colonoscopy” means looking inside the colon. It is a procedure performed commonly by a gastroenterologist, a well-trained subspecialist. The colon, or large bowel, is the last portion of your digestive or GI tract. It starts at the cecum, which attaches to the end of the small intestine, and it ends at the rectum and anus. The colon is a hollow tube about five feet long, and its main function is to store unabsorbed food products prior to their elimination. The main instrument that is used to look inside the colon is the colonoscope, which is a long, thin, flexible tube with a tiny video camera and a light on the end. By adjusting the various controls on the colonoscope, the gastroenterologist can carefully guide the instrument in any direction to look at the inside of the colon. The quality picture from the colonoscope is shown on a TV monitor and gives a clear detailed view. Colonoscopy is more precise than an x-ray. This procedure also allows other instruments to be passed through the colonoscope. These may be used, for example, to painlessly remove a suspicious-looking growth or to take a biopsy – a small piece for further analysis. In this way, colonoscopy may help to avoid surgery or better define what type of surgery may need to be done. A shorter version of the colonoscope is called a sigmoidoscope, an instrument used to screen the lower part of the large bowel only. The colonoscope, however, is long enough to inspect all of the large bowel and even part of the small intestine.
Why is it done?
Colonoscopy is a safe and effective way to evaluate problems such as blood loss, pain, and changes in bowel habits, such as chronic diarrhea or abnormalities that may have first been detected by other tests. Colonoscopy can also identify and treat active bleeding from the bowel. Colonoscopy is also an important way to check for colon cancer and to treat colon polyps – abnormal growths on the inside lining of the intestine. Polyps vary in size and shape and, while most are not cancerous, some may turn into cancer. However, it is not possible to tell just by looking at a polyp if it is malignant or potentially malignant. This is why colonoscopy is often used to remove polyps, a technique called a polypectomy. Colonoscopy is also used as a screening and surveillance test for patients with a family history of colonic cancer.