What happens during the endoscopy and colonoscopy procedures?


Before the procedure, the doctor will discuss with you why the procedure is being done, whether there are alternative procedures or tests, and what possible complications may result from the endoscopy.

Practices vary amongst doctors, but the patient may have the throat sprayed with a numbing solution and will probably be given sedating and pain alleviating medications through a vein. You will be relaxed after receiving this medication, usually midazolam (Versed) for sedation and fentanyl for pain relief, and you may even go to sleep. This form of sedation is called conscious sedation, and usually is administered by a nurse who monitors you during the entire procedure.

You also may be sedated using propofol (Diprivan) called “deep sedation,” which usually is administered by a nurse anesthetist or anesthesiologist who monitors your vital signs (blood pressure and pulse) as well as the amount of oxygen in your blood during the procedure.

After you are sedated while lying on your left side the flexible video endoscope, the thickness of a small finger, is passed through the mouth into the esophagus, stomach, and duodenum. This procedure will NOT interfere with your breathing. Most people experience only minimal discomfort during the test, and many sleep throughout the entire procedure using conscious sedation. Deep sedation ensures that you feel no discomfort during the entire procedure.

Afterwards, you’ll go to a rest area in the hospital or medical center to let the medication wear off. You must have someone drive you home as the sedation medication makes it unsafe to operate heavy machinery.


Prior to colonoscopy, intravenous fluids are started, and the patient is placed on a monitor for continuous monitoring of heart rhythm and blood pressure as well as oxygen in the blood. Medications (sedatives) usually are given through an intravenous line so the patient becomes sleepy and relaxed, and to reduce pain. If needed, the patient may receive additional doses of medication during the procedure. Colonoscopy often produces a feeling of pressure, cramping, and bloating in the abdomen; however, with the aid of medications, it is generally well-tolerated and infrequently causes severe pain.

Patients will lie on their left side or back as the colonoscope is slowly advanced. Once the tip of the colon (cecum) or the last portion of the small intestine (terminal ileum) is reached, the colonoscope is slowly withdrawn, and the lining of the colon is carefully examined. Colonoscopy usually takes 15 to 60 minutes. If the entire colon, for some reason, cannot be visualized, the physician may decide to try colonoscopy again at a later date with or without a different bowel preparation or may decide to order an X-ray or CT of the colon.

If an abnormal area needs to be better evaluated, a biopsy forceps can be passed through a channel in the colonoscope and a biopsy (a sample of the tissue) can be obtained. The biopsy is submitted to the pathology laboratory for examination under a microscope by a pathologist. If infection is suspected, a biopsy may be obtained for culturing of bacteria (and occasionally viruses or fungus) or examination under the microscope for parasites. If colonoscopy is performed because of bleeding, the site of bleeding can be identified, samples of tissue obtained (if necessary), and the bleeding controlled by several means. Should there be polyps, (benign growths that can become cancerous) they almost always can be removed through the colonoscope. Removal of these polyps is an important method of preventing colon and rectal cancer, although the great majority of polyps are benign and do not become cancerous. None of these additional procedures typically produces pain. Biopsies are taken for many reasons and do not necessarily mean that cancer is suspected.