Overview: The Basics

A colonoscopy a visual examination of the entire large intestine (colon) using a lighted, flexible colonoscope. To be certain you are comfortable and relaxed, you will be sedated through an I.V. In fact, most patients are asleep during the entire process and remember little to nothing about it

What to Expect: During the Screening

When it’s time to start the screening, you will be asked to lie on your side. Once the sedation takes effect, the colonoscope is inserted through the rectum and moved gently around the bends of the colon. As the colonoscope makes its way through the colon, the physician can see the lining of the colon on a television screen. Typically, the physician looks all the way to the end of the large intestine and back for anything unusual. The entire scoping process typically takes between 15 and 30 minutes. When complete, your nurse will take you into a recovery area, where the sedation quickly wears off. Your physician will discuss the results of the test with you.

What can be found?

If polyps (small tissue growths) are found, your doctor can perform a biopsy immediately. The biopsy involves passing an instrument through the scope to remove the polyp, which is subsequently sent to a laboratory for analysis.

You should feel nothing when a biopsy or polyp is taken, and you should experience no recovery pain. While the overwhelming majority of polyps are harmless, your physician will have them tested and confirm your results with you, usually within 24-72 hours of the exam, depending on the day of the week of the procedure. Furthermore, since most cancer in the colon starts as a benign polyp, when these are removed, the possibility of them growing into cancer is removed as well.

What happens afterwards?

Once the nurse determines that enough of the sedation has worn off, you will be released, although you will not be able to drive. You may feel normal, but sedation has lingering and often subtle effects, which makes driving a treacherous activity. Please ensure that someone accompanies you to the procedure to drive you home after it has been completed.

How to Prepare

Thorough cleansing of the entire bowel is essential prior to the exam, and instructions for doing this will be given to you by your physician. These instructions can include a combination of the following: enema, restriction from eating solid foods a day or two before the test, and taking a powerful laxative in pill or liquid form. You may also be prohibited from taking aspirin or other blood thinners a few days before the exam as well.

To avoid dehydration, patients should drink clear, fat-free bouillon or broth, gelatin, strained fruit juice (no grape juice or any liquid with red color), and water. Unless otherwise instructed, continue taking any regularly-prescribed medication. If you are on iron preparations (to treat iron deficiency), your physician may also ask you to stop taking them a few weeks before the exam.

Lastly, your doctor will also want to know if you have heart or lung disease, or any other medical conditions that require special attention.


Colonoscopy Information

Stop Colon Cancer Now

National Cancer Institute: Colorectal Cancer Screening

Colorectal Cancer Screening: Questions and Answers

CDC: Colorectal Cancer Screening Saves Lives (PDF)

CDC: Colorectal Cancer Basic Facts on Screening (PDF)


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Cáncer del colon y del recto