A Guide to Having a Colonoscopy

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Colorectal cancer is the second leading cause of cancer deaths in the U.S., according to the National Cancer Institute (NCI). However, the National Polyp Study showed that screening can reduce the number of deaths. Screening looks for signs of colon cancer in average-risk adults who have no symptoms. There are several types of colorectal cancer screening tests available, including the colonoscopy. Here’s a guide to having a colonoscopy.

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What is a colonoscopy?

A colonoscopy visually examines the walls of the colon for cancer and polyps, growths that may become cancer. “All colon cancer starts as polyps,” says Zuri Murrell, M.D., director of the Colorectal Cancer Center at Cedars-Sinai. While other screening tests find cancer, a colonoscopy is both a screening and prevention test. If your physician finds polyps, she can remove them during the colonoscopy, preventing them from eventually becoming a cancer, he says. There are several steps involved in preparing for a colonoscopy.

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Cleaning your bowel

You must thoroughly clean your bowel of fecal matter before undergoing a colonoscopy so your physician can clearly examine the walls of your colon. This is usually the hardest part for patients. There are two parts to this step: consuming a bowel cleansing preparation to evacuate your bowel and adhering to a clear liquid diet. Your doctor may also prescribe a laxative before bedtime. You’ll need to stay home and close to your bathroom during this process.

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Bowel cleansing formulas

Bowel cleansing formulas come in liquid, powder, and pill form. Some are only available by prescription; however, many are available over the counter at your pharmacy. Use the formula your physician prescribes. The most popular preps are a solution of polyethylene glycol (PEG). Drink plenty of fluids during this process to prevent dehydration, stopping about two hours before your colonoscopy.

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How to take the bowel prep formula

Your doctor may prescribe a split-dose bowel-cleansing regimen. This is generally the most highly recommended way to prepare for a colonoscopy. Take half the dose the afternoon or evening before your procedure and the rest about five hours before your colonoscopy. You may need to get up in the night to take the second dose. The timing of the second dose is important to prevent accumulations of mucous and secretions from the small intestine, which can interfere in your colonoscopy.

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Follow your physician’s instructions carefully

Pick up your bowel prep formula and instructions several days before your procedure and make sure you understand exactly what you’re supposed to do. Nearly one-quarter of adults undergoing colonoscopy have inadequate bowel preparation. You don’t want to have to repeat this process unnecessarily. Tell your doctor about any medications you take to make sure they won’t interfere in the bowel prep or colonoscopy.

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Consume only clean liquids

Stick with clear broth or fruit juice, tea, gelatin desserts, or sherbet during the bowel prep process. Don’t consume solid foods or anything with food colorings (especially red or purple), which may distort the results of your colonoscopy.

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The day of your procedure

When you arrive at the ambulatory surgical center or physician’s office a few hours before your procedure, you’ll sign a consent form. Now, your part of the procedure is done. The rest is up to the health care professionals. A nurse or technician will start an IV for fluids and medications. You’ll be sedated so you’re drowsy and comfortable. You won’t experience pain or discomfort and may not even remember the procedure.

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The colonoscopy procedure

Once sedated, you’ll lie on your side and your physician will insert a scope (about the size of your finger) with a small camera on the end into your anus. He’ll put air and water or saline in your colon to inflate it and make it easier to see clearly. Then he’ll advance the scope all the way to the beginning of your colon (the cecum). Finally, he’ll slowly withdraw the scope, examining all the nooks and crannies along the colon wall on a computer screen, looking for polyps or abnormalities.

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What happens if you have polyps?

If you have polyps, your physician will remove them during the colonoscopy and send them to a lab where a pathologist will look at them under microscope. Most polyps are just harmless bits of overgrowth of tissue from the colon wall. However, precancerous polyps (adenomas) may develop into a cancer over time. The pathologist will send a report back to your physician within a week or two. If your polyps were abnormal, your physician will tell you when you should have your next colonoscopy.

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After the colonoscopy

You’ll recover for up to an hour after the procedure. You may experience some bloating or cramping. This is normal and will pass. Arrange to have someone drive you home afterward, as you’ll be recovering from sedation.

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Risks of colonoscopy

A colonoscopy is generally a safe and well-tolerated procedure, says Dr. Murrell. The biggest risk factor is a perforation of the colon wall. Fortunately, this occurs in less than 1 percent of people undergoing screening colonoscopy, he says. Removing polyps or taking a biopsy of abnormal tissue may also cause some bleeding.

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Who should be screened?

The U.S. Preventive Services Task Force recommends adults at average risk begin colon cancer screening at age 50 and continue every 10 years until age 75. In 2018, the American Cancer Society lowered its recommended starting age to 45 for adults at average risk. If you have risk factors, your physician may recommend beginning earlier or undergoing more frequent screening. Physicians consider the colonoscopy the gold standard of colorectal cancer screening because removing polyps can prevent cancer.

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Final thoughts

Screening guidelines are just that — guidelines, says Dr. Murrell. You know your body. If you have symptoms, such as rectal bleeding, blood in your stool, or a change in your bowel habits, don’t wait until your next scheduled screening. See your physician promptly. Your symptoms are probably not due to cancer, but it’s best to find out for sure. If you do have cancer, finding it early increases the likelihood you can treat it successfully.