What Is a Colonoscopy? From Prep to Recovery, Everything you Need to Know About the Procedure

Simpler prep and better screening make this (formerly) dreaded procedure a little easier to take.

Seventy-two percent of people say they'd avoid or delay getting a colonoscopy, according to a recent survey from the Merck Manuals. And while no one would argue that it's fun having a long, flexible tube inserted in your rectum to check for colon cancer or conditions like Crohn's disease or ulcerative colitis, the process has become simpler (especially the dreaded prep)—and the payoff is huge. "With most cancer-screening tests, you're trying to catch cancer in its early stages," says Charles Kahi, MD, a gastroenterologist and visiting professor of medicine at Indiana University School of Medicine in Indianapolis. "But with a colonoscopy, we can find precancerous polyps on the colon's inner lining and remove them during the procedure, so the test can actually prevent cancer from developing in the first place." A 2018 study by Dr. Kahi and his colleagues found that a colonoscopy reduced the risk of dying from colorectal cancer by 61 percent. Another advantage of a colonoscopy is it does not have to be repeated often, unlike most other screenings. If you get a clear result (no polyps), you may not need to repeat the exam for 10 years, depending on your medical and family history.

Think you're too young to worry? "We're seeing more people in their 30s and 40s, including younger women who are the picture of health, being diagnosed not just with [colon] cancer but advanced cancer," says Dr. Kahi. In fact, an estimated 49 people under 50 will be diagnosed every day this year with what's known as early-onset colorectal cancer. Here's what you need to know about the test, including why you might need one sooner than you think.

The Prep

The key to a successful colonoscopy is making sure your doctor can get a good look at every inch of your colon—and that means drinking a laxative solution and following certain dietary restrictions to get your insides squeaky-clean. The process has a bad rap, thanks in part to a foul-tasting liquid that is no longer used. The new drinks taste better, you don't have to drink as much, and you typically can drink the laxative in two sessions.

The prep process may start five to seven days before the procedure, so be sure to read the instructions ahead of time, says Natalie Cosgrove, MD, an assistant professor of medicine at the Washington University School of Medicine in St. Louis. One of the most common mistakes patients make is waiting until the last minute to read the prep instructions—at which point they may realize they've done something wrong and need to reschedule the test, she says.

Not every hospital or doctor recommends the exact same approach, so read your doctor's guidelines at least 10 days before your procedure—and follow them carefully. She'll most likely recommend that you stop taking over-the-counter fiber supplements and antidiarrheal medicines and supplements containing iron and vitamin E and stay away from high-fiber, slow-to-digest foods that might linger in the colon (like beans, seeds, multigrain bread, salad, vegetables, and fresh or dried fruit) several days to a week before the colonoscopy. She'll also recommend that you arrange for a friend or family member to pick you up after the procedure since you'll be having anesthesia or some type of sedation.

The day before the procedure, you can't eat solid food or consume alcohol, but you should drink enough clear liquid—like water, apple or white grape juice, broth, and coffee or tea (without milk or creamer)—to stay hydrated. And you'll probably start drinking the laxative at 6 p.m . It works by drawing water into your intestines, triggering numerous watery bowel movements. You're going to go a lot, so don't leave home. (The solution also contains electrolytes to prevent dehydration.) At some point, the stuff coming out is going to look clear, but don't stop drinking until the solution is all finished. "Patients think they're good to go when they're having clear diarrhea, but there may [still] be fecal matter left in your colon. You have to drink all of it unless your doctor tells you it's OK to stop," says Dr. Cosgrove. You should refrain from eating or drinking anything two hours before the procedure.

The Test

The whole process—checking in for the procedure, meeting with the anesthesiologist or doctor, and getting an IV placed—can last a couple of hours, but the procedure itself usually takes between 20 and 30 minutes, or sometimes longer, if you have polyps that need to be removed. During the procedure, your doctor uses a long, thin, flexible tube with a camera at the end to examine your colon. To remove most polyps, she may use a contractible wire loop to encircle them, severing them from the colon wall. Sometimes an electric current is used with the wire, depending on the size of the polyp. "Most people come out of anesthesia and don't even realize they've already had the procedure," says Dr. Kahi.

You may feel crampy afterward because the doctor pumps air into your colon to see the tissue more clearly. But serious complications are rare. Three of every 10,000 procedures result in a punctured colon, and eight of 10,000 tests that include polyp removal cause bleeding—problems that are almost always treated promptly and effectively, says Dr. Kahi. Because of the anesthesia, you'll be a little foggy for the rest of the day, so you shouldn't try to work or make any big decisions. You'll be hungry, too, but stick with easy-to-digest foods, like scrambled eggs, applesauce, or well-cooked vegetables. And drink plenty of water and broth or a sports drink to restore fluids and electrolytes.

New Thinking on Screening

In response to the early-onset trend, the American Cancer Society revised its guidelines in 2018 to say that everyone should get screened for colon cancer, through either a colonoscopy or a stool-based test, at age 45—five years earlier than previously recommended.

Not all doctors or medical organizations agree with the change. "We end up doing a lot of screening and [proportionately] don't find that many cancers," says Dr. Kahi. (The American Gastroenterological Association recommends that average-risk people start screening at age 50.) So talk to your doctor about what's best for you. She may want to begin screenings at 45 if you have any lifestyle-related risk factors associated with colon cancer—if you smoke or drink, for instance, or you're inactive or you eat a low-fiber, high-fat diet. She'll want to know if there is a family history of colon cancer or polyps. "If you have a first-degree relative who had colon cancer, start screening 10 years before the age that the relative was diagnosed or when you are 40, whichever is earlier," says Jennifer Maratt, MD, a gastroenterologist and assistant professor of medicine at Indiana University School of Medicine in Indianapolis. Because African Americans are at an increased risk for early-onset colon cancer, the American College of Gastroenterology suggests they begin screening at age 45.

And, at any age, if you have blood in your poop, ask your doctor for a test. "It used to be that we didn't worry greatly about bright red blood in a young person because it is often associated with hemorrhoids. Given the increasing incidence of colon cancer in younger people, however, we've become more vigilant, offering a colonoscopy to anyone who experiences bleeding, regardless of the color of the blood," says Dr. Kahi. Other possible colon cancer symptoms you should bring to your doctor's attention: persistent abdominal discomfort or pain, or changes in the consistency of your stool. But everyone with a colon has a risk of developing colon cancer, says Dr. Kahi: "Everyone should be screened at 50 at the latest."

Your sedation options

When Stephanie Bell, of Lexington, Kentucky, had a colonoscopy at 52, she chose an option few people even know exists: no sedation at all. "My fiancé had recently undergone the procedure without sedation and said it didn't hurt. I don't like to get IVs, anesthesia upsets my stomach, and I didn't want to be groggy afterward because I wanted to go to a party later that day. So I decided to try it too," she says. "My doctor talked to me throughout the procedure and warned me when I might feel a little discomfort because the scope had to make a turn in my colon. I felt pressure, like a Pap smear, but it wasn't painful. The embarrassment of having a tube inserted and seeing my colon on video was the worst part. But I would definitely do it again."

Dr. Kahi says the majority of his patients who go sedation-free are enthusiastic about the approach. Because you don't need an IV or medication, the procedure is less expensive than sedated colonoscopies. Another plus: You can drive yourself home afterward and do not have the same restrictions as someone who received sedation. But Dr. Kahi estimates that only a minority of patients choose it. "Most patients don't want to be aware [of what's happening] or feel any discomfort," he says. If you're one of them, here are the other two common approaches:

Moderate sedation (aka Conscious sedation or twilight sleep)

A doctor or nurse administers two medications, often midazolam, a benzodiazepine sedative that helps you relax, and fentanyl, an opioid to numb the pain. Because the drugs don't knock you out, you might be aware of what's happening during the procedure, but thanks to the amnesiac properties of midazolam, you're unlikely to remember it afterward. It takes time for the drugs to clear from your system, so you'll need to lie low for the rest of the day.

Deep sedation (aka monitored anesthesia care)

An anesthesiologist administers a drug, usually propofol, and monitors you during the procedure, which makes it more expensive. The drug doesn't numb pain, but you're sedated enough that you should be completely unaware of what's going on. (Deep sedation differs from general anesthesia, in which you're intubated with a breathing tube and a machine breathes for you; this is very rarely needed for a colonoscopy.) It causes less residual grogginess than moderate sedation, though you still need a ride home.

Do-it-yourself testing

If you don't have worrisome symptoms or lifestyle or genetic risk factors for colon cancer, there's a simpler test that doesn't involve days of prep or any downtime and is usually covered by health insurance. Known as Cologuard, all it requires is a small poop sample (you can get the testing kit from your doctor or online through a telemedicine provider), which you mail to a lab, so technicians can check for blood as well as changes in your cells' DNA associated with colon cancer or precancer. If the test is positive, you'll need a colonoscopy. If it doesn't find anything, you can wait three years before repeating it. But be aware that the test isn't as effective as a colonoscopy. A clinical study of nearly 10,000 people published in 2014 in The New England Journal of Medicine found that Cologuard detected 92 percent of the cancers that were found by colonoscopy and just 42 percent of suspicious polyps. So if you develop any symptoms—bleeding, stool changes, bloating, or unexplained weight loss—ask your doctor about having a colonoscopy, even if you've had a negative stool test, says Dr. Kahi.

This article originally appeared in the September 2020 issue of Health Magazine. Click here to subscribe today!

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