Colonoscopy Prep Tips: What Doctors Tell Their Friends

The physicians of the hit TV show The Doctors share what they want you to know about when to get a colonoscopy and how to prep for it.

doctor holding pad
Robyn Twomey for Reader’s Digest

FIRST OF ALL, get tested if you’re over age 50 or your doctor recommends it sooner. Colonoscopy is the most widely used screening test for colon cancer, which is among the most commonly diagnosed cancers. More than 50,000 Americans die from the disease every year. Colon cancer almost always begins as abnormal growths called polyps, which can be detected and removed during a colonoscopy, dramatically lowering your risk of developing the disease. But according to recent data, about 23 million U.S. adults have never been tested for colon cancer (even though two thirds of them have a regular doctor and insurance to pay for the test).

Two of us—Jim Sears, MD, and Travis Stork, MD—recently underwent colonoscopies on the air. So we grilled experts for advice on everything from choosing a doctor to gulping down the prep. Here’s what we want you to know about our experience.

“It’s no worse than a visit to the dentist”
“I’ve had three colonoscopies,” says Dr. Sears. “After each one, I wake up and think, You know, that wasn’t so bad. The worst part is just booking the appointment. Even the notoriously dreaded prep—drinking certain fluids or taking pills to flush out your system so your doctor can see every nook and cranny of your colon—feels kind of like a cleanse. It’s a day of not putting junk into your gut.”

“You feel fine? That’s the perfect time to be tested”
The logic among many patients goes, “I’m OK. Why should I have this procedure?” says Anish Sheth, MD, attending physician at the University Medical Center at Princeton in New Jersey. “But it’s most important [to have a colonoscopy] to find polyps before they turn cancerous.”

“Ask two key questions”
Not all doctors perform colonoscopies equally well. A less-than-thorough procedure may miss polyps or lead to complications like a tear in the bowel. Ask the doc about his “adenoma detection rate”—the percentage of patients in whom he finds precancerous polyps. This metric isn’t universally adopted, and many doctors may not know. (An ideal number is at least 15 percent for women and at least 25 percent for men.) If the doctor doesn’t know his rate, ask how many procedures he performs each day. You don’t necessarily want to choose someone who does just one, but a physician who does 20 may be prone to fatigue or be rushing through them.

“Split your prep time”
Taking half of the preparation the evening before and half the morning of the procedure is becoming more common, says Harry Sarles, MD, president of the American College of Gastroenterology. (With this type of prep, you typically need to take only one day off from work.) Research shows this method clears the bowels more effectively. This may mean it will be less likely that you’ll have to repeat the test because your colon was too clogged for your doctor to see it well.

“Constipated? Modify your diet for a few days before”
Most patients start a “clear liquids only” diet the morning of the day before a colonoscopy. But if you’re prone to constipation, your doctor may recommend that you follow a liquid diet for an extra day and eat a low-fiber diet for up to a week before. Since fiber is hard to digest, it takes a while to leave your colon.

“Request de-bloating”
As part of the test, air is pumped into the colon to expand its walls for a better view. Some docs use carbon dioxide instead because it exits the body more quickly and reduces bloating afterward. If your physician injects air, ask her to suction it out at the end of the procedure, which helps minimize gassiness and bloating.

Want to stay smart and healthy?

Get our weekly Health Reads newsletter

how we use your e-mail
We will use your email address to send you the newsletter each week, and we may also send you occasional special offers from Reader's Digest. For more information please read our privacy policy.

Some people like to travel by train because 
it combines the slowness of a car with the cramped public exposure of 
an airplane.

Dennis Miller

I think my pilot was a little inexperienced. We were sitting on the runway, and he said, “OK, folks, we’re gonna be taking off in a just few—whoa! Here we go.”

Kevin Nealon

“I can’t wait until your vacation is over.” 
—Everyone following you on Instagram


A man knocked on my door and asked for a donation toward the local swimming pool. So I gave him a glass of water.

Comedian Greg Davies

Funny Jokes

Just found the worst page in the entire dictionary. What I saw was disgraceful, disgusting, dishonest, and disingenuous.


Funny Jokes

Client: We need you to log in to the YouTube and make all our company videos viral.


Funny Jokes

My cat just walked up to the paper shredder and said, “Teach me 
everything you know.”


Funny Jokes

“Just because you can’t dance doesn’t mean you shouldn’t dance.” 

@yoyoha (Josh Hara)

Funny Jokes

My parents didn’t want to move to Florida, but they turned 60 and that’s the law.

—Jerry Seinfeld

Funny Jokes

Q: What do you call an Amish guy with his hand in a horse’s mouth?

A: A mechanic.

Fields marked with an * are required
Foods That Harm Foods That HealWant a Free eBook?
FOODS THAT HARM, FOODS THAT HEAL offers important information about the role diet plays in the struggle against heart disease, cancer, diabetes and other serious illnesses. Answer the question below to receive your FREE digital eBook.

Someone in my household experiences the following conditions:

Send me a link to download FOODS THAT HARM, FOODS THAT HEAL:
By clicking below, I agree to the Trusted Media Brands Privacy Policy