How long does a colonoscopy take? What should I expect? All of your questions, answered

Published: April 08, 2022

Author: Robert M. Dettmer, MD


Are you putting off your colonoscopy? Do you think you don’t need one because you’re healthy or younger than 50? No matter how healthy you are, you need a regular colonoscopy, starting at age 45, because it is the best way to screen for colorectal cancer or precancerous polyps.

I’ve had many patients in their 50s who, had they started having colonoscopies at age 45, could have avoided colorectal cancer. The fact is: Colonoscopy can save your life.

Colonoscopy detects and prevents at least 95% of colorectal cancers and increases the likelihood of curing them completely, especially if you have no or very early symptoms. Detected early enough, most colorectal cancers can be cured with simple surgery, even without chemotherapy. Detected later, however, colorectal cancers may require chemotherapy, multiple surgeries, and still not be curable.

Colonoscopy prep instructions

The good news is that everything about colonoscopy, from the prep to the actual procedure, is easier than ever. You no longer have to drink a gallon or more of a poor-tasting preparation to empty your colon. Now, you simply dissolve a tasteless, over-the-counter laxative into 64 ounces (1/2 a gallon) of your favorite clear liquid like, which you drink in 2-4 hours.

Clear liquids that you can drink:

  • Apple juice.
  • Black coffee.
  • Tea (no milk, no sugar).
  • Snapple drinks.
  • Gatorades.
  • Soda.
  • Water.
  • “Clear liquid” protein drinks.

Will I be up all night with colonoscopy prep?

You can start your “prep” day — the day before your colonoscopy — with a protein shake to keep up your energy for work. Then, at around 4 p.m., you can start drinking the actual preparation, which you should finish by 8 p.m. For the rest of the night, you’ll consume only clear liquids.

Related: Schedule a colonoscopy today

Usually within an hour or two of drinking the prep you can expect to have to use the bathroom. Sometimes you will need to go every 15 minutes, but then it will slow down. You will be able to get up from the toilet and then go back and use it again. It will not be a peaceful night, but it is manageable.

What to expect the day of your colonoscopy

The next day, you should arrive at the Tully Center an hour before your scheduled colonoscopy. You’ll sign in and store your clothes and other belongings in a personal locker. Then, you’ll meet the team of providers who will take care of you, including one of our board-certified anesthesiologists. All of Stamford Hospital’s anesthesiologists are board-certified, as are all of our doctors. Moreover, every aspect of the colonoscopy is government regulated to ensure safety and infection control. And by the way, our gastroenterologists have performed over a hundred thousand colonoscopies. I’ve done 25,000 myself.

Do they put you to sleep for a colonoscopy?

The anesthesiologist will administer a safe, gentle intravenous sedative that starts working within a minute or two. Before you know it, you’ll be sleeping.

Are colonoscopies safe?

Colonoscopy technology is tried and true. We use the latest equipment, including a thin, flexible, fiber optic colonoscope with a tiny, forward-viewing video camera that examines the inside of your colon for cancer and large precancerous polyps. Because these scopes are so thin and flexible, they bend easily to capture hard-to-reach areas of the colon.

The whole procedure takes no more than 15-20 minutes, and you won’t feel any of it. What’s more, you’ll wake up feeling wonderful. Most of my patients say that if they had known how easy a colonoscopy could be, they would have had it sooner.

Can you drive home after a colonoscopy?

Afterward, you’ll sit in the waiting area for 25 or 30 minutes, to give the anesthesia time to wear off. You may not drive yourself home, so remember to arrange for a ride in advance. Take it easy for the rest of the day and feel free to enjoy a full lunch and dinner.

Getting your colonoscopy results

As long as your results are negative, you can wait seven to 10 years before your next colonoscopy. Of course, no one wants to hear that they have colorectal cancer or precancerous polyps, but most people would rather find out sooner than later, so they can do something about it.

Colonoscopy at Stamford Health

Stamford Hospital’s Open Access system makes it easy to schedule a colonoscopy. Call (203) 276-7925, a nurse will make sure you’re a good candidate, and if you’re healthy enough and of the right age, then you can make an appointment at that time.

About the Author

Robert M. Dettmer, MD, is a gastroenterologist at Stamford Health.

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