Colonoscopy Prep 101

Colorectal cancer is one of the most common and deadliest cancers in the United States. It is also one of the most preventable and treatable cancer types, largely thanks to colonoscopies. Despite their health benefits, only around 60% of people are up to date on their colon cancer screening test. Among people aged 45 to 50, who were recently added to the group recommended to begin colorectal screenings in 2021, that rate drops to just 20%. 

Many people who delay or avoid a colonoscopy are worried about pain or discomfort, usually related to the preparation process. To help make the process easier and less stressful, we spoke with Sheila Rustgi, MD, a gastroenterologist at Columbia University Irving Medical Center and a member of the Herbert Irving Comprehensive Cancer Center, to share expert tips on how to prepare for a colonoscopy and make 'prep night' as smooth as possible. 

Why is colonoscopy prep important? 

A colonoscopy is a vital screening tool that helps find changes in the colon, such as polyps or signs of various gastrointestinal diseases, including colorectal cancer. During the 30 to 60-minute procedure, a long flexible tube with a camera on the end is inserted into the rectum to allow doctors to examine the colon. Patients are usually under sedation, so they do not feel or remember anything about the procedure. 

For a clear and accurate view, the colon must be completely empty and clean.  This is why bowel prep —the process of clearing out the colon using a prescribed laxative—is essential. If colonoscopy prep isn’t done properly, the procedure may need to be rescheduled. 

When should you start preparing for a colonoscopy? 

Adjusting your diet a few days before prep night can help the process go smoother. Eat smaller portions of foods low in fiber, such as eggs, rice, salmon, chicken, steamed vegetables, and white pasta. Try to avoid things like nuts and seeds, red meat, popcorn and raw vegetables, and other high-fiber foods. 

What happens on prep night? 

The night before your procedure, you’ll drink a liquid laxative solution to clear out your colon. Most patients need to drink half the solution in the evening and the other half six hours before your appointment. Some doctors may recommend a mix of the laxative and a sports drink. Frequent, watery bowel movements will begin soon after drinking the solution.  

Common prep challenges and solutions: 

• Taste Concerns? Serve the prep solution cold, sip through a straw, or chase with a flavored drink.
• Nausea or cramping? Drinking slowly and staying hydrated with clear fluids may help. Your doctor may recommend medication if symptoms persist.  

Can you eat during prep night? 

No! Once you start the prep, you must stick to a liquid only diet. You can add your prep solution to any clear liquid, just be sure to avoid liquids with orange, red, or purple dyes since they could look like traces of blood during the colonoscopy. Other liquids that are ok during prep night are low-sodium broths, gelatin, clear fruit juices, black coffee and teas (without creamers), sparkling water, and Gatorade or sports drinks.  Some patients may find that drinking electrolytes helps them stay hydrated. Liquids that are NOT clear, like milk or orange juice, should be avoided. 

How can you stay comfortable during colonoscopy prep? 

You will be spending a lot of time in the bathroom, so make it as comfortable as possible. Investing in soft, strong toilet paper is important to prevent chafing. Wet wipes, creams and vaseline can help soothe any irritation. Try to apply these before the laxative kicks in.  

What happens after a colonoscopy? 

You may feel a bit groggy as you wake up from the procedure. You will need someone to escort you home after the procedure. You will be free to return home and rest. Once you feel up for it, you should be able to resume your normal activities. You may be hungry and while there are no specific dietary restrictions after a colonoscopy, we recommend easing back into eating and starting with light easy-to-digest foods like soup, pasta or lean proteins. It may take a few days for your bowel movements to feel normal, so you should avoid heavy, spicy, or greasy foods.  

It’s important to try and remember that colonoscopy prep is one night of discomfort for a decade of reassurance. If no polyps or irregularities are found, you likely won't need another one for ten years.