Preparing for a colonoscopy

Diet, tips, and instructions for a smooth colonoscopy prep

If you shudder at the thought of having a colonoscopy to check for hidden colon cancer, chances are it's the "prep" that's stoking your apprehension. But what's most off-putting is the purgative part: taking a powerful bowel-clearing substance and coping with the resulting diarrhea.

What's involved in colonoscopy prep?

Emptying the contents of the colon is a key requirement for a successful colonoscopy. If the bowel prep isn't up to par, polyps and lesions can be missed; the colonoscopy may take longer (increasing the risk of complications); or the whole process may need to be repeated or rescheduled, meaning another round of bowel prep.

Different medical centers recommend different ways to prepare the bowel for a colonoscopy. There are two parts: diet and drinking bowel-cleaning liquids. Here are some of the main strategies.

Colonoscopy prep diet

A few days before the colonoscopy procedure — Start eating a low-fiber diet: no whole grains, nuts, seeds, dried fruit, or raw fruits or vegetables.

The day before the colonoscopy procedure — Don't eat solid foods. Instead, consume only clear liquids like clear broth or bouillon, black coffee or tea, clear juice (apple, white grape), clear soft drinks or sports drinks, Jell-O, popsicles, etc.

The day of the colonoscopy procedure — As on the previous day, clear liquid foods only. Don't eat or drink anything two hours before the procedure.

Bowel prep for colonoscopy

The afternoon or evening before the colonoscopy, drink a liquid that will trigger bowel-clearing diarrhea. The exact colonoscopy prep instructions depend on the bowel prep your doctor prefers, the time of your colonoscopy, and any prior experience you've had with colon preps (if one didn't work before, you'll likely be prescribed a different one).