How Do You Know When Your Bowel Prep is Complete?

Many rolls of empty toilet paper on the bathroom counter
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Cleaning out the entire colon prior to a colonoscopy is, quite honestly, what has some people running for the hills and avoiding this vital screening exam. Although it is not a pleasant olfactory experience, completing a bowel preparation is not painful. You want to be sure to stay close to home, however, as you will be using the toilet many, many times before the process is through. 

Be sure to tell your doctor if you have any heart, kidney or liver problems before scheduling the colonoscopy and bowel preparation. He or she may need to alter the type of bowel prep you use. 

Following your doctor's bowel prep instructions to the letter is very important. Although it may seem like one or more steps are redundant, such as using an enema after moving your bowels numerous times, there's a purpose for the entire process. Your doctor needs to get every bit of stool cleansed out, which will probably require more than two or three bowel movements. There is a reason why your bowels have to be squeaky clean: It makes it possible for your doctor see abnormal tissues that might be hidden by bowel contents. 

Each gastroenterologist follows the current cleansing guidelines based on evidence however, each doctor may order the prep a little differently.  What your friend's doctor told her to do for a bowel prep might not be the same instructions you receive. This is okay -- the doctor considers your health, what you may or may not be able to tolerate, and what has worked best in the past prior to instructing you on how to complete your prep.

Getting Started

The majority of bowel preparations begin with a drinkable solution or pills to be taken by mouth. You might start to see effects as soon as 30 minutes to an hour after your first glass of solution or your first pill. Your initial bowel movements will most likely be a combination of firm, semi firm, or loose brown stools.

 Continue to drink plenty of clear liquids and keep yourself hydrated, keeping in mind to avoid commercial drinks with purple or red dye as the dyes can interfere with your results. 

You might notice some uncomfortable, but not painful, side effects of the bowel prep. Stomach cramping and gas are most commonly complained of and are a completely normal side effect of forcing your bowels clean. Warm compresses and a small bit of exercise -- such as a walk around the house -- can help relieve some of the discomfort.

Nearing the Finish Line

When your bowel movements are composed of only brown liquids you are nearing the finish line. The color should progress to a cloudy liquid, and ultimately, to a yellowish clear liquid. If there is any cloudiness to your liquid stool your bowel prep is not complete. Also, finish the prep even if you have clear, liquid, yellowish stools prior to completing the entire prep. 

Why the Prep Matters

According to the American Journal of Gastroenterology, up to 25 percent of colonoscopies are cancelled due to a poor bowel prep. Deciding to cancel your procedure is not a decision made lightly, especially since your are most likely sedated and the doctor has already started the procedure prior to being able to determine if the colon is clean enough to continue.

If you didn't finish your prep or your bowel movements aren't reduced to clear liquids, contact your doctor so that he or she can help you reschedule your procedure.


American Society for Gastrointestinal Endoscopy. (n.d.). Understanding Bowel Preparation.

Johnson, D., et al. (September 2014). Optimizing Adequacy of Bowel Cleansing for Colonoscopy: Recommendations From the US Multi-Society Task Force on Colorectal Cancer. American Journal of Gastroenterology.

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