How Should I Prepare for My Colonoscopy?

If you have decided to undergo a colonoscopy, congratulations! You have made an important decision to change the trajectory of your health and prevent a deadly cancer from affecting your life and those around you. In preparation for your colonoscopy, there are some changes to you diet and medications that should be held prior undergoing a colonoscopy. You doctor will provide both written and verbal instructions of the things change. A week before your colonoscopy, make sure read the instructions at least twice. (1) Our blog and podcast are not a substitution for speaking with your doctor and following their instructions.

To prepare for your colonoscopy you would need to “clean your bowels.” This is called a bowel preparation. A good bowel preparation allows the doctor to see all the surfaces of your colon. In this way, you doctor can find and remove polys or other masses with better accuracy. Unfortunately, about 25% of those undergoing colonoscopy will have a poor bowel preparation and, as result, polys or other masses may be missed. (2) Therefore, in order to get the most out of your colonoscopy, it is important that you follow you doctor’s instructions completely for your bowel preparation.

The bowel preparation is done by drinking bottles of fluid that contain a medication called polyethene glycol. This is the same medication found in a constipation medication with the trade name MiraLAX. This medication is safe and effective. It works by drawing water into your colon to help flush out the stool. This solution may also contain some electrolytes. Do not replace this solution for any over the counter product or other colon cleaning agents. It is important that you follow your doctor’s instructions and use the right colon cleanse solution. Also, it is important that you remain well hydrated as you clean your bowel in preparation for colonoscopy as you will lose some of your body’s water content with diarrhea. As you make multiple trips to the bathroom, there is an inconvenience of diarrhea, but it is worth it. There are two ways to take this bottle of colon cleansing solution. You can drink the complete solution at once a day before your colonoscopy. Otherwise, you can drink half the solution the night before and the other half the morning of your colonoscopy. Splitting the dose in 2 days is generally better tolerated. The timing of drinking this solution is important. Therefore, speak with your doctor about the times you should drink this solution if you decide to split the bottle in half over 2 days.

There also needs to be changes to your diet and the medications before getting your colonoscopy. At least a day before your colonoscopy, you should only drink water, coffee, tea or fruit juice. This is called a clear liquid diet. There should be care to avoid red liquids as this can be mistaken for blood during your colonoscopy.  You should have no liquids for about 4 – 8 hours before your colonoscopy. You may take certain medications with sips of water. (1) Also, your doctor may ask you to hold certain medications that can affect you bleeding, such as aspirin, clopidogrel, coumadin or other blood thinners. You should also be careful with certain diabetes medications when you are fasting as well. Make you to speak with you doctor and review all your medications and determine which you are able to take, or hold, in the days or weeks before your colonoscopy.

Finally, during your colonoscopy you may receive sedation or “twilight.” With sedation, you may be in or out or consciousness during the procedure.  Many times, you may not remember the procedure at all. Since you will receive sedation, you generally will not feel any pain or discomfort during the colonoscopy. Care is taken to make sure these medications will have minimal to no effect on your breathing. Therefore, in most cases someone undergoing a colonoscopy will not need a breathing tube. You will need to be monitored after your colonoscopy to make sure your vital signs are stable and regain consciousness. Yet, you should not drive yourself home after the procedure and will need to be accompanied by a family member or friend.

There are some complications that can occur with colonoscopy, but the risk is very low. The most common complication with colonoscopy is bleeding. Bleeding tends to occur when a polyp is removed and is generally minimal. Bleeding after colonoscopy occurs in about 1 – 2% of the cases. It is also possible for a small hole to develop in your colon during or after the procedure. This a called a bowel perforation. The risk of bowel perforation is also very low and occurs at a rate of about 0.01 – 0.1% in those who have a colonoscopy to screen for colon cancer. (1) Despite these potential complications, colonoscopy is considered safe and effective.

Although there is some planning and inconvenience involved in getting a colonoscopy, it is generally agreed upon in the medical community that a colonoscopy is the preferred method of screening for colon cancer given its above to diagnose and treatment precancerous polyps. If the FIT or DNA stool tests are positive, a colonoscopy will be needed. Therefore, a colonoscopy is a good starting point for those who can tolerate the inconvenience of bowel preparation, dietary and medication restrictions and sedation in order to get the gold standard in testing. A colonoscopy not only catches cancer, but also find pre-cancerous polyps, adenomas and other diseases of the colon. If your coloscopy is normal, you may not require another procedure in the next 5-10 years. Flushing out your colon before the procedure is very important and care should be taken to ensure you drink your bottles of polyethylene glycol in completion to your doctors’ instructions. Make sure to stick to a clear liquid diet before your colonoscopy. Speak with your doctor about which medications, especially blood thinners and diabetic medications, should be held before undergoing your colonoscopy.  

REFERENCES
1. Lee L &Saltzman JR. Overview of colonoscopy in adults. In: UpToDate, Howell AD & Grover S. (Eds), UpToDate, Waltham, MA. (Accessed on July 24, 2021.)
2. Ness RM, Manam R, Hoen H, Chalasani N. Predictors of inadequate bowel preparation for colonoscopy. Am J Gastroenterol. 2001 Jun;96(6):1797-802.