7 Things You've Always Wondered About a Colonoscopy

It isn't so bad when you know what to expect.
Colonoscopy illustration
Visuals Unlimited, Inc./Carol & Mike Werner/Getty Images

A colonoscopy is a scary-sounding procedure (who wants a scope going up their most private orifice?!), but it’s one of the best detection tools doctors have for colorectal cancer and bowel diseases. Knowledge is power when it comes to any health procedure, and knowing what to anticipate will make things less worrisome. Here's what to expect before, during, and after a colonoscopy.

1. Um, how do I know if I need a colonoscopy?

For people with no personal or family history of colorectal cancer or inflammatory bowel disease like ulcerative colitis or Crohn's, colonoscopies don’t need to begin until the age of 50, according to the Centers for Disease Control and Prevention (CDC). After that first one, you'll need a test every 10 years.

But for those who meet any of the aforementioned qualifications, you may need to start much sooner and be screened more frequently. The American Cancer Society offers an excellent breakdown (with charts!) of when you should get a colonoscopy based on risk factors like a family history of cancer.

2. Do I have to follow a special diet before the colonoscopy?

The Colon Cancer Alliance recommends that you begin a low-fiber diet the week before your scheduled colonoscopy. In addition to sticking with low-fiber foods, they recommend avoiding fatty foods, fruits and raw vegetables with skins, whole grains, and anything with seeds or nuts, including popcorn. That's because in order for your doctor to successfully view your colon (aka your large intestine), it must be completely empty—and these foods can become caught in your colon for longer than typical waste. Their recommended meal plan includes things like eggs, white bread, turkey or chicken, Greek yogurt, spinach, and melon.

According to Rudolph Bedford, M.D., gastroenterologist at Providence Saint John’s Health Center in Santa Monica, California, preparation is the most important part. “If you don’t do a good job of emptying out your colon, your doctor won't be able to see it clearly,” Dr. Bedford tells SELF. “That can result in a missed polyp, a longer procedure, or even a need to repeat the procedure.”

3. OK, so what can I eat the day before the colonoscopy?

The day before your procedure, a clear liquid diet must be followed. According to the Mayo Clinic, this includes water, clear sodas, fat-free chicken or beef broth, and coffee or tea without added milk or cream. Some doctors have added restrictions or allowances (like hard candy), so make sure you follow their individual instructions. Dr. Bedford suggests checking the ingredients list on anything you eat the day before, and “avoiding any fluids that contain red, blue, or purple food coloring” as they can look like blood in your colon during the colonoscopy.

4. Is the prep really as bad as everyone says it is?

There is no sugar-coating this part: The final step of readying your digestive tract for a colonoscopy is to clear it completely, and this is...unpleasant. Each doctor has their own preferred method, but the end result will be the same: complete emptying of your colon. Some doctors prescribe a large volume of liquid laxative prep, while others recommend over-the-counter pill or powder laxatives. Regardless, you should do this part at home or somewhere you’re comfortable—you’ll be going to the bathroom frequently over the course of several hours, until what you pass is totally clear.

Some helpful prep tips from the Colon Cancer Alliance include chilling the prep solution, using a straw so the liquid goes to the back of your mouth and you avoid too much taste, and following the prep by sucking on a lemon slice or a piece of hard candy.

5. Well, now that all that is over, what happens the day of the procedure?

Some patients will have to finish the rest of their bowel prep that morning, while others will go directly to their appointment. Since you'll be given anesthesia, you'll need to arrange a ride home from the procedure ahead of time. On procedure day, you're not allowed anything by mouth (not even water or gum).

After you arrive at the hospital or surgical center, you’ll change into a gown and get blood taken. Then you’ll be taken to a private room for the colonoscopy. Sedation will be administered, so it’s likely you won’t remember any of the actual procedure (phew!). According to the Mayo Clinic, your doctor will insert a long, flexible tube called a colonoscope into your rectum. The scope has a small camera on the end, and images are projected onto a screen while your doctor does the procedure (you'll notice these screens in the room, before the sedation kicks in). He or she will also puff air into your colon so it expands for a better view. Biopsies (samples of tissue) may be taken, and if any polyps are found, your doctor will remove those as well.

6. So...about that extra air in my colon...

You'll be taken to a recovery area while the sedation wears off. As embarrassing as it might sound (no pun intended), you’ll need to get rid of the air that the doctor shot into your colon. Don’t try to hold it in, because that will only cause unnecessary cramping. Honestly, just take advantage of this one-time opportunity to pass gas without judgment. Once the sedation has mostly worn off, a nurse will check on you and send in the doctor.

“Once you feel better and are more awake,” Dr. Bedford says, “your doctor will provide you with a report of what was learned during the procedure.” This can include ulceration, inflammation, bleeding, scar tissue, polyps, or irregular tissue. Your doctor will also tell you if biopsies were taken and how long it will take to get a result. The Colon Cancer Alliance provides a great list of questions to ask your health provider after the procedure (you can read it here).

7. What should I do the rest of the day?

Once your ride has dropped you off safely at home, take it easy for the rest of the day. You’ll be hungry and thirsty, and unless your doctor has indicated otherwise, you’re free to eat a normal diet. You might still feel bloated or gassy, and the Mayo Clinic recommends taking a short walk to help pass the leftover air in your colon. You may also have a small amount of blood in your first bowel movement post-colonoscopy, especially if your doctor removed polyps or took biopsies. This is totally normal. But if you pass blood clots or get a fever, let your doctor know right away.

Not knowing what to expect during a colonoscopy can make it a whole lot scarier, so if you still have questions, ask your doctor. Being prepared for the procedure will help alleviate most of your worries, and they'll understand that you're nervous. But hey, your colon's health is far too important to neglect.

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