What is a colonoscopy?

A colonoscopy is an outpatient procedure that is done to examine the inside of your large intestine (colon and rectum). The examination uses an instrument called a colonoscope (sometimes called a scope). This flexible instrument is very long and includes a camera and the ability to remove tissue (you won't feel the tissue being removed). A colonoscopy is commonly used to evaluate gastrointestinal symptoms, such as bleeding, abdominal pain or changes in bowel habits (how often you poop, how easily you poop, and the color and consistency of your poop).

Colonoscopy can be used to detect ulcerative colitits, polyps, cancer, diverticulosis and Crohn's disease.

A colonoscopy can be used to detect many different types of conditions.

Some people may avoid the procedure due to embarrassment or a reluctance to go through the preparation. There are many bowel preparations available, and they come in different sizes and tastes. Also, the colonoscopy team respects your privacy during the entire procedure. Colonoscopies are done to check for colorectal polyps or cancer. Removing polyps early means they can’t turn into cancer.

The medical community recommends that anyone who does not have risk factors for colorectal cancer should begin regular colonoscopy screenings starting at age 45. The frequency of your colonoscopies will vary depending on the findings. You may need to have a colonoscopy at a younger age if you have a higher risk of colon cancer. Risk factors may include:

  • Having familial polyposis syndrome (a condition that runs in your family and is linked to an increased risk of forming polyps).
  • Having a genetic condition associated with colon cancer.
  • Having inflammatory bowel disease, such as Crohn’s disease and ulcerative colitis.
  • Having first-degree relatives with colon cancer (that is, your mother or father, brother or sister, or child).
  • Having multiple relatives with colon cancer.

Test Details

What should I know or tell my doctor before a colonoscopy?

Be sure to tell your doctor exactly what medicines you take on a daily basis. This includes prescription and over-the-counter products like supplements. Your doctor can tell you which medications to avoid and what changes might be necessary. It is possible that you might have to reschedule your medications if you have diabetes or need blood thinners.

You will need a driver. Most facilities will not let you check in or perform the exam at all if you do not bring a responsible driver with you.

To have a successful colonoscopy, you will have to do your part. This means following all the instructions about what to eat and drink in the days before the procedure. It also means making sure that your colon is empty so your doctor can see clearly when the scope is inside the colon. This involves what is known as ‘bowel preparation.’

Bowel preparation. Colonoscopy prep. Cleaning out your colon. What does this mean?

Your healthcare team will give you plenty of time to prepare. You will get instructions at least two weeks before the procedure. It is important to read and follow all of the instructions given to you. If your bowel is not empty, your colonoscopy will not be successful and may have to be repeated. The cleaner your colon, the better chance your provider will have at finding all of your polyps and cancer, which sometimes can be small or hidden.

What can you eat and drink in the days before a colonoscopy?

Some providers may ask you to avoid corn, nuts, seeds and popcorn for at least three days before the procedure. Others might suggest a low-fiber diet for two days before the colonoscopy. The day before the procedure you will not be able to eat solid food or drink alcohol

You will be able to drink clear liquids, including water, black coffee, tea, ginger ale, apple juice, white grape juice and clear broths. You can have JELL-O® and Popsicles®, but only those that are not red, blue or purple. Drinking extra fluid will help you not become severely dehydrated.

You should not drink or eat anything at all for at least four hours before the colonoscopy. Be sure to drink plenty of fluids the day before while you are doing your bowel prep. If you are having your colonoscopy with general anesthesia, then you cannot drink anything after midnight on the night preceding your test.

What exactly does bowel preparation mean?

There are a few different kinds of bowel preparations for colonoscopy, almost all of them liquid. Your doctor will tell you what kind is best for you based on your medical history and their particular preference. Some of these products are prescription-only, while others are available over-the-counter. They all have the same goal — to get rid of everything in your colon by causing watery diarrhea.

The time of day or night that you will have to start drinking the solution will depend on when your procedure is scheduled. You will be asked to consume the entire amount of liquid within a specific time period. There is also something called “split-dosing.” In split dosing, you will be asked to drink half of the bowel preparation the night before and then stop. You will get up in the morning and do the other half of the dose in the morning, finishing up at least four hours before the procedure itself. In general, split dosing results in cleaner bowel preparations. If you are having a colonoscopy with conscious sedation or twilight, and you have not been given split dosing instructions, ask your provider if you can do the split dosing.

What can you do to make a colonoscopy preparation easier?

There are things that might help you to drink the solution more easily. These include using a straw to drink the liquid and cooling the solution in the refrigerator before drinking it. You can add lemon drops or chew ginger candy. You will need to stay close to the bathroom during bowel preparation period. A split-dose might make the preparation easier. You will know you have done a good job when your diarrhea looks clear and yellowish, like urine.

You may experience skin irritation around the anus due to the passage of liquid stools. To prevent and treat skin irritation, you should:

  • Apply Vaseline® or Desitin® ointment to the skin around the anus before drinking the bowel preparation medications. These products can be purchased at any drug store.
  • Wipe the skin after each bowel movement with disposable wet wipes instead of toilet paper. These are found in the toilet paper area of the store.
  • Sit in a bathtub filled with warm water for 10 to 15 minutes after you finish passing a stool. After soaking, blot the skin dry with a soft cloth. Then apply Vaseline or Desitin ointment to the anal area, and place a cotton ball just outside your anus to absorb leaking fluid.

What happens on the day of a colonoscopy?

Take a shower in the morning if you like, but do not use lotions, perfumes, or deodorants. Leave your jewelry, other valuables and contact lenses at home.

During the procedure itself:

  • You are asked to wear a hospital gown and an IV will be started.
  • The procedure can be done with conscious sedation, often referred to as “twilight,” or deeper sedation referred to as “general anesthesia.” You are given a pain reliever and a sedative intravenously (in your vein). You will feel relaxed and somewhat drowsy. This step means that the colonoscopy will not hurt.
  • You will lie on your left side, with your knees drawn up towards your chest.
  • A small amount of air is used to expand the colon so the doctor can see the colon walls.
  • You may feel mild cramping during the procedure. Cramping can be reduced by taking slow, deep breaths.
  • The colonoscope is slowly withdrawn while the lining of your bowel is carefully examined.
  • The procedure lasts about 30 minutes. It takes about 12 minutes to move the scope five or six feet and another 12 minutes to take it out. If there are polyps to remove, the procedure will take longer.

What happens after a colonoscopy?

  • You will stay in a recovery room for observation until you are ready for discharge. The amount of time that you are in recovery depends on whether or not you were sedated and what type of pain management medication you received.
  • You may feel some cramping or a sensation of having gas, but this should pass quickly.
  • Your responsible family member or friend will drive you home.
  • Avoid alcohol, driving and operating machinery for 24 hours following the procedure.
  • Unless otherwise instructed, you may immediately return to your normal diet. It’s recommended that you wait until the day after your procedure to resume normal activities.
  • The doctor performing your colonoscopy will tell you when it’s safe to resume taking your blood thinners or any other medications you might have stopped.
  • If polyps were removed or a biopsy was done, you may notice light rectal bleeding for one to two days after the procedure.

NOTE: If you have a large amount of rectal bleeding, high or persistent fevers, or severe abdominal pain within the next two weeks, go to your local emergency room and call the doctor who performed your exam.

How long will it be before my next bowel movement?

It might take a few days before you have a bowel movement because your colon is empty. It also depends on how much roughage (fibrous foods) you eat.

Care at Cleveland Clinic

Results and Follow-Up

When will I know the results of the colonoscopy?

Usually, your doctor will speak with you after the procedure to explain what was done. The doctor will tell you if you did have polyps and if any tissue was removed. They will also go over when you are able to start taking your medications again if you had to stop taking something before the colonoscopy.

Also, usually you will get a formal report either mailed to you or sent to you and your primary care provider in your electronic medical record. Your healthcare team will let you know if any follow-up is needed based on the results of your colonoscopy.

Additional Details

Are there alternatives to colonoscopies?

There are other ways to screen for colon cancer. These include:

  • Stool tests, such as the fecal immunochemical test (FIT), fecal occult blood test (FOBT), stool DNA tests (like Cologuard®). These tests let you collect your stool samples at home and then return them to your healthcare provider or mail them to a lab. You will have to do these more often than a colonoscopy.
  • CT colonoscopy (also called a virtual colonoscopy).
  • Flexible sigmoidoscopy, a test similar to the colonoscopy but covering a smaller part of the colon and the anus. It does not visualize the first part of the colon.

You and your healthcare provider should discuss the type of colon cancer screening that you should have. The choice will be based on your overall risk of colon cancer, general health, any symptoms you might be having and your personal preference. You should contact your health insurer about the costs of these less conventional tests.

You should know that some of the options that are not actual colonoscopies still call for the same type of preparation (cleaning out the colon by causing diarrhea). If polyps or other abnormalities are found on the alternative testing, they cannot be removed or treated. So it is likely that you will still have to have a colonoscopy. In addition, the costs of a screening colonoscopy may be less than of a colonoscopy completed after another, positive screening test other than colonoscopy.

Can you swallow a camera in a pill to take pictures of your colon?

Currently, the pill camera test is used to view the small intestine because the small intestine is easier to clean (for visibility) (the part of your bowel between your stomach and colon). Also, the camera passes through the small intestine in two to three hours.

The pill camera is being studied for colonoscopy. There are issues, though:

  • The large intestine (colon) is wide and has folds and creases.
  • It can take as long as 36 hours to pass the pill camera through the colon.
  • The colon is not as easy to get and keep as clean as the small intestine.

Can you have a colonoscopy while you have your period?

The answer to this question is yes. You might want to wear a tampon if you have your period.

Can you have colonoscopy when you are pregnant?

A pregnant woman should always consult her obstetrician before having any kind of procedure. If you are having a colonoscopy for screening, it is best to wait after pregnancy. However, colonoscopy is generally believed to be safe during pregnancy.

What are the recommendations for scheduling your first and later colonoscopies?

If you are a person of average risk for colorectal cancer, the recommendation is to get your first screening test at 45. This might be a colonoscopy or a stool test. If your risk is higher or you have certain symptoms, your healthcare provider might suggest a colonoscopy or other screening test earlier than age 45. The incidence of colorectal cancer in African Americans has been increasing, and survival rates in those with colon cancer are worse than those for other groups.

You should discuss when to start screening with your healthcare provider. There are other sets of guidelines. For instance, the American Cancer Society suggests that screening for average risk people and African Americans start at age 45.

Follow-up colonoscopies will depend on the results of the first one. If you have no polyps and low risk, you might be able to wait 10 years before having another one. If you do have polyps and are considered high-risk, you might have to have a yearly procedure. (A colonoscopy every 10 years is the general rule for people who are not at high risk.)

Regular screening should be done through the age of 75. After that, you and your healthcare provider can decide on further screening needs.

Can a colonoscopy find parasites?

In the case of some parasites, like whipworms, the answer is yes. However, a colonoscopy is not the usual way to diagnose parasites.

Can a colonoscopy be used to diagnose endometriosis?

If you are a woman with endometriosis, you may have symptoms that affect your bowel, such as pain or bouts of constipation mixed with diarrhea. Your gynecologist might suggest a colonoscopy to rule out bowel problems. Usually, the endometrial tissue does not protrude through the bowel so it cannot be seen on a colonoscopy. Such tissue often sticks to the outside of the bowel or to other tissue in the area.

Can a colonoscopy be used to diagnose prostate cancer?

No. A colonoscopy is not designed to find prostate cancer. However, some doctors may choose to perform a digital rectal examination and a prostate examination before inserting the colonoscope. Men may believe that that their prostates have been examined, but this might not be true. It is a good topic to bring up with your doctor before a colonoscopy.

Here is a final thought about colonoscopies. Many people avoid them because they find the idea embarrassing and the preparation to be unpleasant. However, people often ask themselves and their care providers how we can prevent something from happening. Here is one way: colonoscopies can stop colon cancer before it starts.


Cleveland Clinic's Bowel Preparation Instructions

Last reviewed by a Cleveland Clinic medical professional on 10/27/2019.


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