Colonoscopy - What to Expect

This information was reprinted with permission. © 2008 American Society of Clinical Oncology. All rights reserved. www.Cancer.net

A colonoscopy is a diagnostic examination that allows a doctor to look inside the entire colon and rectum. It is used to determine the cause of colorectal problems. It is also used as a routine screening test for colorectal cancer in people who have no symptoms.

About the procedure

During a colonoscopy, the doctor inserts a colonoscope (a long, thin, flexible tube) into the anus. The tube is slowly advanced through the rectum and the full length of the colon. The doctor views the image from the colonoscope on a video monitor. If the doctor finds an abnormal growth, or polyp, in your colon, a sample of tissue or the entire polyp can be removed for examination (biopsy) using a tool at the end of the colonoscope. When the examination is complete, the colonoscope is slowly removed from the body.

The medical team

Most colonoscopies are performed by a gastroenterologist with the help of a nurse.

A gastroenterologist is a medical doctor who has completed five to six years of specialized training in gastroenterology, the study of the normal function and diseases of the esophagus, stomach, small intestine, colon and rectum, pancreas, gallbladder, bile ducts, and liver. A gastroenterologist receives specific training in endoscopy (the use of a thin, flexible tube with an attached light and view lens to look inside the body) and how to interpret the results of endoscopic studies to make treatment recommendations.

Questions to ask your doctor

Before your colonoscopy, consider asking your doctor the following questions:

  • Who will perform the colonoscopy, and who else will be in the room?
  • What will happen during the colonoscopy?
  • How long will the procedure take?
  • Will it be painful?
  • Will I receive anesthesia?
  • Are there risks associated with having a colonoscopy?
  • What if I don't have this examination?
  • Will I need to avoid any activities after the colonoscopy?
  • When will I learn the results?
  • Who will explain the results to me?
  • What further tests will be necessary if the test results indicate cancer?

Preparing for the procedure

When you schedule the examination, you will get detailed instructions on how to prepare for your colonoscopy. Review with your doctor or nurse what you need to do to prepare for your colonoscopy, and whether you should take your regular medications that day. In addition, tell your doctor about all medications you are taking, as well as any drug allergies or medical conditions you have.

Because your colon must be empty, you will need to be on a diet of clear liquids for one to three days prior to the procedure. That means eating only foods such as fat-free bouillon or broth, black coffee, strained fruit juice, and gelatin.

In addition to the liquid diet, you will need to take a laxative or give yourself an enema the day or night before the colonoscopy. If your doctor prescribes a laxative, it will either be given as a pill or as a powder that you’ll mix with water before drinking. In either form, the laxative will make you use the bathroom frequently. Completely cleansing your bowel will ensure a thorough examination.

You will be asked to review and sign a consent form that states you understand the risks of having the colonoscopy and agree to have the test done. Talk with your doctor about any concerns you have about the colonoscopy.

During the procedure

A colonoscopy usually takes 30 to 60 minutes to complete. Before the procedure begins, you will be given pain medication and a sedative (medication that causes drowsiness) through an intravenous (IV) line in your arm. This will help you relax and reduce the discomfort you might otherwise feel from the colonoscopy. (You may feel a slight stinging where the IV needle is inserted.) You will need to change into a hospital gown.

You will lie on your side on an examining table in a private room, with a sheet draped over your body. As the doctor guides the scope through the curves of your colon, you may need to change your position slightly to allow better access. The colonoscope inflates your colon by blowing air into it; this provides the doctor a better view of the colon lining.

Though rare, there is a risk that the colonoscope could puncture the colon wall. Removing a polyp or taking a tissue sample from the colon usually does not cause pain. However, bleeding may occur at the site of a biopsy or where a polyp is removed. The doctor can stop the bleeding using tools passed through the colonoscope.

Generally, the pain medicine and sedative you receive before the colonoscopy should limit pain you may feel during the procedure. You may feel cramping; taking slow, deep breaths may alleviate this discomfort. You may also feel discomfort from lying still for an extended period of time.

After the procedure

You will stay at the facility where you had the colonoscopy for up to two hours while the effects of the sedative wear off, and you will need a ride home. You can expect to resume your normal activities the day after your colonoscopy. If you feel severe abdominal pain or have a fever, bloody bowel movements, dizziness or weakness, call your doctor immediately.