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Virtual Colonoscopy


A virtual colonoscopy is a procedure to examine the inside of your colon (large intestine). Healthcare providers also use a CT scan or MRI to take pictures of your colon. If you have CT scan, air or carbon dioxide (gas) is put in using a small, bendable tube into your rectum to expand your colon. In an MRI colonoscopy, warm water or solutions with dye may be used so healthcare providers can clearly see the inside of your colon.


The week before your procedure:

  • Ask if you need someone to drive you home after your procedure.
  • A contrast material that contains the iodine may be used during your procedure. People who are allergic to shellfish (lobster, crab, or shrimp) may also be allergic to dyes or iodine. Tell your healthcare provider if you have allergies to any food or contrast material.
  • Ask your caregiver if you need to stop using aspirin or any other prescribed or over-the-counter medicine before your procedure or surgery.
  • Bring your medicine bottles or a list of your medicines when you see your caregiver. Tell your caregiver if you are allergic to any medicine. Tell your caregiver if you use any herbs, food supplements, or over-the-counter medicine.
  • Tell your healthcare provider if you are afraid of closed spaces or have any metal implants in your body. An MRI cannot be used on people with implanted metal objects, such as a pacemaker, as it may cause serious injury. A watch, prosthesis, and other metal objects are not allowed inside the MRI room as they may interfere with the pictures.
  • Tell your healthcare provider if you have had other similar procedures before and when they were done. These may include a past colonoscopy, barium enema (lower GI procedure), or sigmoidoscopy.
  • Tell your healthcare provider if you have other diseases, such as severe inflammation of the bowel or kidney problems. Certain medicines used to empty your bowel may not be good for you.
  • You may need to have blood, urine, or stool tests. Ask your healthcare provider for more information about these and other tests that you may need. Write down the date, time, and location of each test.
  • Directions for eating and drinking:
    • A clear liquid diet or a diet that helps to clean out your colon may be started 1 to 2 days before your procedure. Clear liquids may include plain gelatin, unsweetened fruit juices, clear soup, or broth.
    • Do not eat foods with residue or fiber that are not easy to digest. These include fruits, vegetables, cereal, nuts, peas, beans, popcorn, and tomatoes. Ask your healthcare provider for a list of foods to avoid. If you are having an MRI colonoscopy, you may also need to avoid any food that contains manganese (a metal), such as chocolate.
  • If an MRI colonoscopy will be done, you may need to drink a contrast material 2 days before your procedure. The contrast material will make the colon easier to see.

The day before your procedure:

Your bowel needs to be empty before your procedure so that better pictures may be taken. Your healthcare provider will give you directions for emptying your bowel.

The night before your procedure:

  • Bowel preparation:
    • You may need a liquid medicine called an enema. An enema uses warm water that is put into your rectum to help empty your bowel.

The day of your procedure:

  • Write down the correct date, time, and location of your procedure.
  • Bowel preparation:
    • Do not eat or drink anything on the morning of your procedure. The images of your colon may not be seen clearly if it is not totally empty.
    • You may need an additional enema, using warm water, the morning of your procedure.
  • Healthcare providers may insert an IV into your vein. A vein in the arm is usually chosen. Through the IV, you may be given liquids and medicine.
  • You or a close family member will be asked to sign a legal piece of paper (consent form). It gives your healthcare provider permission to do the procedure. It also explains the problems that may happen and your choices. Be sure all your questions have been answered before you sign this form.


What will happen:

  • You will be taken to the radiology room. Your healthcare provider may give you medicine that will relax your colon. You will be asked to lie on your left side or on your stomach and raise one or both knees toward your chest. Your healthcare provider will examine your anus and use a finger to perform a digital rectal exam (DRE) to check your rectum. Your healthcare provider will gently insert a thin, flexible tube in your rectum. If a CT colonoscopy will be done, he will put air or carbon dioxide into the tube. In an MRI colonoscopy, warm water or solutions with dye will be passed through the tube and into your colon.
  • During your procedure, the bed you are lying on will be moved inside the CT or MRI tube. Pictures will be taken as the bed or table moves and as you change positions. You may be asked to lie on your back or stomach. If the bowel is not expanded enough, more air or gas will be pumped into your rectum. You will have to hold your breath and stay still as each picture is taken. When the procedure is finished, your bed will be moved out of the CT or MRI tube. The small tube in your rectum will then be removed.

After your procedure:

You may pass some air that is left in your colon. When your healthcare provider sees that you are okay, you will be allowed to change clothes and go home. If your healthcare provider wants you to stay in the hospital, you will be taken back to your hospital room.


  • You cannot make it to your appointment on time.
  • You have a fever.
  • You have constipation and the medicines are not helping to empty your bowel.
  • You have questions or concerns about your procedure.

Seek Care Immediately if

  • You are not able to eat or drink, or you are urinating less or not at all.
  • You have blood in your bowel movement.
  • You are not able to have a bowel movement.
  • Your abdomen becomes tender and hard.
  • Your signs and symptoms are getting worse.
  • Your vomit has blood or bile in it.


  • CT scanning exposes you to radiation that is released when x-ray pictures are taken. If dye is used, it may cause you to have headaches, nausea, vomiting, flushing, or itchiness. You could also have an allergic reaction to the dye. You may feel a little pain or discomfort as the small tube is placed inside your rectum. Your colon may get perforated (torn) due to increased pressure. If this happens, you will need to stay in the hospital and have surgery on your colon.
  • Without this procedure, diseases may not be diagnosed and proper treatment may be delayed. The signs and symptoms you have may continue and worsen. You may have problems eating, digesting food, or moving your bowel. This may lead to other serious medical problems, such as a blockage of your colon.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.