Virtual Colonoscopy (VC)
What is Virtual Colonoscopy?
Virtual Colonoscopy (VC), also referred to as CT colonography, is a safe exam used for colon polyp screening. The entire colon lining can be seen with VC. A computed tomography (CT) scan creates a picture of the inside of your colon. VC allows the doctor to see your colon and to take a limited look outside the colon for problems in the abdomen and pelvis. The main purpose of this exam is to screen for growths (polyps) in the lining of the large intestine (colon and rectum). Adults ages 50 years and over should have screening for colon polyps.
If a large polyp or growth is found in your colon, a standard colonoscopy may be needed to remove the polyp. "Large" polyps are those 1 cm (about ⅜ inch) or greater and should be removed because they have a higher chance of turning into cancer. A growth of this size is present in less than 5% of all patients. A nurse will arrange for the standard colonoscopy, if needed. If this occurs, you will need to have someone drive you home. By scheduling the standard colonoscopy on the same day or next day, a second bowel prep is not needed.
Doctors at UW Hospital & Clinics can also watch a small colon polyp over time. Smaller polyps, 6 mm to 9 mm (about ⅓-¼ inch), can be safely watched by having a follow up VC exam in 3 years. But small polyps can also be removed by standard colonoscopy, the same day or later, if desired.
Getting Ready for your VC Exam
|If you have diabetes, please call your doctor to discuss how your diabetes medicine (oral diabetes pills and/or insulin) doses should change before the VC. Test your blood sugar more often the day before this test. Also check your blood sugar the morning of your test. If your blood sugar level is low (less than 70 mg/dl) or if you have symptoms, take some glucose tablets or drink 4 ounces of a clear liquid that contains sugar. Always recheck your blood sugar level to make sure it stays above 70. We may still be able to do the VC unless you need to eat solid food to keep your blood sugar at a normal level. If the blood sugar ever gets too high or too low and you can't bring it back to normal, call your primary care or diabetes doctor.|
To prepare for this exam, you must clean your colon. Three days before the exam, try to avoid foods that are digested slowly (corn, peas, popcorn, nuts, and fruits with skins or seeds) because they may interfere with your prep. The entire day before your exam, follow the guidelines in your bowel prep kit that includes laxatives and the special clear liquid diet. If you feel you cannot complete the bowel prep, tell the VC nurse before your exam.
If you get diverticulitis before your VC exam, contact your doctor first, and then contact the VC office to reschedule your exam for at least six weeks after your treatment is complete to allow your colon to heal.
If you take Coumadin® (warfarin), Plavix® (clopidogrel) or other prescription blood thinners or antiplatelet medicines, do not stop taking them unless your doctor tells you to stop them. It is safe to have the VC exam while taking these medicines. If a polyp is found that should be removed, we will consult with your doctor who can set up the standard colonoscopy at a later date.
If your doctor tells you to stop your blood thinner or anti-platelet medicines so that you can have a standard colonoscopy if a polyp is found, please also stop iron tablets 5 days before your exam.
If you do not take Coumadin® (warfarin), Plavix® (clopidogrel) or other prescription blood thinners or anti-platelet medicines and would like to have the option of a same-day standard colonoscopy if a polyp is found, you must stop iron tablets 5 days before your exam. Taking iron does not affect your VC exam, so if you would not be able to have a standard colonoscopy the same day because you would not have a driver, or you have other plans, you may continue taking it. If you have any questions or concerns about stopping a medicine please contact your doctor.
Take all other prescribed medicines with sips of water before your VC (if you have diabetes, see the box on page 1). Do not eat or drink after midnight on the night before the exam.
When to arrive for your VC Exam
We will contact you by phone to remind you of the date for your VC exam. You do not need to have a family member or friend drive you to the VC exam, as you will not be given any medicine that will make you sleepy. If you need a standard colonoscopy the same day, then you will need to arrange for someone to drive you home.
During the VC Exam
The VC exam most often takes 15 minutes or less to complete, but allow yourself up to 45 minutes total for changing clothes and talking with the CT technologist. You will not need pain or sedation medicine or an IV for this exam. You will be asked to change into a hospital gown for the exam. You will be taken to a CT exam room where you will lie on the CT exam table. A small tube will be gently placed a very short distance into your rectum (this feeling is like having a digital rectal exam). Carbon dioxide will be placed slowly into your colon. The exam should not be painful, though you may have some abdominal fullness, discomfort, or cramping during the exam. You may feel the urge to have a bowel movement. These feelings should go away as soon as the exam is over. Pictures are taken of your abdomen and pelvis while you are lying on your back and then on your stomach. You will be asked to hold your breath for about 10 seconds while the CT scanner takes pictures.
After the VC Exam
You will be asked to give the CT technologist a phone number where the VC team can call you with your colon results. Many patients return to work or other activities after the exam is over.
- If you wish to have a polyp removed on the same day as your VC, please do not eat or drink until you hear from us. If you need to have a standard colonoscopy, the VC team can arrange this second exam for the same day as long as you have not eaten or had any liquids to drink.
- If you take Coumadin® (warfarin), Plavix® (clopidogrel) or other prescription blood thinners or anti-platelet medicines, you may resume your normal diet after the exam. If a polyp is found that should be removed, standard colonoscopy will be set up at a later date by your doctor's office.
A VC team member will call you with the colon results in about two hours. If you do not have colon polyps, you will be told to return to your normal diet. If you have colon polyps, a member of the VC team will review the options with you and help arrange further care as needed.
VC also allows the doctor to take a limited look outside the colon for problems in the abdomen and pelvis. If any other problems are seen outside your colon, the results will be sent to your doctor in the full VC report. If you have not heard from your doctor about any other results within 2 weeks, we suggest you call his or her office to follow-up.
To speak to the VC Program Assistant or Nurse call the VC Program Office at 608-263-9630 or 608-263-8587.
If you need to reschedule, call (608) 263-XRAY (9729). If you need to change your visit please provide a notice of five business days.
If you have an urgent concern after normal business hours, please contact your primary care doctor's on-call service.
If you are in need of immediate medical help, call 911 or go to the nearest Emergency Room.
The Spanish version of this Health Facts for You is #6238.
The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Any duplication or distribution of the information contained herein is strictly prohibited.
Last Updated: 04/29/2011
Copyright © 04/27/2011 University of Wisconsin Hospitals and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#5995
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