Getting Ready for Your Virtual Colonoscopy (VC)
(Routine VC Prep)
What is Virtual Colonoscopy?
Virtual Colonoscopy (VC), also referred to as CT colonography, is a less-invasive, safe exam
used for colon polyp screening. The entire colon lining can be seen with VC. A computed
tomography (CT) scan creates a 3-D picture of the inside of your colon which allows the doctor
to “fly” through the interior of the colon without having to insert a colonoscope. VC also allows
the doctor 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 would like to have the option of a same-day standard colonoscopy if a polyp is found, stop
taking iron tablets five days before the 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. You may take all other
prescribed medicines before your VC (if you have diabetes or are taking prescription blood
thinners or anti-platelet medications, see the boxes on page 2).
Three days before the exam, try to avoid foods that are digested slowly (corn, popcorn, potato
skins, nuts, fruits with skin or seeds, uncooked or raw vegetables) because they may interfere
with your prep.
The Day Before Your Exam (Prep Day)
Proper bowel cleaning is needed for the best exam! To get a clean and empty colon you will start
to prepare the day before your exam. Both a clear liquid diet and the contents of the bowel prep
kit are needed to clean out the colon. The bowel prep kit contains laxatives and contrast
medicines. The laxatives will help clean out the bowel for the exam. The contrast will help to
highlight any stool or fluid left in your colon on the VC pictures.
Starting at midnight the entire day before your exam (prep day), you may drink as many clear
liquids (see below) as you want unless you are under a fluid restriction by your doctor. If you
are under a fluid restriction, please speak with your doctor to make sure this prep is right for you.
Drink only clear liquids for breakfast, lunch, dinner, and snacks. Do not eat any solid foods.
Drink plenty of fluid to avoid dehydration and to make the laxative work better. Avoid red or
purple liquids (i.e., red Jell-O , cranberry juice, purple sports drinks). Clear liquids include:
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.
If you get DIVERTICULITIS before
your VC exam, contact your doctor first
for treatment. 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 PRESCRIPTION BLOOD
THINNERS OR ANTI-PLATELET
MEDICINES, do not stop taking them
unless your doctor tells you to stop them. Some
examples include: Coumadin® (warfarin),
Plavix® (clopidogrel), Effient® (Prasugrel),
Pradaxa ® (Dabigatran). VC is often
recommended for patients taking these types of
medications because it is felt to be too great a
risk to stop the blood thinner for a standard
colonoscopy. VC can safely evaluate your
colon without stopping these medications. 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 same-day standard colonoscopy if a
polyp is found, you must discuss how long to
stop the medicine and any special instructions
to do so safely with the doctor who prescribed
the medicine for you.
Please stop iron tablets 5 days before your VC
exam, only if you will also be stopping the
blood thinner or anti-platelet medication.
Otherwise you may keep taking iron.
ξ Drink with a straw to lessen
ξ For a sore bottom after a
bowel movement, cleanse with
baby wipes and apply a
protective ointment such as
A+D® or Vaseline®. TUCKS®
medicated cooling pads may
also provide relief.
Gatorade , Powerade (sports drinks with electrolytes are recommended to help with
Water, tea, or coffee (no cream or milk; sugar or honey is okay to add)
Vitaminwater , Crystal Light
Bouillon or broth (chicken, beef, or vegetable)
Jell-O , Popsicles (no fruit or cream added)
Apple, white grape, or white cranberry juice (no orange, tomato, grapefruit, or prune
Soda such as Sprite , 7-Up , ginger ale, or any cola
Clear hard candy, gum
Lemonade (with no pulp), iced tea
Clear liquid protein drinks such as Ensure Clear TM, or Resource Breeze
Follow the Bowel Prep medicine schedule. If you take other medicines, take them at least one
hour before or at least one hour after taking the laxative (magnesium citrate). If you wish, you
may put the magnesium citrate and barium sulfate in the refrigerator. Or, you may drink them at
room temperature. Do not put the Omnipaque (iohexol) in the refrigerator and do not store the
bottle where it would be in direct sunlight.
You may have as many clear liquids as you like between each step and up until midnight.
Step 1 – anytime in the morning before 11AM: Take the two Bisacodyl tablets (5 mg
each) with 1 glass (8 ounces) of clear liquids. Do not chew or crush them. Do not take
them within 1 hour of taking an antacid. This will gently move your bowels (6-8 hours
after you take this medicine) to help the laxative taken in Step 2 work better. You can
take these tablets and still do normal activities because they will rarely cause diarrhea.
Step 2 – between 2 and 6 PM: Drink one bottle
(296 mL) of magnesium citrate. Follow this
with at least 4 to 6 cups of clear liquids before
Step 3. This is a laxative, so you should begin to
have closely spaced bowel movements. You will
want to be near a restroom. The time it takes for
the laxative to start working varies for each
person. Wait at least 2 to 3 hours from the time
you take the first bottle of magnesium citrate
before going on to Step 3.
Step 3 – between 4 and 9 PM: Step 3 should begin 2-3 hours after the start of Step 2.
o Drink the entire 225 mL bottle of liquid barium sulfate suspension found in the prep
kit. This is a contrast medication.
o Drink the second bottle (296 mL) of magnesium citrate. Follow this with at least 4 to
6 cups of clear liquids before Step 4. This is a laxative and will continue the process
of cleaning out the colon. Wait 2 to 3 hours before starting Step 4.
Step 4 – between 6 and 11 PM: Step 4 should begin 2-3 hours after the start of Step 3.
Omnipaque (iohexol) is another contrast medicine that helps highlight fluid in your
colon. The bottle says it is for “injection,” but this medicine can also be taken orally,
meaning you drink it. We want you to drink this medicine so that it will be in your colon
by the next morning of your exam.
The plastic bottle has a pull-tab on the top, but you do not need to pull this. Instead, twist
the entire top to remove it. Also remove the black rubber stopper before drinking the
Drink the entire 50 mL bottle of Omnipaque (iohexol) 350 mgI/mL. You may mix it in 8
ounces of clear juice, water, or soda and drink. Or, drink the Omnipaque and then follow
it with 8 ounces of clear juice, water, or soda. You do not need to drink it quickly unless
you want to.
You may keep drinking clear liquids until midnight.
The Day of Your Exam
Do not eat or drink anything after midnight on your exam day until you are advised to
after your exam. You may take your daily medicines as prescribed with small sips of water. If
you haven’t been able to have a bowel movement or to finish the prep kit, please call the VC
office to discuss if the exam can still be performed or if we need to reschedule the exam for a
If you have diabetes, test your blood glucose level more often when you can’t eat as well as
before your exam. You should adjust your insulin or oral diabetes pills as discussed with your
doctor. Resume your normal schedule after you receive the exam result phone call and are
eating again. If your blood glucose level is low (less than 70 mg/dl) or you have symptoms,
please drink a clear liquid that contains sugar or take glucose tablets. Always recheck your
blood sugar level to make sure it stays above 70. We can still do the exam unless you need to eat
solid food to maintain your blood glucose. It is better to maintain your blood glucose than to
have the exam. We can always schedule your VC in the future.
You do not need to have a family member or friend drive you to and from 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 for that
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
and then 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,
Bowel Prep Complete!!!
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 right side. You will be asked to hold your breath for about 10 seconds while
the CT scanner takes pictures.
After the 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.
ξ 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.
ξ If you take prescription blood thinners, anti-platelet medicines, or do not wish to have a
same-day standard colonoscopy, you may resume your normal diet right 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 and any medicines you may have
stopped. If you have colon polyps, a member of the VC team will review 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.
For additional information on the virtual colonoscopy exam and prep, please see our video at
VC Nurse: 608-287-2192 VC Program Assistant: 608-287-2370
If you have an urgent concern after normal business hours please contact your primary care
doctor’s on call service. If your referring physician is from outside the UW Health system, you
may call the paging operator for urgent VC related concerns at 608-263-6400 and ask for the
radiology resident on-call.
If you are in need of immediate medical help, call 911 or go to the nearest Emergency Room.
If you need to reschedule for any reason please call 608-287-2192.
Your health care team may have given you this information as part of your care. If so, please use it and call if you
have any questions. If this information was not given to you as part of your care, please check with your doctor. This
is not medical advice. This is not to be used for diagnosis or treatment of any medical condition. Because each
person’s health needs are different, you should talk with your doctor or others on your health care team when using
this information. If you have an emergency, please call 911. Copyright © 1/2015 University of Wisconsin Hospitals
and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#7100