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Everything you need to know about Computed Tomography (CT) & CT Scanning

Other Contrast

question1. Do we ever use rectal contrast and if so when and why?
question2. What is virtual colonoscopy and what is the patient prep for the study?

Virtual colonoscopy is a new exam that is used for screening the colon for polyps. It is usually done in asymptomatic patients as part of the American Cancer Society's screening program but is also used in patients with failed classic fiberoptic colonoscopy.

Virtual Colonoscopy: Facts

The literature has shown it to be as accurate as classic colonoscopy with any the the risks of classic colonoscopy. A series of quotes from the literature define its success.

Illustrative cases

Here are 3 cases of colon cancer and polyps detected with CT Virtual colonoscopy:

IV contrast image
IV contrast image


Patient Prep Instructions

  • 1. In the morning, prepare the GoLYTELY/NuLYTELY solution according to the instructions on the package and refrigerate.
  • Drink only clear liquids for breakfast, lunch and dinner until 12 midnight.
  • Breakfast (around 8:00 A.M.) With clear liquid Breakfast:  Shake well and drink one 20 cc bottle Tagitol
  • Lunch (around 12:00 P.M.): With clear liquid lunch:  Shake well, then mix the second bottle of Tagitol with 8 ounces of water.  Drink 4 ounces (save the remaining 4 ounces for dinner).
  • From now until you go to bed it is very important to drink at least 8 ounces of water every hour so you do not become dehydrated.
  • Approximately 3:00 pm: Drink one, 8 oz. glassful of GoLYTELY/NuLYTELY, every 15 min. until gone.
    • You will have drunk several glasses before the first loose, watery bowel movement. At first, you may feel slightly bloated.
    • It will take approximately 3-4 hours to finish the GoLYTELY/NuLYTELY.
    • Diarrhea will continue at least 1 hour after you finish
  • Dinner (approximately 5 P.M.) With clear liquid dinner: Drink the remaining 4 ounces of Tagitol.
  • 30 min. after finishing the GoLytely, take 2 Bisacodyl (5mg) tablets
  • Bedtime: Take the 50ml bottle of Omnipaque (injection 350mgI/ml) by mouth mixed with 5-6oz of water, clear soda or Gatorade and drink. To open the bottle: remove the green top by popping it off – it does not twist. Remove the silver metal and pull out the black stopper.


question3. Do we ever place contrast in the bladder similar to a cystogram and if so why?
question4. What contrast do you put in the bladder (type and volume)?


© 1999-2021 Elliot K. Fishman, MD, FACR. All rights reserved.