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Computed Tomography CT Colonography (Virtual Colonoscopy)

A CT Colonography is a minimally invasive exam, using CT (Computed Tomography) scanning to obtain an interior view of the bowel.

The purpose of this test is to screen for polyps and/or cancer in the colon. A polyp is a growth that can arise from the inner lining of the intestine. Some polyps may grow and turn into cancer. Colorectal cancer is the third most frequently diagnosed cancer and second leading cause of death in men and women.

A CT Colonography uses special X-ray equipment and sophisticated computers to produce 2-dimensional cross-sectional images. The computer then generates a 3-dimension model of the abdomen and pelvis which the radiologist (a physician who specializes in interpreting radiology exams and images) uses to view the bowel in a way that simulates traveling down the inside of the colon. That is why it is often called a ' Virtual Colonoscopy. It is an excellent alternative for patients who are elderly or those who have clinical factors, (such as shortness of breath), that increase the risk of complications from a full colonoscopy.

Before Your Procedure

  • It is extremely important to clean out your colon the night before your CT scan so the radiologist can clearly see any polyps that may be present. The ordering physician or clinic will provide you with the prep. The most commonly used preparations are Go-Lately or Magnesium Citrate.
  • In addition, you should limit food intake to clear liquids such as broth, tea or juice for 24 hours prior to your CT scan. You will be able to resume your normal diet immediately following the exam.
  • Failure to be fully prepped the day of the exam will result in rescheduling of the exam.

During Your Procedure

  • The CT technologist will give you a small 8 oz bottle of oral contrast, which contains a mixture of gastrografin and water. The oral contrast will need to be drunk 2 hours prior to scan time. The purpose of this contrast is to help the radiologist better distinguish stool from polyps. Once the 2 hours have passed, the technologist will bring you into the scan room and place you on the CT table.
  • A small, flexible tube will be inserted approximately 2 inches into your rectum. This allows air (CO2) to be gently pumped into the colon using a hand held squeeze ball that the technologist uses to let in small amounts of CO2. Sometimes a retention balloon is inflated on the rectal tube to help keep the tube positioned correctly. The purpose of the gas is to distend the colon as much as possible to eliminate any folds or wrinkles that might obscure polyps from the physician's view.
  • You will be placed flat on your back while the CT technologist pumps as much air into your colon as you can tolerate. Patients are asked to hold their breath for about 15 seconds while the images are being taken.
  • You will then roll over onto your stomach and more air will be pumped into your colon to ensure proper inflation.
  • The CT scanner will then repeat the scan while on your belly. The vast majority of patients who have a CT Colonography report a feeling of moderate cramping or fullness when the colon is inflated during the exam as if they need to pass gas. Significant pain is not common.

After Your Procedure

  • A radiologist will read the exam and the report will be sent to your ordering physician. The ordering physician will get your results within 5 business days.

Providing safe, quality patient care is our highest priority. To help ensure quality and safety, we ask that you do not bring young children with you to your appointments, as children are not allowed to accompany you during Imaging procedures. Staff is unable to monitor your child in your absence.

If you have any questions or concerns, please contact your provider.

Back to Imaging Patient Instructions

Dear Friends and Neighbors,

CentraCare care givers have been working around the clock for more than 20 months to care for you, your families and friends during COVID. We are committed to caring for every Minnesotan who needs us, and nothing will prevent us from doing so – even during these never-seen-before times.

The challenge of providing this level of care is that our hospital beds are often full. ERs in all of our hospitals are packed. And our clinical teams are exhausted. Early in the pandemic, our community stepped up in amazing ways to help us. We ask that you again join us in fighting this pandemic together.

How can you help?

  • Please get your COVID vaccines and booster shots. They are proven safe and effective in reducing COVID illness, keeping people out of the hospital, and preventing death.
  • If your situation is not an emergency, please use other care options, including:
  • If this is a medical emergency, call 9-1-1, or visit the ER.

Together, we can do this. Thank you for your support.

Ken Holmen, MD
President and CEO