Patient Instructions - 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
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.