CT Virtual Colonoscopy
What is a CT Virtual Colonoscopy?
CT Virtual Colonoscopy is a safe, non-invasive procedure to identify growths (polyps) in the colon. Polyps have been shown to be the precursor of many cancers in the colon and rectum (colorectal cancer), and the goal of CT Virtual Colonoscopy is to find these potentially dangerous polyps before they can cause a serious problem.
CT Virtual Colonoscopy is an alternative to conventional colonoscopy, which requires the introduction of a long tube into the rectum and is then advanced through the entire colon. Unlike optical colonoscopy, virtual colonoscopy is a minimally invasive procedure and requires no sedation. While conventional colonoscopy takes two or more hours to perform, virtual colonoscopy can be completed within a half-hour and is a far more comfortable procedure.
Who should have a CT Virtual Colonoscopy?
Colorectal cancer is the second leading cause of cancer-related deaths in the United States. According to guidelines endorsed by the American Cancer Society and other national groups, screening for colorectal cancer utilizing a technique that examines the entire colon is recommended for individuals beginning at age 50. Screening is recommended beginning at age 40 for individuals at high risk for colon cancer, including those with:
- Personal or family history of colon cancer
- Personal history of ovarian, endometrial or breast cancer
- History of chronic ulcerative colitis or Crohn's disease
Potential reasons for having a CT Colonography exam are an incomplete optical colonoscopy, low-to-average risk patients who prefer not to have a colonoscopy, and frail patients and others who are unable to tolerate a colonoscopy.
How do I prepare and what can I expect before, during and after my CT Virtual Colonoscopy?
In order to obtain the best images, bowel preparation is required. The preparation is similar to that required for conventional colonoscopy.
In addition, it is necessary to distend the colon for the best images. After you enter the examination room and are placed on the CT examination table, the nurse or technologist will insert a small plastic tip into the rectum. Air is slowly pumped through the tube to inflate the colon.
Two scans are performed, one while lying on your back, the other while lying on your stomach. The actual time of each scan is 20 seconds. There is a three-minute pause between the two scans to allow the computer to process the many images acquired. You will be asked to hold your breath for up to 20 seconds. You should remain as still as possible to produce the clearest images. After the second scan, your examination is complete. Total examination time, from the moment you enter the scan room until completion, is approximately 15 minutes.