In order to encourage more people to get a baseline colonoscopy starting at age 50, the U. S Preventative Task Force expanded the list of screening options for people of average risk.  One of the screening options available is called CT colonography or virtual colonoscopy.

Virtual colonoscopy is a diagnostic medical test that produces multiple images or pictures of the inside of the body and can be used to examine the large intestine or colon for cancer and growths called polyps.  During the exam, a small tube is inserted a short distance into the rectum to allow for inflation with air while CT images of the colon and rectum are taken.

What are the advantages and disadvantages of this procedure?  How does it compare to a traditional colonoscopy?

Advantages of virtual colonoscopy

·         Even though a short tube is inserted into the rectum to inflate the colon, virtual colonoscopy doesn’t require the insertion of the long flexible scope through the rectum up into the colon.  Instead the colon is visualized by computed tomography (CT), a special type of x-ray imaging test.

·         Does not require sedation unless needed

·         Very little risk of complications since the test is mostly noninvasive

 Disadvantages of virtual colonoscopy

  ·         It may miss small polyps even though it is very good at identifying cancers and larger polyps.  Because of this, virtual colonoscopy is recommended to be repeated every 5 years instead of every 10 years with the traditional colonoscopy. 

·         The colon still needs to be cleaned out by fasting and taking a strong laxative just like for the traditional colonoscopy.  When the colon is inflated during the procedure, there may be some discomfort.

·         If a polyp is found during the procedure, doctors can’t take a biopsy or remove the polyp as they can during a standard colonoscopy.  If polyps are detected, a colonoscopy needs to be done to remove them usually on another day requiring another bowel prep.

·         Virtual colonoscopies will detect suspicious growth and other possible abnormalities outside the colon.  Even though it could be seen as an advantage, the overwhelming majority of these findings are not cancerous presenting no threat but may require a biopsy to rule it out followed by more testing and possibly unnecessary treatments.  Traditional colonoscopies are much better at detecting suspicious growths.

·         Virtual colonoscopies do expose a person to radiation.  Since this test has to be repeated periodically, this is not ideal as radiation exposure has a cumulative effect. 

Bottom line

At this time, it is important for all people over the age of 50 or those younger showing signs of possible colon cancer, to be regularly screened for this disease.  The message is people need to be screened and it would be best for everyone to discuss with their physician on which method of colon cancer screening they recommend going over the pros and cons of each.