Virtual colonoscopy uses low radiation dose equal to about a year of radiation we all get from environmental sources. Longterm risk of low-dose radiation is unclear. However, the American Association of Physicists in Medicine considers risk from dose levels, such as those used in the virtual exam, to be very small.
In traditional colonoscopy a long tube (colonoscope) is maneuvered from the rectum to the beginning of the colon. There is a small risk of colon perforation from this — approximately 1 patient per 1,000 standard colonoscopies. In virtual colonoscopy, only a very small flexible tip is placed into the rectum to gently inflate the colon. The risk of perforation from the virtual colonoscopy is far lower. Traditional colonoscopy is most often performed with sedation, which carries risk of allergic reaction and other side effects. Virtual colonoscopy does not require sedation. Most patients can go back to their daily activities. Former President Obama had his first colorectal cancer screening using virtual colonoscopy. Unlike standard colonoscopy, the virtual exam can detect unsuspected medical problems outside the colon.
While only 1 in 300 patients who get screening virtual colonoscopy will have colon cancer, up to 1 in 200 patients have been shown to have an unsuspected kidney, lung or lymph node cancer. Some of these incidental findings will require additional imaging tests, which may be associated with additional costs.