What is a virtual colonoscopy?
A virtual colonoscopy is different from a regular colonoscopy. The virtual colonoscopy is performed in the radiology department of a hospital or medical center. No sedatives are needed and no scope is used. You will lie on your left side on a narrow table that is connected to a CT scan machine.
A small, flexible tube will be inserted into your rectum. Air is pumped through the tube to make the colon bigger and easier to see. Pumping air into the colon can create cramping or gas pains.
After this is done, you’ll be asked to lie on your back as the table slides into a large tunnel through the machine, where x-rays create images of your colon.
A regular colonoscopy may also need to be done (on a different day) after a virtual colonoscopy if:
- No cause for bleeding or other symptoms were found. Virtual colonoscopy can miss some smaller problems in the colon.
- Biopsy or polyp removal is needed.
Your doctor will most likely recommend a conventional colonoscopy instead of a virtual colonoscopy for the majority of patients. The reason is that virtual colonoscopy does not allow the doctor to remove tissue samples or polyps. This is important because some polyps can be precancerous and must be removed to eliminate the possibility of turning into cancer. In addition to removing polyps, your doctor may want to take additional biopsies to rule out certain conditions in conjunction with symptoms you experience. This can only be done with a conventional colonoscopy.
How to prepare for either test
Everyone undergoing any type of colonoscopy, virtual or traditional, must completely empty their bowels before the exam. Both tests require a bowel prep and clear liquid diet, specified by your doctor.
Risks for a virtual colonoscopy
- Radiation exposure. The risk of radiation exposure remains uncertain, although it is significantly lower radiation than one is exposed to during standard CT scans.
- The medications to prepare for the test can cause nausea, vomiting, bloating, or rectal irritation.
Differences between virtual and conventional colonoscopy include:
- Virtual colonoscopy uses no sedation, and patients are usually able to go back to their normal activities right away after the test. Conventional colonoscopy involves sedation, and usually the loss of a work day.
- Conventional colonoscopy uses the same prep as a virtual and allows for biopsies at the time of the procedure, thus no need for patient to repeat prep and have a 2nd procedure if something abnormal is found on the virtual colonoscopy.
- Conventional colonoscopy has a lesser margin for missing smaller problems in the colon.
- Screening conventional colonoscopy generally covered by most insurance companies at 100%.
- Virtual colonoscopies may not be covered by insurance and can be a very expensive out of pocket cost for a patient.
- Not all medical facilities are currently performing virtual colonoscopies.