There are two absolutes as you approach your 50th birthday: your AARP membership is on its way and it’s time for your first screening colonoscopy. Yes, “that” exam. But there’s more than one way to examine the colon for abnormalities and suspicious growths that might morph into cancer.
A colonoscopy is the standard screening exam for detecting colorectal cancer. It uses a flexible fiber-optic scope that’s inserted into the rectum to look for and remove growths such as polyps. The patient receives intravenous sedation and is unconscious during the procedure. The other type of colonoscopy is “virtual.” It relies on a CT computerized tomography (CT) scan of the abdominal cavity to see suspicious and cancerous growths, but it does not remove them (another procedure is needed for that) and it does not require sedation. So far, so good.
Virtual colonoscopy, which is also known as a CT colonography, is particularly useful for individuals who have a contraindication to colonoscopy or who have undergone an incomplete or “failed” colonoscopy, says Jay Heiken, MD, professor of radiology and an abdominal imaging expert at MIR .
Typical candidates for virtual colonoscopy are patients who are on blood thinners that can’t be stopped, and who can’t have a colonoscopy because of the risk of bleeding. Patients with severe lung disease may benefit from a virtual colonoscopy too because sedation is risky for them. Virtual colonoscopies are (also) performed on patients who have had a ‘failed’ or incomplete colonoscopy. They are people with a very tortuous bowel, i.e. a colon that has a lot of loops or kinks in it, or a colon that has areas of narrowing due to diseases such as diverticulosis.”
In general, patient prep is the same for both exams, with the patient taking laxatives to cleanse their colon. One slight difference with the virtual exam is that the patient drinks “tagging” agents the day before their colonoscopy.“Tagging agents are small amounts of barium and/or iodine solutions that will infiltrate any retained stool,” Heiken says. “One potential problem with CT colongraphy is that some stool or fluid may remain in the colon after the patient undergoes a colon cleansing prep. This can obscure a small polyp, or allow a remnant of residual stool to be mistaken for a polyp.” The tagging agents enable the radiologist to see polyps that might be hidden within bowel fluid and distinguish them from residual stool.
Currently virtual colonoscopy is not offered to all individuals who need colorectal cancer screening because Medicare and many private insurance companies will not pay for it unless a standard colonoscopy is contraindicated or has been unsuccessful. If you don’t have a contra-indication for a standard colonoscopy and still want to have a virtual colonoscopy, you can — but it might be on your dime. You or your doctor can check with your insurance company to see if your policy will cover the examination. However, a physician referral is needed to schedule an appointment. Appointments can be made by calling our central scheduling phone number: 314-362-7111 or 877-992-7111.