Colon Screening: Colonoscopy vs Virtual Colonoscopy

March 2012

by Adelina Espat

colon, colonoscopyIf you’re age 50 or older, you should get screened for colorectal cancer. But, which exam should you get?

When it comes to colorectal cancer screening exams, you’ve got choices.

Many people opt for a colonoscopy. But, virtual colonoscopy also is an approved option. And, to most people, it sounds much less invasive.

So, which should you choose? Let’s compare the two.

Colonoscopy: usually done every 10 years

When you get a colonoscopy, a doctor examines your rectum and colon with a lighted tube called a colonoscope. Your doctor inserts this tube into your rectum to look for unusual tissue changes and polyps.

Polyps are small growths on your colon wall. Left untreated, they can grow larger and become cancerous over time.

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  • Polyp Removal — Your doctor can detect and immediately remove polyps during a colonoscopy. And, removing polyps can help you avoid colorectal cancer.
  • Little Discomfort – You doctor can give you medication to help you stay relaxed and comfortable during the exam.


  • Hard-to-Spot Polyps — Your doctor may not find every polyp during your exam. That’s especially true for polyps that are harder to spot, like small or flat polyps. But, a colonoscopy is still one of the most effective tests currently available.
  • Colon Cleansing — You have to cleanse your colon completely before the exam. This means you’ll take laxatives 24 hours before your colonoscopy.  And, you won’t be able to eat or drink after midnight.
  • Complications — It’s not common, but inserting the colonoscope can cause bleeding and/or tearing of the colon.
  • Insurance Coverage – The co-pay for a colonoscopy is different for each insurance provider and can sometimes be costly.

Virtual colonoscopy: usually done every 5 years

colonoscopy, colonWhen you get a virtual colonoscopy, your doctor does a CT scan of your abdomen and pelvis to create 3-D images that show polyps and other abnormalities inside your colon and rectum.


  • Less Invasive — Your doctor will insert a tube in your rectum and colon. But, it’ll be shorter than the tube used for a colonoscopy.
  • Fewer Complications — You won’t have to worry about colonoscopy complications, such as bleeding or tearing of the colon.
  • Spot More Than Polyps – Your doctor also can see things outside the colon. This makes it easier for your doctor to spot problems not just in the colon.


  • Hard-to-Spot Polyps — Like the colonoscopy, this exam may miss some polyps.
  • Colon Cleansing — You’ll still need to take laxatives 24 hours before your colonoscopy.  And, you won’t be able to eat or drink after midnight.
  • Follow-up Colonoscopy — If your doctor finds a polyp or anything else unusual during your virtual colonoscopy, you’ll need to get a traditional colonoscopy to remove the polyp or perform a biopsy.
  • colonoscopyRadiation Exposure — Virtual colonoscopy exposes you to a low dose of radiation. You’ll be exposed to more radiation than a chest x-ray but far less than a conventional CT scan.
  • Insurance Coverage — Not all providers cover the costs of a virtual colonoscopy.

No test is perfect

Neither colonoscopy nor virtual colonoscopy is the perfect screening tool. In fact, no screening exam is 100% accurate. But, research shows that both exams are good options to check for and prevent colorectal cancer.

READ ALSO: Who's more likely to get colon cancer?

Start the colorectal screening discussion at your next check-up. Your doctor can help you decide which exam is best for you and share other colorectal screening options, like the fecal occult blood test (FOBT).

Remember, screening for colorectal cancer saves lives. Don’t put off this test for fear of discomfort. Either virtual or traditional colonoscopy can work for you if you follow your doctor’s recommended screening schedule and properly prepare for whichever exam you choose.

MAKE AN APPOINTMENT: Schedule an appointment for a colonoscopy, or other colon cancer exam, at MD Anderson’s Cancer Prevention Center. Call 713-563-5360 or request an appointment online.