Another name for a virtual colonoscopy is computed tomography colonography or CT colonography. This imaging test combines X-rays and CT scans to take 2-D and 3-D pictures of the colon, large intestine, and rectum.

We use this virtual colon scan to screen for colon and rectal cancer. Virtual colonoscopy can help us find cancer. It can also help us see abnormal growths that may turn into cancer, called polyps. If the scan finds suspicious growths, you’ll need a colonoscopy to remove and test them.

Adults with an average risk for colorectal cancer should get routine screenings between 45 and 75. Ask your care team about continued screening if you're between 76 and 85. You don't need further screens after age 85.

When getting screened for colon and rectal cancer, you have several options. They include colonoscopy, stool tests, and imaging tests. Which you choose is based on personal preference and discussion with your doctor.

A standard colonoscopy is more invasive, but you only need to do it once every 10 years. Plus, your doctor can remove any suspicious growths they find, preventing them from becoming cancer.

You need to do stool-based screening tests every 1 to 3 years.

If you choose virtual colonoscopy for colorectal cancer screening, you'll need to have this imaging test every 5 years. During a virtual colonoscopy, we don't insert tools into the bowel, so we can’t remove polyps, and this test doesn't prevent growths from becoming cancer.

Virtual colonoscopy uses radiation, so don’t get this test if you could be pregnant.

Virtual colonoscopy is a less invasive imaging test. It still requires preparation.

Before

You may only have clear liquids for the 24 hours before your virtual colonoscopy. You also can’t eat or drink for a few hours before this imaging test. Your test instructions will tell you the time to stop eating or drinking. 

For this test, you need to empty your bowels. We will give you instructions on how to clear your bowels before the test. This may include taking pills or liquid bowel prep.  

We may also give you small amounts of barium contrast or iodinated liquids. These help the radiologist tell if there's any remaining stool in your bowel apart from polyps. Tell your doctor if you have heart, liver or kidney disease, as the barium contrast may worsen these conditions.

During

Unlike standard colonoscopy, which requires sedation, you're not under sedation for a virtual colonoscopy.

You'll wear a hospital gown for the test. A technician will operate the scanner in another room, giving instructions through a speaker. The entire exam takes about 15 minutes.

Here’s what you can expect during the test:

• You'll lie on your stomach on a narrow table. The CT scanner is a donut-shaped machine at the end of the table.
• We'll inflate the inside of your colon. We do this by placing a very small, flexible tube 2 inches into your rectum. We use a hand-held squeeze bulb to pump air gently into your colon. This helps undo any folds or wrinkles that can hide polyps. You may feel some pressure or fullness from the added air.
• The table slides into the scanner, which rotates around you to take the images. The technician will ask you to hold your breath for about 15 seconds.
• You'll then change positions and lie on your side or back. You'll hold your breath again while the scanner rotates for another set of images.

After

After the test, you can return to normal eating. You might feel a little gassy as the air in your bowels tries to escape.  

Your doctor will let you know if anything looks suspicious on your images. If so, we'll need to do a colonoscopy to take a sample or remove the growths. Virtual colonoscopy may miss small polyps. Most of the time, small polyps aren't likely to become cancer, so we may not need to take them out.  

A virtual colonoscopy also captures images of nearby areas outside the colon and rectum. If we find anything of concern in these areas, you may need more follow-up procedures.