A virtual colonoscopy is a CT scan that looks for polyps or cancer in your colon and rectum. This test uses highly detailed 3D images to see the entire length of your colon. The test is about 15 minutes long, and you don’t need sedation.

What is a virtual colonoscopy?

A virtual colonoscopy (CT colonography) is a noninvasive test that looks for polyps (growths) in your colon. It uses a CT scan and computer technology to take high-quality images of your colon from outside of your body. It gives your healthcare provider a virtual 3D tour, allowing them to see polyps that could eventually progress to colorectal cancer.

It doesn’t require anesthesia and takes only 15 minutes to complete. If your provider sees polyps during the test, you’ll need a traditional colonoscopy to remove them.

Virtual CT colonoscopy is one method healthcare providers use to screen for colon cancer. Experts recommend that everyone get a screening starting at age 45. If you have certain risk factors, you may need one sooner. Your provider can explain if a virtual colonoscopy is the best colon cancer screening choice for you

How does a virtual colonoscopy work?

A virtual colonoscopy uses imaging technology to take detailed pictures of your colon. A technician uses a CT scanner to take several pictures of your abdomen and pelvis. Then, a computer processes these pictures to create 2D and 3D images. A radiologist analyzes these images to look for polyps and other abnormalities in your colon. If found, you’ll need a traditional colonoscopy to remove the polyps.

How do I prepare for a virtual colonoscopy?

Before your virtual colonoscopy, you’ll do a bowel preparation, or “prep.” This process empties your colon of all stool (poop), so your provider can see your colon and rectum clearly. You usually do your prep the day before your virtual colonoscopy.

Your provider will give you instructions on how to complete your virtual colonoscopy bowel prep, which may include:

• Enemas. These are medicines that you put in your rectum to stimulate bowel movements.
• Laxatives. These come as liquids or powders that make you have frequent bowel movements.
• Clear liquid diet. The day before your procedure, you may not be able to eat or drink anything other than clear liquids like water, fat-free broth, apple juice and plain coffee or tea. Your provider will give you a list of things you can eat and drink during your prep.
• Fasting. You won’t be able to eat or drink for a few hours before your procedure.
• Drinking a contrast medium. This liquid helps your provider see your colon clearly on the virtual colonoscopy.

A complete bowel prep is necessary for a successful virtual colonoscopy. It will cause frequent and watery diarrhea, so plan to stay at home and near a bathroom during your prep period.

What should I expect during the test?

On the day of your appointment, wear comfortable clothing and don’t wear any jewelry. A healthcare provider will take you to a room with the CT scanner, which looks like a large, donut-shaped machine. Your virtual colonoscopy usually involves these steps:

1. After changing into a hospital gown, you lie down on an exam table.
2. The technician inserts a short tube about 2 inches into your rectum. This tube gently pumps some air into your colon, which inflates it and makes it easier to see details with the CT scanner.
3. The table slowly slides you into the CT scanner, which looks like a short tunnel. The CT scanner makes buzzing or clicking sounds as it takes pictures of your colon.
4. You lie very still while the CT scanner takes pictures. The technician talks to you throughout the process using an intercom system. They may ask you to hold your breath for a few seconds or to change positions during the test.
5. After your test is done, the table slides you out of the scanner, the technician removes the tube from your rectum and then you get dressed.

The test shouldn’t be painful. You may feel pressure in your rectum or like you need to pass gas.