Virtual Colonoscopy

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.

What are the risks and benefits?

Some of the benefits of a virtual colonoscopy are:

• It only lasts about 15 minutes.
• It produces detailed 2D and 3D images as clear as what a provider can see on a traditional colonoscopy.
• There’s a faster recovery because you don’t have sedation.
• It’s less invasive because providers don’t have to insert a scope.
• There’s less risk of injury to your colon than traditional colonoscopy.

It’s a good option if you can’t have sedation or a traditional colonoscopy for any reason. Because it can take pictures of your entire bowel, it works well if you have a bowel obstruction or narrowed parts in your bowel. It can also show problems in your kidneys, liver or other parts of your abdomen.

Risks and limitations of the test include:

• Bowel perforation from inflating your bowel with air (this is rare)
• Exposure to small amounts of radiation (the exposure levels are safe)
• It can miss smaller polyps that traditional colonoscopy may catch

This test may not be safe for everyone. This is why your provider will review your medical history and medications beforehand.

What should I expect after?

After your virtual colonoscopy, you can go back to your typical activities and eat and drink normally. Because it doesn’t require anesthesia, virtual colonoscopy usually has very little or no recovery time.

You may have some side effects, like excess gas from the air that was pumped into your colon. The gas may cause some cramping or bloating, but this is normal.

What do results of a virtual colonoscopy mean?

If your provider finds an abnormality or a polyp on your virtual colonoscopy, this doesn’t mean you have colorectal cancer. But you’ll need a follow-up colonoscopy so your provider can remove the polyp. Sometimes, they can do the colonoscopy on the same day, as you’re already prepped.

As a virtual colonoscopy gives a wider view of other organs in your pelvis, there’s a chance your provider can see issues outside of your colon. If this happens, they’ll order additional testing on those organs.

If your results are normal, it means your provider didn’t see anything irregular in your colon. Ask your provider when you should have your next colorectal cancer screening. If you have a low risk of colorectal cancer, you may need a repeat virtual colonoscopy every five years.

How accurate are the results?

Several studies show virtual colonoscopy finds large polyps and cancer at about the same rate as a typical colonoscopy. But the accuracy can vary depending on the size of the polyps. It’s generally more accurate in detecting polyps larger than 10 millimeters. It’s slightly less effective at finding polyps less than 6 millimeters.

When should I call my healthcare provider?

Seek medical care right away if you notice these symptoms after your virtual colonoscopy:

• Blood in your poop or blood coming out of your butthole
• Dizziness
• Fever
• Severe abdominal pain