Virtual colonoscopy is a minimally invasive CT scan requiring no sedation. This procedure helps your doctor assess the health of your rectum and colon (large intestine). Virtual colonoscopy takes less than a quarter of the time of conventional optical colonoscopy (OC), and there is virtually no risk of colon perforation or complications (<0.0001%). It is also significantly more comfortable than a traditional optical colonoscopy.
Virtual colonoscopy is often requested to screen for precancerous growths (polyps) and cancerous tumors in the large intestine and rectum (colorectal cancer, or CRC). This procedure is also done to test for recurrence of colon cancer in those who have had surgery or treatment.
Any polyp left untreated can develop into cancer over time, usually after a few years. Therefore, finding precancerous lesions in the large intestine and rectum as early as possible significantly improves the chances of successful treatment. With early detection, over 90% of colorectal cancers can be prevented or curatively treated.
Differences Between Virtual Colonoscopy (VC) and Optical Colonoscopy (OC)
Advantages of VC
- VC is less invasive. A small tube is inserted into the rectum but is not advanced through your colon like a traditional optical colonoscopy.
- VC is safer. Since VC uses gas and computed tomography to visualize the colon, there is virtually no risk of perforation or complications.
- VC takes less time, as patients are sedated for OC. Procedure and recovery time for sedated patients is typically 120 minutes (four times longer than VC).
- VC does not require patients to arrange for a driver since no sedation is needed.
- VC can visualize inflamed or partially blocked colons, where OC cannot move past any growths.
Disadvantages of VC
- VC uses CT scanning, which exposes patients to ionizing radiation.
- A biopsy to remove a sample for diagnosis cannot be performed immediately. If a growth is found using VC, an OC will need to be scheduled to examine the polyp.
- Alberta Health Services does not cover CT scans conducted outside of the hospital. Therefore, there is a significant chance a patient’s insurance plan will not cover the cost of the procedure.
Virtual Colonoscopy Preparation
A bowel-emptying diet and laxative regimen is required to clear the colon of all solid material. We will provide you with your free custom preparation kit. The preparation kit is available for pickup at our Meadowlark Diagnostic Imaging clinic. If you live out of town, we will mail the kit to you. It should be in your possession at least three days before your exam. This kit contains everything you will need to cleanse your colon over the two days before your exam. The kit includes food, liquids, laxatives, and detailed prep instructions.
What Happens During my Virtual Colonoscopy?
- Once we establish eligibility for the exam, you will be given a gown to change into and then taken into the CT room.
- The technologist will position you on the bed for your scan.
- An injection of Buscopan will be given to reduce bowel motion. A small tube will be inserted into your rectum, and the colon will be gently inflated with harmless carbon dioxide gas.
- Virtual colonoscopy provides superior comfort and exam quality over traditional optical colonoscopy, as the tube does not have to be inserted past the rectum and into the colon. Complete inflation is essential for colon assessment.
- Virtual colonoscopy is performed with you lying on your back and then on your stomach to ensure complete visualization of the colon.
- During the exam, you will be asked to hold your breath for 10 to 15 seconds so specific images can be captured.
- Once enough high-quality images are taken, the technologist will help you off the bed and escort you to the change room.
- One of our radiologists will review the exam results and send a detailed report to your doctor. We try our best to send the results as soon as possible, usually within one business day.
During a virtual colonoscopy, you will be moved into the scanner feet-first, on your back at the start of the exam and then on your stomach for the remainder. Changing your body position allows us to ensure complete visualization of the colon.
A virtual colonoscopy CT scan typically lasts between 30 and 45 minutes.
Being prepared for your virtual colonoscopy is vital as it allows us take the best possible images for diagnosis. Please visit our exam prep page for very details instructions specific to VC preparation.