Virtual Colonoscopy

Also available in PDF format Virtual colonoscopy

What is a virtual colonoscopy?

A virtual colonoscopy is a CT scan (computed tomography, or CAT scan) of the colon that uses a special X-ray machine to take detailed pictures. CT pictures are far more detailed than a standard X-ray.

CT is useful because it can show many types of organs (liver, spleen, pancreas, kidneys, lower gastrointestinal tract, colon, and rectum) at the same time.

How does the CT scan work?

Unlike standard X-rays, which produce pictures of the shadows cast by body structures of varying thickness, CT scanning uses X-rays in a much different way. Many X-ray beams are passed through the abdomen/pelvis at many angles, and special detectors measure the amount of radiation absorbed by different tissues. The X-ray tube revolves around you, and sends and records data from many angles, forming cross-sectional pictures (slices) of the area. The pictures are then reviewed on a computer screen.

Modern CT units, called spiral CT, produce higher-quality pictures in a shorter time, an important feature for children and patients who are elderly or critically ill, as well as for those who cannot hold their breath for a long time. Today’s scanners can image large regions of the body during a single 20-second breath-hold.

How should I prepare for the CT scan?

On the day before your procedure:

Note: You may eat or drink ONLY items listed in these instructions. When quantities are given, be sure to drink the entire amount.

On the Day of the Procedure

·       DO NOT eat anything before procedure.

·       At least 2 hours before the exam:

·       Insert the Bisacodyl suppository (from the LO SO Prep kit) into your rectum and gently push in as far as possible.

·       Retain the suppository for at least 15 minutes, if possible, before evacuating. Bowel evacuation usually occurs within 15 to 60 minutes.

·       Wear comfortable, loose-fitting clothing for your CT exam.

·       Do not wear clothing with zippers or snaps. Metal objects can affect the scanned image.

·       Women: Always inform your doctor or CT technologist if there is any possibility that you are pregnant.

·       After the CT scan, you can resume your normal daily activities.

How is the CT scan performed?

1.     The CT technologist will place you on the CT table, using pillows to help you maintain the correct position during the scan.

2.     For the first few scans, the table will move quickly through the scanner to check the correct starting position. The rest of the scans are made as the table moves more slowly through the hole in the scanner.

3.     A CT exam of the colon requires the use of carbon dioxide to distend your bowel. The carbon dioxide will be introduced into your colon through a small tube inserted into your rectum. The carbon dioxide will be rapidly absorbed by your body and will cause little post-procedure discomfort.

4.     The CT exam usually takes 30 to 45 minutes. When the exam is over, you may be asked to wait until the images are checked to find out if more images are needed.

What will I feel during the procedure?

·       CT scanning causes no pain, and with spiral CT, the need to lie still for any length of time is reduced. The carbon dioxide may cause a little discomfort for a short time.

·       You will be alone in the room during the scan; however, the technologist can see, hear and speak with you at all times.

·       For pediatric patients, a parent may be allowed in the room with their child to help reduce fear and provide comfort. The parent will be required to wear a lead apron to prevent radiation exposure.

Who interprets the results and how do I get them?

A radiologist skilled in CT scanning will review and interpret the CT findings and will send a detailed report to your primary care or referring doctor, who will give you the results. The radiologist will not discuss the results with you.