• CT colonography is an option, along with colonoscopy, to examine your colon for cancer and other diseases.
• It’s a minimally invasive diagnostic method recommended for patients when colonoscopy may not be advisable.
• Sedation and pain relievers not required.
What is CT colonography (virtual colonscopy)?
Computed tomography (CT) colonography, or virtual colonoscopy, is a minimally invasive test used for examining the large bowel for abnormalities. The scan uses CT to create 2D and 3D images that can help detect colorectal cancer, polyps and other abnormalities in your body. The visual examination extends beyond the colon where radiologists may also detect unsuspected medical problems. Before the scan, a very small flexible tip is placed into the rectum to gently inflate the colon. The risk of perforation of the bowel is very low. CT colonography does not require sedation and you can resume regular activities directly after the exam. If any polyps are found that need removal, they need to be removed through a traditional colonoscopy.
Why is ct colonography recommended?
Colorectal cancer is the second leading cause of cancer death in the United States. Approximately 50,000 people die from colorectal cancer every year and about 140,000 are diagnosed.
The goal of CT colonography is to screen for polyps or cancer in the large intestine and to catch abnormalities when they are small and most treatable. The American Cancer Society (ACS) encourages men and women over the age of 50 to complete a colon screening every five years. Individuals at increased risk or with a family history of colon cancer may start screening at age 40 or younger and may be screened at shorter intervals.
Who is a candidate for CT colonography?
You might be a candidate if:
• Sedation is not recommended for you
• You are on blood thinners
• You have severe breathing problems
• You are elderly, frail or ill
• Your bowels are obstructed
• You have active Crohn’s disease, ulcerative colitis, inflammatory bowel disease or diverticulitis.
How does the procedure work?
A CT study is captured by directing a small dose of radiation to different parts of your body. 2D cross-sectional images of your body are displayed on a monitor. When the
image slices are reassembled by computer software, the result is a very detailed multidimensional view of your body’s interior.
In CT colonography, the computer generates a 3D model of your colon and nearby tissue, which the radiologist uses to view the bowel in a way that simulates traveling through it. 2D images of the inside of the colon and the rest of the abdomen and pelvis are obtained and reviewed at the same time without any additional radiation. This allows for detection of unsuspected medical problems outside the colon.
Results will be sent to your ordering physician who can then discuss the report with you.
What you expect before, during and after the exam?
The day before the examination your diet will be restricted to clear liquids. The night before the exam you will be requested to clean out your colon to remove stool by taking a laxative.
The day of the exam patients you should wear comfortable, loose-fitting clothing. You will be given a gown to wear during the procedure. The technologist positions you on the CT table, usually on your back and then on your stomach. Straps and pillows may be used to help you maintain the correct position and to remain still during the exam.
A very small, flexible tube will be passed two inches into the rectum to allow air to be gently pumped into the colon. The purpose of the gas is to distend the colon as much as possible to eliminate any folds or wrinkles that might hide polyps from the radiologist’s view. Next, the table will move through the scanner. You will be asked to hold your breath for about 15 seconds or less before turning over and lying on your stomach or side for a second pass through the scanner. The tube is removed after the scan is complete. The entire examination is normally completed within 15 minutes. You will be able to resume your usual diet and activities immediately afterward.
See information on sedation and pain management for this procedure.