Virtual Colonoscopy
Virtual Colonoscopy (VC), also referred to as CT colonography, is a safe and effective exam used for colon polyp screening. The entire colon lining can be seen with VC. A computed tomography (CT) scan creates a picture of the inside of your colon. VC allows the doctor to see your colon and to take a limited look outside the colon for abnormalities of the abdomen and pelvis.
The main purpose of this exam is to screen for growths (polyps) in the lining of the large intestine (colon and rectum). The American Cancer Society (ACS) screening guidelines recommend Virtual Colonoscopy at five year intervals for all adults age 50 and over at average risk for colon disease.
If a large polyp or growth is found in your colon, a standard colonoscopy may be needed to remove the polyp. "Large" polyps are those 1 cm (about 3/8 inch) or greater and should be removed because they have a higher chance of turning into cancer.
A growth of this size is present in less than 5 percent of all patients. If a growth of this size is discovered a standard colonoscopy can be arranged.
Smaller polyps, 6 mm to 9 mm (about 1/3-1/4 inch), can also be removed by standard colonoscopy. There is some research to suggest that patients with less than three smaller (6-9mm) polyps can be monitored with short term VC follow up. However, the current American Cancer Society recommendations are to have these polyps removed.
Preparing for your VC exam
To prepare for this exam, you must clean your colon. Follow the instructions in your bowel prep kit that includes laxatives and the special clear liquid diet. If you feel you cannot complete the bowel prep, tell the CT technologist before your exam.
Take all prescribed medicines as directed with sips of water before your VC (if you have diabetes, see the information below). Do not eat or drink after midnight on the night before the exam. Ask your doctor if you have any questions before your exam.
If you have diabetes
If you have diabetes, please call your doctor to discuss how your diabetes medicine (oral diabetes pills and/or insulin) doses should change before this procedure.
Test your blood sugar more often the day before this test. Also check your blood sugar the morning of your test. If your blood sugar level is low (less than 70 mg/dl) or if you have symptoms, eat some glucose tablets or drink four ounces of a clear liquid with sugar.
Always recheck your blood sugar level to make sure it stays above 70. We may still be able to do the procedure, unless you need to eat solid food to keep your blood sugar at a normal level. If the blood sugar ever gets too high or too low and you can't bring it back to normal, call your primary care or diabetes doctor.
When to arrive for your VC exam
You do not need to have a family member or friend drive you to the VC exam, as you will not be given any medicine that will make you sleepy.
During the VC exam
The VC exam most often takes 15 minutes or less to complete. Neither pain or sedation medicine nor an IV is needed for this exam. You will be asked to change into a hospital gown for the exam. You will be taken to a CT exam room where you will lie on the CT exam table.
A small tube will be gently placed a very short distance into your rectum (this feeling is like having a digital rectal exam). Gas will be placed slowly into your colon. The exam should not be painful, though you may have some abdominal fullness, discomfort or cramping. You may feel the urge to have a bowel movement. Pictures are taken of your abdomen and pelvis while you are lying on your back and then on your stomach. In each position, you will be asked to hold your breath for about 10 seconds while the CT scanner takes pictures.
After the VC exam
You may resume your normal diet after the exam. If a polyp is found that should be removed, your standard colonoscopy will be set up at a later date. |
