Colonoscopy is used to visually examine your entire colon and rectum for abnormalities. Colonoscopy is generally considered the procedure of choice for colon cancer screening. During the exam, a colonoscope — a long, flexible tube about the thickness of an adult finger — is inserted into your rectum. A tiny video camera at its tip allows Dr. Dawson to view the inside of your colon.

In some cases during colonoscopy, if a polyp or abnormal tissue is found, Dr. Dawson may remove it at that time. Alternatively, a tissue sample (biopsy) of the polyp may be taken for lab analysis to determine whether subsequent surgical removal of the tissue is needed.

A colonoscopy is relatively painless when performed by an experienced practitioner. You will receive a sedative medication administered intravenously to minimize any discomfort.

During the exam you'll likely lie on your left side. Dr. Davidson inserts the colonoscope into your rectum. Colonoscopes are disinfected between procedures, so the risk of transmission of infection is extremely low. The colonoscope is long enough to allow your doctor to view the entire length of your colon. It contains a fiber-optic light and a channel that allows your doctor to pump air into your colon, inflating it to get a better view of the interior lining. You may feel some abdominal cramping or pressure as the air is introduced.

The colonoscope also contains a tiny video camera at its tip. The camera transmits images to an external monitor so that your doctor can look closely at the inside of your colon. Your doctor can insert instruments through the colonoscope's channel to remove polyps, take tissue samples, inject solutions or destroy (cauterize) tissues.

If a polyp or abnormal tissue is found, Dr. Dawson may choose to remove it with a snare or destroy it with cautery. Or he might take a biopsy or advise surgical removal, depending on the size of the mass.

A colonoscopy exam usually takes about 20 minutes to an hour.