Virtual Colonoscopy uses computed tomography scans. Another method, which is popularly in practice, is magnetic resonance scans. Advantage of these methods is that they are non-invasive and give better and accurate results.

Polyps of 1 millimeter or less can be removed by Colonoscopy. Sigmoidoscopy is also similar to Colonoscopy, but they examine different parts of the colon. Colonoscopy provides complete examination of the colon while the sigmoidoscopy does not.

Any solid matter is diminished or removed before the colonoscopy procedure begins. Low-diet liquid food is advised by the physicians for about two to three days before colonoscopy. The patient may drink apple juice, lemon-lime soda, sports drink, bouillon, etc. Whole bowel irrigation is carried out a day before colonoscopy. Patient is usually considered to be at home, since he has to use the toilet often. The patient is given sedation during the procedure. Many different compounds such as nitrous oxide is also being researched upon as other alternatives. They obviously have their own advantages as well as disadvantages.

A digital rectal examination is the first step to be carried out. The endoscope is passed to the rectum, and finally to the terminal ileum. The endoscope has a mobile tip and more than one channel for suction, air, light and other instrumentation. At the withdrawal of endoscope, screening is done in order to make sure that no damage or bleeding is occurred. This is done usually after 30 minutes of withdrawal of the endoscope. Lesions are treated with laser light. Cutting with electric wire is also done for biopsy purposes. If bleeding occurs, medications are injected.

After the completion of the procedure, revival time is allowed and the patient is constantly checked and observed. Complete recovery time is about half an hour, or one hour. It should not be considered that the procedure has serious risks and it is a matter of great danger. In fact, there is only about 0.35% of risk for the complications to take place.