• At the beginning of your appointment, you will be brought to an assessment area, where the doctor and/or nurse will explain the procedure and answer your questions. At that time, you’ll be asked to sign a consent form, giving your permission to have the procedure performed. You will also meet with an anesthesiologist who will be responsible for sedating you during your procedure and watching your breathing and heart rate. You will be asked to change into a hospital gown and remove your eyeglasses and contact lenses.
• You will then be taken into a procedure room, where you will lie on your left side in a comfortable position, and will be given medication to make you sleepy and relaxed through an injection into a vein. The doctor will then pass the colonoscope through the anus and into the rectum, and advance it through the colon. This examination generally takes fifteen to sixty minutes. Depending on what your doctor sees, he or she may also obtain a biopsy or remove polyps found at this time. Removed tissue and polyps are sent to the laboratory for analysis. These additional steps do not usually cause discomfort.
• During the procedure, you may experience some abdominal cramping and pressure from the air that is introduced into your colon. This is normal, and will pass quickly. You may be asked to change your position during the examination, and will be assisted by a nurse.

To learn more view this video: