A colonoscopy requires careful bowel preparation to ensure the colon is completely clean for clear visualization of the lining. Preparation typically involves following a clear liquid diet for one or two days before the examination and taking strong laxative medications (bowel prep) the evening before and the morning of the procedure. The colonoscopy is often performed under moderate sedation or deep sedation to help the patient relax and minimize discomfort. The colonoscope is gently inserted through the rectum and slowly advanced through the colon. The physician introduces air or carbon dioxide through the scope to inflate the colon and improve visualization. The camera at the tip of the scope transmits live images to a monitor, allowing the physician to examine the lining carefully as the scope is slowly withdrawn. If polyps or suspicious areas are found, the physician can remove them using small instruments passed through a channel in the scope (polypectomy) or take small tissue samples (biopsy) to be sent to a laboratory for examination. The procedure itself usually takes 30 to 60 minutes.