- The illness recured after a normal colonoscopy report within one year that was provided by this hospital or a grade first class teaching hospital, include polyp of colon (less than 3mm,the number of less than 5) patients who taked therapeutic endoscopy and recurrenced within one year; or those that get a normal colonoscopy report in this hospital or a grade first class teaching hospital before screening but have a history of bowel preparation, should be chosen when next attack.