- You will have an anoscopy. An anoscopy is an examination of the rectum in which a small tube is inserted into the anus to screen, diagnose, and evaluate problems of the anus and anal canal. To perform this test, acetic acid is placed on the anus and the area is looked at for pre-cancerous areas using a colposcope (an instrument that magnifies the cells of the cervix and vagina to allow for direct observation and study of the living tissue). The acetic acid is used to help the pre-cancerous areas show up better. If you have an abnormal test result, you will be referred to a colorectal specialist so that you can be seen and then treated according to the standard of care.