Perianal underwear can be seen traces of blood, the emergence of this situation should not be nervous should be analyzed for its causes: first, ask whether there is a history of hitting or falling, or foreign objects inserted into the anorectal injury history. If there is such a history, you can usually see cracks around the anus, and sometimes there will be blood flow. Second, if a woman should also exclude whether in the menstrual period, because after the menstrual period is closer to the anus, sometimes can also lead to the anus at the blood. Third, if the patient has mixed hemorrhoids, anal fissure or rectal polyps, it can also lead to stimulation of blood vessels under the mucous membrane when defecating, thus leading to blood. So there are many reasons why there are traces of blood in the underwear around the anus, you should actively go to the hospital, if necessary, you can carry out rectal fingerprinting to clarify the diagnosis.