Mucus in the anus is mostly caused by anorectal diseases, anal fistula, internal hemorrhoids, perianal abscess and so on may appear such symptoms. First, anal fistula, especially with an internal mouth, fistula, external mouth of the typical anal fistula, outside the rectum and anus in addition to the formation of a channel, so that the mucus in the rectum and anus tube, feces in the case of the patient is not conscious of the outflow, mucus around the anus, and most often accompanied by a bad smell; Second, internal hemorrhoids, internal hemorrhoids development to the third and fourth, hemorrhoid nuclei and their enlargement prolapse outside the anus, need to be manually returned to the or can not be returned to the hemorrhoidal nucleus surface Mucous membrane secretion, as well as due to hemorrhoids stay caused by the anus, can not be completely occluded mucus exudation, etc., will cause mucus at the anal opening of the symptom; three, perianal abscess, abscess will be mucus outflow after rupture, will also cause such a symptom. In addition, the anal sphincter relaxation, will cause the anal opening of the atresia is not strict, rectal anal tube mucus will also seep out to the anus.