There is always stool on the anal opening, mainly because of the following. First, there are hemorrhoids at the anal opening, mixed hemorrhoids in defecation will be discharged with the activity of the anal sphincter muscle, hemorrhoids on the stool in the wipe will not wipe clean and cause. Second, because there are anal fissure, perianal abscess, anal fistula and other diseases, will be formed at the anal opening of the rectum through the channel outside the anus. When the anus is stimulated by stool when the channel will have a small amount of fecal discharge, thus causing. Third, it is usually bad defecation habits or congenital anal sphincter contraction, which leads to the anus can not be well controlled, involuntary bowel movement out. Fourth, it is mainly because the anal opening is infected by bacteria and viruses, which leads to the continuous reproduction of bacteria and secretion of stool-like substances.