There are four main possibilities: 1, hemorrhoids, when the hemorrhoid vein pressure increases, can rupture on its own caused by bleeding, at this time should be given Yunnan Baiyao sandblasting in the wound and pressure bandage, to stop bleeding, warm water bath, local application of hemorrhoid cream or hemorrhoid suppository symptomatic treatment, if the bleeding volume should be immediately to the regular hospital anorectal surgery or general surgery for surgical treatment. 2, anal fissure, long-term constipation caused by stool The typical symptoms are anal bleeding and severe anal pain, which should be treated by surgery once diagnosed. 3, benign rectal diseases, such as adenoma or polyp, when adenoma or polyp mucosal vessels rupture, blood in the stool can occur, and the bleeding can stop on its own. 4, malignant rectal tumors, there may be no obvious clinical manifestations in the early stage, but when the disease progresses to advanced stage, it can appear Blood in stool or black stool with diarrhea or unformed stool.