The main manifestations of anal fissure are pain and blood in the stool, both of which are closely related to defecation. The first is pain. The pain is caused by the dilatation of the anal canal during defecation, which may disappear for a short time after defecation, and then it may be followed by severe pain due to sphincter spasm, which may last until the next defecation. Another manifestation is blood in the stool, which is also caused by fecal dilatation of the anal canal, causing small blood vessels in the fissure to tear and bleed. Sometimes the bleeding is irregular, sometimes it is present, sometimes it is not, and usually the amount of bleeding is relatively small, sometimes it is fresh blood in the stool, sometimes it is blood in the stool, sometimes it is blood in the stool paper, and the blood can be mixed with a small amount of mucus. If there is periodic pain in the anus along with irregular blood in the stool, it should be considered an anal fissure.