The skin of the anal canal is split longitudinally in its entirety, or a poke-shaped ulcer is formed. The main clinical manifestations are pain, blood in the stool, and constipation. Most of the anal fissures occur on the posterior side of the anal canal, and a few on the anterior side. Staging: 1. Acute (fresh) anal fissure: short duration, fresh fissure, shallow bottom and neat edges. 2.Chronic (old) anal fissure: long duration, recurrent, with pyknotic ulcer formation and thick, hard edges. The upper end of the fissure often has anal sinusitis and anal papillomatous hyperplasia, and the lower end has fissured hemorrhoids or submerged fistulas. Clinical symptoms: 1. Periodic pain: pain during defecation, relieved after defecation, followed by spasmodic pain in the sphincter. 2. 2. Blood in the stool: blood dripping from the stool or blood on the paper, bright red blood, more or less amount. Constipation: Constipation is often the initial cause of anal fissure, and later patients are often afraid of defecation because of the pain, the stool will stay in the intestinal tract for a long time will further dry, and the dry stool will make the fissure bigger and more painful, forming a vicious circle. 4, wet and itchy: fissure secretions out of the anus and dampness, stimulating the perianal skin and cause itching, and over time can be followed by perianal eczema. Prevention: 1, pay attention to the diet, do not overwork, do not drink, and eat less spicy stimulating food. 2, to prevent dry stools, eat more fresh fruit, crude fiber can stimulate gastrointestinal motility, conducive to defecation. When defecating should not struggle, so as not to tear the skin of the anal canal. 3, warm water bath after the stool, to accelerate perianal blood circulation.