I. Definition of anal fissure Anal fissure is a small ulcer in the skin layer of the anal canal below the dentate line, which is oriented parallel to the longitudinal axis of the anal canal, 0.5~25px long, shuttle-shaped or oval-shaped, with severe pain and difficult healing. Anal fissure is a unique anal disease with its unique site of predilection and unique clinical manifestations; it is neither an atopic nor a nonspecific inflammatory ulcer, much less a trauma-induced wound. Second, the pathogenesis of anal fissure Modern concepts suggest that high sphincter tone induced poor blood supply to the posterior midline of the anal canal is the etiology of primary anal fissure. The essence of anal fissure is an ischemic ulcer. Stage 1 (acute stage): superficial longitudinal fissure of the anal canal skin, with neat and fresh wound edges, obvious tenderness and elasticity of the wound surface. Stage 2 (chronic stage): history of recurrent attacks, irregularity of the trabecular margin, thickening, poor elasticity, purplish-red ulcer base, or purulent secretions, and obvious congestion of the surrounding mucosa. Stage 3 (complication formation stage): ulcers with hard edges, purple-red base and purulent secretions, may be combined with sinus tracts or fistulas, sentinel hemorrhoids, anal papillomegaly, etc., generally known as the “triad” of anal fissure. The timing and sequence of these comorbidities and pathological changes associated with anal fissures are not regular, and one or two or all of them may appear. For acute anal fissures, dietary adjustment and personal hygiene can relieve the symptoms of anal fissures and promote fissure healing. Hard stools can aggravate anal fissures and prevent fissures from healing, so avoiding hard stools can help anal fissures heal. It is recommended to increase the dietary fiber content in food, such as 25~30g per day for adults. 2. Topical drugs, oral drugs and injectable drugs 3. Anal dilation (2) Surgical treatment Internal sphincterotomy Open internal sphincterotomy Closed subcutaneous internal sphincterotomy Lateral sphincterotomy Anal fissure excision Gabriel method Longitudinal transverse suture Modified longitudinal transverse suture Anal fissure excision, anal canal “Y-V” plication