Anal fissure is a rupture of the squamous epithelium in the anal canal forming a prismatic fissure or ulcer, which in severe cases can reach deep into the muscular layer. Anal fissures occur most often in young and middle-aged adults, in patients with constipation, and in women during pregnancy and childbirth. The majority of fissures occur in the posterior midline of the anal canal, while some occur in the anterior midline or lateral aspect of the anal canal. The pathogenesis of anal fissures may be due to periodic pain and sphincter spasm caused by local ischemia. It often manifests as periodic, severe, knife-like pain. The pain begins during defecation and continues for several hours until the spasm is slowly released. In general, initial anal fissures can be gradually relieved and healed by adjusting the stool while using topical medication, while old anal fissures often need to be treated with the help of surgery and other methods. The skin of the anal canal is superficially damaged and the tissue around the wound is basically normal; Stage II anal fissure: also called simple anal fissure. The anal canal has formed ulcerative fissures, but there are no comorbidities, no anal papillary hypertrophy, sentinel hemorrhoids and subcutaneous fistulae, etc.; Stage III anal fissures: i.e., old anal fissures, which generally refers to anal fissure triad, but also includes references such as quadruad or quintuad. The manifestation is that the fissure is old ulcer, combined with anal papillary hypertrophy and sentinel hemorrhoids, or accompanied by subcutaneous fistula and anal saphenous inflammation. Treatment of anal fissures 1. Treatment of early anal fissures includes some simple methods as follows: use of laxatives, sitz baths after defecation, and topical application of decay and renewal cream, including local use of glyceryl nitrate or calcium channel blockers. 2. Old anal fissures can be treated with anal dilation or surgery, which is indicated if conservative treatment is ineffective. Surgical results are very effective. Preoperative assessment of sphincter tension is not difficult for specialists, and mastering the degree of sphincter incision is the key to surgical efficacy. Dilation is a relatively conservative treatment that can be performed under local anesthesia, and first- and second-stage anal fissures are often treated with a single dilation for significant symptomatic relief.