The clinical manifestations of anal fissure are: pain in the anus during stool, blood in the stool. Constipation. On examination, the anal opening is extremely sensitive and there is a fissure and ulcer when the anal canal is pulled. If the fissure is just outside the anal verge, the patient will not be in pain, but only during defecation, and the pain is not obvious after defecation. This is because the fissure does not extend beyond the intersphincteric sulcus and does not cause spasm of the internal sphincter during defecation. (The intersphincteric sulcus is approximately in the middle of the anal canal, and a gap between the external and internal sphincters can be palpated during finger examination. Above the intersphincteric sulcus is the internal sphincter, and below the intersphincteric sulcus is the external sphincter.) The typical pain of anal fissure is pain in the anus caused by stool, which is mild during stool and heavy after stool with intermittent periods. The pain during stool is due to direct damage or stimulation of the anal canal fissure by feces, while the pain after stool is caused by spasm of the internal sphincter, which puts the anal canal under tension for a longer period of time, so the pain is intense. Depending on the depth and location of the fissure, the pain time varies from a few minutes to several hours or even longer. If the fissure is small and shallow, and the internal sphincter is not stimulated to spasm during defecation, the pain is only painful during defecation and not obvious after defecation. The bleeding of anal fissures is sporadic and is related to defecation. The amount of bleeding is also related to the size and depth of the fissure and the freshness of the ulcer surface. Anal fissures can occur anywhere in the anal canal, with superficial fissures, limited to the subcutaneous area, often with several fissures present at the same time, with mild pain, little bleeding, significant itching, and no complications such as ulcers, sentinel hemorrhoids, or enlarged anal papillae. Anal fissures should also be differentiated from leukoplakia and syphilitic anal canal ulcers. Fresh anal fissures can be treated conservatively with local medication and oral laxatives, as well as with anal dilation therapy, while old anal fissures require surgery if conservative treatment is not effective. Surgery is also relatively simple, and local anesthesia is sufficient.