An anal fissure is a chronic fissure in which the entire skin of the anal canal splits and forms a chronic ulcer. It is one of the common anal diseases, mostly seen in young and middle-aged women, and the majority of anal fissures are located in the posterior median line of the anal canal. Although common, the lack of awareness of the disease means that patients may not realize that they may have anal fissures even when they present with typical clinical manifestations. The following clinical manifestations can help in the diagnosis of anal fissure. Pain Pain is the most important symptom of anal fissure and is characterized by a cyclical nature. When defecating, you immediately feel burning pain or cutting pain in the anus, which is called stool pain; a few minutes after defecation, the pain can be relieved, which is called intermittent period, and then, due to spasmodic contraction of the anal sphincter, the pain is sharp again. It can last for half an hour to several hours, making the patient restless and very painful, which is clinically called sphincter contracture pain. The pain gradually stops when the sphincter is tired. The pain occurs again when defecating again. This is called the anal fissure pain cycle. Constipation Constipation is one of the causes of anal fissures, and is also a sequel to anal fissures. When constipation expels dry and hard feces, it may tear the anal skin and form anal fissures. After the occurrence of anal fissures, patients are afraid to defecate for fear of pain during defecation, thus often causing constipation. Constipation can aggravate the fissure, forming a vicious circle. Blood in the stool A small amount of blood is often seen on the surface of the stool or on the stool paper, or drops of fresh blood, but heavy bleeding is rare. 4. Anal fissure triad The longitudinal fissure of the anal canal, with a pouch-like skin pendant at the lower end and an enlarged anal papilla at the upper end, is called the anal fissure triad. Based on the typical manifestations of anal fissures, especially the characteristics of periodic anal pain, constipation and bleeding, it is not difficult to diagnose anal fissures. However, in order to improve the accuracy of diagnosis and prevent misdiagnosis and misdiagnosis, patients with anal fissure should also preferably go to a regular hospital for professional examination.