What is an anal fissure An anal fissure is a disease caused by a fissure in the skin tissue of the anal canal between the dentate line at the very end of the digestive tract and the skin of the anal verge, which repeatedly does not heal. Early fissures are usually small and fresh, but as the disease progresses the fissures can become larger and deeper and even invade the muscular layer, resulting in chronic ulcers, enlarged anal papillae, sentinel hemorrhoids, and in some cases, subcutaneous fistulas of the anal canal. The cause of anal fissure Constipation and stool holding will make the stool dry and coarse, and when the stool becomes dry and coarse, it will break the skin of the anal canal through the anus to form a fissure, resulting in the exposure of subcutaneous nerve tissue and blood vessels, resulting in pain and bleeding when defecating, and the stimulation of pain and local inflammation can lead to spasm of the internal sphincter, and the pressure of the skin of the anal canal increases when the internal sphincter spasms, which leads to local ischemia of the skin of the anal canal because the local blood circulation is obstructed by the increased pressure This is the main reason why the fissure does not heal easily, and the vicious cycle of pain – spasm – ischemia – ulcer – pain again, which is the main reason, of course, there are other reasons, such as chronic infection, acidic stool stimulation, emotional abnormalities, anatomical defects, etc. Anal fissure is not formed when the skin of the anal canal is cracked, but the fissure repeatedly does not heal before it is called anal fissure. Symptoms of anal fissure 1. Pain is the most important symptom of anal fissure, and its typical process is: pain – relief – peak – relief – pain again. The pain is relieved for a few minutes after the bowel movement, and this period is called the pain interval. After that, the pain is intense due to internal sphincter spasm, which lasts for several minutes or hours until the pain is gradually relieved by muscle relaxation after internal sphincter fatigue. The pain will occur again when the next bowel movement occurs. 2. Blood in the stool, mainly blood dripping during defecation or blood on the stool paper, bright red blood, seldom appearing blood spray-like hemorrhage, blood in the stool may also recur periodically.