There are many reasons why there are fissures at the anal opening, the first one, the more common is the dry stool, dry feces is easy to damage the skin of the anal canal, thus leading to fissures. The second, there may be a foreign body injury, such as foreign body invasion of the rectum of the anal canal thus leading to fissure, especially in the anterior and posterior anus is more common, long-term constipation and injury, so that the back wall of the anal canal to withstand the pressure is relatively large, especially in the defecation, the front wall of the anal canal, the back wall of the anal canal to withstand the pressure of the pressure is relatively large, the pressure of the external anal sphincter of the anal canal superficial part of the blood supply is insufficient, all lead to fissures in the anus mouth. If previously performed hemorrhoidectomy or chemical injury, will lead to local weakness, which will lead to the occurrence of anal fissure. So don’t be nervous about the anal fissure, you should actively go to the anorectal clinic, you can perform visualization, if necessary, you can perform rectal diagnosis or insert anoscopy to clarify the diagnosis.