An anal fistula is an infected tube that connects the rectum to the skin around the anus, also known as anorectal fistula. The inner mouth is often located near the dentate line and the outer mouth is located on the perianal skin, and the fistula does not heal over the years. The main symptom is the constant flow of pus and blood from the sores on the skin around the anus, just like a broken house that often leaks water, so our ancestors named the disease fistula. The fistula is a tube with two interchangeable sores inside and outside the human body, which can leak secretions and pus from the body to the outside, and a serious anal fistula can see feces flowing out, just like a rat stealing feces hidden inside the sore, which can harm people from time to time, so it is imaginatively called “fecal rat”. The company’s main goal is to provide a comprehensive range of products and services to the public. As mentioned earlier, anal fistula is a sequel to perianorectal abscess, so perianorectal abscess is the root cause of anal fistula. The main reasons why abscesses fail to heal after breaking or incision and eventually form fistulas are: ① Perianorectal abscesses break or incise mostly outside the anus and pus flows from the external opening, but the primary infection is mostly in the anal sinus. The anal sinus is then the portal of secondary infection, which is repeatedly infected and forms fistula tracts. ②Fistula tracts mostly pass between the anal sphincter, and because the sphincter is often constantly contracting and diastolic, it compresses the fistula tract, which affects the elimination of pus and makes it easy to store pus infection and difficult to heal. ③ There is a certain pressure in the rectum, which will rectal infectious substances such as feces, gas, can often constantly enter the fistula from the inner mouth, stimulate the cavity wall, secondary to infection by the outer mouth, is also the cause of fistula. ④After the perianorectal abscess breaks down, the pus is discharged, the pus cavity gradually shrinks, the external rupture and incision also shrink, and the cavity wall forms a hard duct wall with proliferation of connective tissue, and thus cannot be closed naturally. The fistula tract is curved, or has sinuses or branches, which cause poor drainage, retention of pus, and repeated infection, resulting in a fistula that does not heal easily. Therefore, anal fistula can only be cured by surgical removal of the fistula orifice, and so far it cannot be cured by non-surgical methods.