The full name of anal fistula should be anorectal fistula, which is commonly known as fistula, and is also called anal leakage in Chinese medicine. Anal fistula is a common anorectal disease, accounting for about 10% of anorectal morbidity in China, and is common in young adults between 20 and 40 years of age, as well as in infants and children. Its effects on the human body are repeated perianal infections, swelling and pain, and scarring of the perianal tissue. I. Formation of anal fistula Why can’t the perianal abscess heal itself and form an anal fistula after ulceration, it is generally believed that there are the following reasons: 1. The perianal abscess breaks or incisions are mostly outside the anus, and the pus flows out from the external mouth, but the primary infection is mostly in the anal sinus. The anal sinus is the gateway to continue the infection, because the anal sinus opens upward and opens in the rectal cavity, bacteria and intestinal contents can enter the pus cavity through the anal sinus, causing repeated infections and forming fistulae. 2, the fistula passage between the anal sphincter, because the sphincter often constantly contract and diastolic, affecting the discharge of pus, easy to store pus infection and difficult to heal. 3. After the abscess breaks down, the pus is discharged, the pus cavity gradually shrinks, and the cavity wall forms a hard duct wall with proliferation of connective tissue, which cannot heal. 4, the fistula is bent, or has branches, poor drainage, repeated infection, resulting in fistula does not heal. The fistula is accompanied by a history of painful ulceration and pus flow next to the anus in varying degrees, and after the formation of the fistula, the painful pus flow next to the anus will recur from time to time, and if the pus flows poorly, the local and general symptoms of acute purulent infection will appear, such as local redness, swelling and pain in the anus and increased body temperature, but these symptoms will gradually decrease as the pus breaks out again. Another clinical manifestation of anal fistula is the presence of hard masses in the anal area. In addition, long-term pus irritation can lead to perianal dermatitis or eczema, causing itching in the anus. If the fistula is not healed for a long time, it will also cause difficulty in defecation, anemia, body wasting, mental depression and neurological weakness. The only way to finally solve anal fistula is surgery. Like paranal abscess, anal fistula differs from infections in other parts of the body because it occurs near the anorectum and has a fixed source of infection in the anal or rectal cavity, i.e., the internal opening, while the lesion is located in the anal sphincter, and the diastole and contraction of the sphincter affect the discharge of pus. Therefore, there is no possibility of self-healing for anal fistulas and paranal abscesses once they occur, regardless of their severity, and medication will only alleviate the symptoms, and the only way to achieve clinical cure is through surgical (including wire) treatment. There have been many attempts to treat fistulas and perianal abscesses with methods other than surgery, but they have all ended in failure, to say the least, and so far no non-surgical methods have been found to cure them. The purpose of fistula surgery is to cut open the fistula, remove the internal opening, completely eliminate the source of infection, allow the fistula to drain freely, and allow the new granulation tissue to grow upward from the bottom of the wound and gradually fill in the wound.