An anorectal fistula is an abnormal tube formed in the anal canal or rectum that is connected to the skin around the anus for pathological reasons, and is called anal fistula, also known as hemorrhoid fistula or anal leakage in Chinese medicine. The fistula is characterized by an internal fistula located in the anal sinus, which passes through the perianal tissue, and an external fistula located in the perianal skin, from which purulent secretions often flow, resulting in local swelling and pain due to the closure of the external fistula, followed by pus re-rupture at or near the original external fistula, and so on repeatedly. The majority of anal fistulas develop from perianal abscesses around the anorectum. When the abscess breaks down or is incised and drained, the thick fluid flows out, the mass dissipates and becomes a fistula, the main manifestations of which are as follows The new generation of anal fistula flow more pus, pus thick, smell, yellow, and then gradually reduced, sometimes not, into white, thin quality. If there is a sudden increase in pus, it means that a new pus cavity is created. Sometimes the external mouth is temporarily closed, the flow of pus stops, the body temperature rises, local swelling, and abscesses are formed again. The closed external opening is then punctured, or another new external opening is formed, and pus overflow occurs again. In cases of coarse internal and external fistulae, sometimes fecal gas flows from the external orifice. In submucosal fistulas, the ulceration is mostly in the anal verge or sinus, and pus often flows from the anus. In single-port internal fistulas, pus is mixed with blood and often flows from the anus, and sometimes a few streaks of blood are visible in the feces. In the case of nodular anal fistula, the pus is more dilute, yellowish, rice slop-like, and can have cheese-like necrotic material. 2, pain: if the fistula drainage is smooth, generally do not feel pain, only feel the external mouth area swelling discomfort, walking aggravated. If the outer mouth is closed, or if the drainage is poor and pus accumulates, there can be local swelling or throbbing pain. If the internal opening is large and feces enters the fistula, there is pain, which is aggravated when defecating. Single-port internal fistulas commonly cause burning discomfort in the lower rectum and anus, and pain is felt during defecation. Submucosal fistulas often cause anal cramping and pain that radiates to the lumbosacral region. 3, itching: the skin around the anus feels moist and itchy due to the frequent stimulation of secretions, and even causes anal eczema, skin papules, or epidermal peeling, long-term stimulation can lead to thickening of the skin moss-like changes. 4, poor defecation: general anal fistula does not affect defecation. The high complexity of anal fistula or horseshoe fistula, due to chronic inflammatory stimulation, causing the anal canal rectal ring fibrosis, or fistula around the anal canal, forming a semi-annular fibrous ring, affecting the anal sphincter diastolic, can appear defecation is not smooth. 5, systemic symptoms: general anal fistula often no systemic symptoms, but complex anal fistula and tuberculous anal fistula, because of the long period of disease, some with decades, often appear body wasting, anemia, constipation and defecation difficulties. In case of acute inflammation and re-infection with pus, systemic symptoms of abscess will appear.