1. Clinical features: (1) male incidence is significantly higher than female incidence (5:1); (2) prevalence in young adults (21-40 years old); (3) prevalence at symmetrical points in the posterior midline of the anus; (4) recurrent complex anal fistulas are more common; (5) duration of disease is 1-5 years; (6) high recurrence rate; (7) low natural healing rate; (8) may be accompanied by diseases such as enteritis and diabetes that reduce the body’s resistance rate; 2. 2. Symptoms (1) Early symptoms: usually a history of perianal rectal infection or abscess. (2) repeated discharge of purulent secretions; (3) pain: fistulas are often painless without inflammation, only localized swelling and discomfort, aggravated by walking, if the external opening is closed and the fistula accumulates pus, there is pain, aggravated by defecation. (4) Pruritus: the skin around the anus often feels itchy when stimulated by secretions. (5) Systemic symptoms: There are often no systemic symptoms, and those with deep and recurrent inflammation and abscesses are thin, anemic, and constipated.