Stages of anal fistula formation 1. Infection and inflammation of the anal saphenous fossa and anal flap are limited to local inflammation at first, and if not treated in time, the inflammation can spread to the perianal area. 2. Inflammation gradually spreads and forms perianal fistula; if the inflammation cannot be controlled, it may invade into the tissue gap with low resistance to disease. 3.Inflammation invading into the tissue gap with low disease resistance will form perianorectal abscess, such as improper treatment, tissue necrosis pus expansion, aggravating the disease. 4, perianal abscesses break down on their own or by incision and drainage improperly resulting in repeated infections, recurring episodes, can not heal themselves over time, and become fistulas. 3 common symptoms after the development of anal fistula 1, pain: in the absence of inflammation is painless, but when swollen and inflamed due to infection or pus is not timely, can cause pain. 2, itching: due to the constant stimulation of the perianal skin by pus, it often feels itchy, fibrous tissue proliferation and thickening, and sometimes eczema is formed. 3, systemic symptoms: in the acute inflammatory phase and repeated attacks of complex anal fistula, there can be varying degrees of fever, or accompanied by long-term chronic wasting symptoms such as wasting, anemia and weakness. The 5 bad habits that lead to anal fistula 1, reading a book and newspaper while going to the toilet. 2, diarrhea and constipation. 3, long-term alcohol consumption or spicy food people. 4, standing or sitting for a long time. 5, irregular life.