Usually, perianal abscesses will form anal fistulas in about 3 months after surgery, but the exact time depends on the severity of the patient’s condition, the surgical method and the recovery after surgery. A perianal abscess is an acute purulent infection of the perianal rectal tissue or the surrounding space, which is treated by incision and drainage of the abscess, but 30-70% of patients in the clinic will have problems such as dead space at the anal canal and poor drainage after surgery, and usually an anal fistula will gradually form in about 3 months, requiring another anal fistulotomy or fistula ligature. It is important to note that not all perianal abscesses will form an anal fistula after surgery, and if you choose perianal abscess excision and drainage with a phase I ligature, the chance of forming an anal fistula after surgery will be less than 30%. It is recommended that patients follow the doctor’s instructions to change medication and maintain perianal hygiene after surgery, and if symptoms such as local redness, pain and pus occur after surgery, they should go to the anorectal department of the hospital for consultation in a timely manner, and cooperate with the doctor for medication or surgery after a clear diagnosis.