Complex anal fistulas are more serious. Because the opening, course, and location of the fistula cannot be determined, it is a relatively difficult fistula or perianal disease to treat. Complex fistulas are at high risk of recurrence if the fistula is not completely treated during surgery or if all fistulas have not been healed. Thus, the seriousness of the disease lies in the uncertainty of treatment. Even if a small branch is missed during surgery, it may result in postoperative recurrence, which has a greater impact on the patient and may lead to 2-3 surgeries or even multiple surgeries.