The real cause of anal fistulae is an infection of the anal glands. The anal glands usually open at the anorectal junction of the anal sinus, and most of them go outward past the anal sphincter into the perianal space, where they can become infected and form abscesses around the anus, which can form fistulas when they break down. Of course there are some anal fistula patients who do not necessarily have a perianal abscess, this is because it is a chronic infection that is not detected by the patient. So most anal fistulas will have an external opening, an internal opening and a canal that can be repeatedly infected repeatedly to form an abscess-fistula-abscess process. In severe cases, the infection can penetrate through the perianal space to the opposite side or deeper so that a high anal fistula or complex anal fistula is formed. Fistulas must be treated surgically to heal. However, the previous surgical approach had major drawbacks, and usually an incision or excision was performed to remove the fistula. This inevitably involves severing or partially severing the anal sphincter, and in the case of high anal fistulas, possibly severing the levator muscle, which can cause anal incontinence or impairment of anal function. For high anal fistula surgery is now recognized as one of the three major world problems in general surgery. An article from the United States mentioned that 48% of patients with damage to the anal sphincter will have postoperative anal insufficiency, such as postoperative spillage and inability to identify gas and loose stools well. This type of surgery can also be followed by anal agenesis, which is also a cause of postoperative anal insufficiency. Once anal dysfunction occurs after surgery, it cannot be repaired surgically, thus becoming a regret for anal fistula treatment. This type of surgery will also have a disadvantage that is, once the surgery does not remove to the inner mouth of the fistula, so it is easy to recur after the surgery, so the surgeon is prone to enlarge the wound when removing it, which is more likely to cause anal damage.