What are the characteristics and symptoms of anal fistula? Anal fistulas can develop at any age, including infants and young children, and are more common in young adults and more common in males than females, but infants and young children have a tendency to heal themselves as their organism and intestinal immune function improve. In adults, fistula is an infectious disease in which bacteria invade from a weak or broken mucous membrane in the anus (usually the anal fossa) and spread around and outside the anus to form an anal fistula. It is a disease in which the rectum of the anal canal communicates with the skin around the anus and a pathological canal appears, consisting of a primary internal opening, a secondary external opening, and a fistula canal, usually formed after a perianal abscess has broken down. The clinical manifestations of anal fistula are recurrent localized pus flow, long-lasting closure, painful accumulation of pus when the external opening is closed, or fever, etc. During the examination, strips can be palpated or probed into the anus. The fistula, once formed, has very little chance of healing itself, and if it is not treated in a timely manner, recurrent attacks can easily complicate the fistula and affect the quality of life in addition to the pain associated with the disease, such as frequent pus spillage and contamination of clothing; local skin is often stimulated, which can lead to eczema and itching, affecting work, study and life. The treatment of anal fistula is a worldwide problem. The traditional anal fistula surgery, after a long period of clinical practice, has a stable efficacy. At present, some minimally invasive techniques mainly refer to those that can preserve the anal sphincter to the maximum extent and prevent postoperative functional decline. LIFT (Ligation of Inter-Sphincter Fistula), which was first proposed by British experts, is a surgical concept that can preserve the anal sphincter intact, and was later improved and promoted worldwide to form the current minimally invasive procedure, which has the advantage of not cutting the anal sphincter and perfectly protecting the anal function, but is less effective for complex anal fistulas. Some other procedures using biomaterials, such as biogel and anal fistula plugs, can also completely preserve the sphincter, but they cannot be used as the clinical treatment of choice because of their unstable clinical efficacy and high price. In recent years, a new type of treatment has emerged (laser ablation closure of anal fistula), which has been clinically used in some European countries for more than 5 years with an overall efficiency of about 80%, including the treatment of some special types of anal fistula (such as Crohn’s disease anal fistula). At present, our hospital has introduced this new technology and has been the first to successfully carry out it in Shanghai, being one of the few hospitals in China to carry out this new technology. As a new procedure that preserves the sphincter muscle intact, it avoids postoperative damage to anal function, is mildly painful, significantly shortens hospital stays, and cures anal fistulas while protecting anal function. The technique is simple and is performed with a very thin laser guide wire that enters the patient’s body through the external opening of the fistula and passes through the fistula to the internal opening, simultaneously emitting the laser in a circular pattern to cauterize and ablate the epithelial tissue, retreating while cauterizing and closing the fistula. This technique does not damage the sphincter, avoids the risk of incontinence, is repeatable, and can be combined with other forms of treatment, making it a promising minimally invasive tool. Of course, the technique is currently only suitable for some types of fistulas, and indications need to be mastered to obtain the best results. In conclusion, the treatment of anal fistula is still a hot spot, and the concept of functional protection and individualized treatment will be the future trend.