Some small sinus tracts can heal themselves, for example, those with fresh trauma and no obvious infection will gradually heal, but some must be treated with intervention to heal, for example, the sinus tract of anal fistula is small but because it has an internal fistula opening there is a constant flow of intestinal fluid into it, bacteria will multiply and the sinus tract will not heal, the infected tissue of the sinus tract must be removed from the internal fistula opening before it can heal. If the abdominal gastrointestinal surgery is done and there is a gastrointestinal leak, there is digestive fluid flowing down the sinus tract in the abdominal wall, and the sinus tract can only grow if the digestive fluid stops. Other sinus tracts such as tumor implantation and metastasis sinus tracts are not self-healing, and if the nutritional status is poor, the sinus tract will also be slow to heal.