Salivary fistula is a condition in which saliva drains to the skin surface of the cheek without ductal system. Facial laceration and surgery are the main causes, with the parotid gland being the most common site. Parotid fistulas are divided into glandular and ductal fistulas depending on the location of the fistula. The clinical manifestations are clear saliva flowing from the cheek fistula, which increases significantly when eating. Parotid fistulas can be examined using plastic tubes inserted into the ductal orifice, methylene blue injection, and parotid angiography. Parotid fistulas can be treated with direct pressure dressing, fistula closure, end-to-end duct anastomosis, ductal rerouting, or parotidectomy if necessary, as appropriate. The parotid gland and its ducts are located subcutaneously in the cheek and are superficial and easily traumatized. The submandibular and sublingual glands are less likely to be traumatized because they are protected by the mandible. The main cause of parotid gland injury is facial laceration. A salivary fistula is when saliva drains to the surface of the skin of the cheek instead of draining into the oral cavity through the duct system. The parotid gland is the most common site and trauma is the main cause. Surgical injury to the parotid gland or its ducts can also lead to the development of salivary fistulas. Septic infection or other diseases may also destroy the gland or ducts and create a salivary fistula, but this is rare. Saliva drains from the wound and interferes with its healing, and epithelial cells grow along the fistula, covering the entire wound and forming a permanent fistula. Clinical manifestations Parotid salivary fistulae can be divided into glandular and ductal fistulae depending on the location of the fistula. The glandular end of the fistula leads to the secretory ducts of one or more glandular lobules. There is often a small amount of clear bright saliva flowing from the fistula, which is rarely cloudy. The salivary outflow increases significantly when eating, chewing, smelling or thinking of tasty foods. The saliva flowing from the ductal orifice in the mouth is still normal. 2. Ductal fistula A salivary fistula that occurs in the ductal segment of the parotid gland. According to the condition of the duct fracture, it can be divided into complete fistula and incomplete fistula. In the former case, all saliva flows to the face through the fistula, and there is no saliva secretion from the duct opening in the mouth; in the latter case, although the duct is ruptured, it is not completely severed, and some saliva still flows into the mouth. The saliva flowing from the fistula is clear and bright, while in cases of co-infection it is cloudy. In complete fistulas, the amount of saliva can be more than 2,000 ml, and the skin around the fistula is irritated by saliva and shows flushing, erosion or eczema. The diagnosis of salivary fistula is not difficult based on the history and clinical manifestations, especially the increased amount of flow during eating and chewing is typical. The effluent is analyzed biochemically and qualitatively, and it contains amylase. In patients with cheek injury, especially longitudinal laceration, it is important to check for damage to the parotid glands, especially the parotid ducts. The method of examination is: 1. Insert a thin plastic tube from the mouth into the parotid duct, if the duct is completely broken, the plastic tube can be seen coming out of the injured area. Squeeze the gland to drain the saliva, then the broken end on the side of the gland can be found. 2, for incomplete duct fracture, with the above method may miss the diagnosis, you can slowly inject 1% methylene blue from the mouth of the parotid duct, carefully observe the injury site, if there is duct damage, then immediately stop the injection, so as not to blue stain the area too large, affecting the determination of the fistula. Treatment In cases of glandular fistula with low salivary secretion, the fresh incision is directly bandaged with pressure. In old cases, the fistula tract and fistula opening are cauterized with an electrocoagulator, the epithelium is destroyed, and pressure bandages are applied, along with the parasympathetic depressant atropine, limiting salivary secretion, and avoiding acidic or irritating foods, most of which can heal. If this fails, fistula closure is required: (1) fistula excision and ligation (2) purse-string suturing, submarine separation and suturing of the skin. Fresh parotid duct fractures can be treated with end-to-end duct anastomosis. If the fracture is close to the oral cavity, a ductal rerouting is possible, i.e., the duct is freed and the opening is moved inside the oral cavity to change the external fistula into an internal fistula. For old catheter injuries that have formed a catheter fistula, it is difficult to make a catheter anastomosis due to fibrous scar adhesions. If the fistula is close to the oral cavity, ductal rerouting is possible. If the fistula is close to the portal and is incomplete, the fistula can be closed. If the parotid duct is completely fistulated and the defect is large and the residual duct is short, neither duct anastomosis nor duct diversion can be performed, oral mucosa or vein graft can be used for duct reconstruction. If there is also extensive and deep local scar tissue, parotid duct ligation can be performed after controlling inflammation so that the gland atrophies on its own. If the gland has chronic inflammation and other surgical methods fail, parotidectomy can be considered.