1.Causes of rhinorrhea 1.1.Local factors Rhinorrhea belongs to a disease symptom, which is divided into local causes and systemic causes according to the nature of the disease causing rhinorrhea, which can be further divided into common causes and uncommon causes according to the incidence. Among the local causes, nasal bleeding caused by finger picking is a common cause of nasal bleeding, mostly seen in children. Nasal mucosal injury due to topical nasal medication use, such as corticosteroids and antihistamines can result in smaller nasal bleeds in 17 ~23% of patients using this medication. Incorrect nasal drug use can also cause nasal bleeding, if the drug is sprayed to the lateral wall of the nasal cavity can reduce the effect of the drug on the nasal septum thus reducing the incidence of non-bleeding, also studies have shown that the left and right handedness in the citation of nasal sprays is associated with the laterality of the nasal bleeding site, therefore patients should be advised to spray the right nasal cavity with the left hand and the left nasal cavity with the right hand. How trauma to the nasal bone and septum can cause severe nasal bleeding. Dry nasal mucosa in winter can increase the incidence of rhinorrhea. Nasal septal deviation or perforation (which often causes dryness of nasal mucosa), bacterial or viral rhinosinusitis and nasal tumor can cause rhinorrhea. 1.2. Systemic factors Retrospective studies show that 45% of patients hospitalized for rhinorrhea have systemic disorders, which are potential causes of rhinorrhea. Nasal bleeding can occur in people with coagulation disorders, including genetic defects such as hemophilia, acquired coagulation disorders such as liver and kidney disease, anticoagulant use, hematologic malignancies, and low-dose aspirin can slightly increase the incidence of rhinorrhea. A randomized controlled trial showed a 19.1% incidence of nosebleeds in women taking low-dose aspirin for cardiovascular disease prevention compared with 16.7% in a control group taking placebo. Hypertension can cause rhinorrhea, but this theory is also currently controversial. One cross-sectional study showed no correlation between hypertension and rhinorrhea. Some studies have also suggested that blood pressure is elevated in patients with rhinorrhea. However, it is difficult to determine that hypertension is the cause of a nosebleed when it occurs because the anxiety that many patients experience during a nosebleed can lead to an increase in blood pressure. Hereditary hemorrhagic capillary dilation is another genetic disorder that predisposes to rhinorrhea. 2 .Treatment options for rhinorrhea 2.1 .Compression Compression is used for milder anterior nasal bleeding. Most anterior nasal bleeding is self-limiting, and most anterior nasal bleeding can be stopped by compressing Little`s area. The correct compression should be done by squeezing the front of both nasal wings toward the nasal septum with both thumbs or index fingers, and the compression should be continued for 20 minutes (as in Figure 1) [15]. Anterior nasal bleeding can also be constricted by filling the anterior part of the nasal septum with a cotton pad containing a decongestant for 15 minutes. In addition to compression, topical spraying of hydroxymetazoline is also useful. The results of a study showed that topical application of hydroxyzoline in patients with rhinorrhea met in the emergency room could be the cessation of bleeding in 65% of patients [17]. 2.2, cautery Erosion or cautery can be chosen when nasal bleeding cannot be controlled by compression and application of local constricting agents. Chemical cautery with silver nitrate or trichloroacetic acid can be applied after the application of anesthetics and decongestants to the nasal cavity. Chemical cautery is safe and effective, and it can effectively control more than half of the bleeding that cannot be controlled with decongestants [17]. Chemical cautery on only one side reduces the risk of medically induced nasal septal perforation. Chemical cautery can be applied in milder active bleeding or after active bleeding has been controlled and the bleeding vessel is clearly identified. If chemical cautery is to be applied uniformly on both sides of the septum, the cautery must be applied 4 C 6 weeks apart to allow for mucosal growth and repair. 2.3, Caulking: Anterior nasal cavity caulking is used for bleeding in the little area that cannot be controlled by the above methods. Conventional fillers are non-biodegradable materials such as oil gauze, Merocel expanded sponge and Rhino gel. These fillings need to be removed after 1-3 days of placement. Clinical randomized controlled trials have shown that 60-80% of nasal bleeding that is not treated with decongestants can be controlled by caulking. There is no difference in the control of bleeding between Merocel expanding sponges and Rhino gel, but Rhino gel is easier to insert and withdraw. Posterior nasal tamponade is the treatment of choice for posterior nasal bleeding. Posterior nasal tamponade is required for bleeding from the pterygopalatine artery, and approximately 70% of posterior nasal bleeding can be controlled by posterior nasal tamponade. Complications of nasal caulking include nasal septal hematoma, abscess due to caulking injury, sinusitis, and pressure necrosis, and rare major complications include sepsis, cardiac arrhythmias, hypoxia, and death. When retaining nasal fillings, it is often necessary to apply topical antibacterial ointment application to the surface of the filling bulb or to treat with oral antibiotics to avoid toxic shock syndrome. There are no data on the incidence of this complication in patients with nasal fillings, but in those with nasal fillings after nasal surgery, the incidence is 0.0165%. It is not clear whether toxic shock syndrome is associated with nasal filling, as it still occurs after sinus surgery without filling. Since this complication is rare, there is also a lack of data to suggest that the incidence of this complication can be reduced when antibiotics are applied. Because of the potential for asphyxia, patients with anterior or posterior nostril fillings routinely require oxygen saturation testing in the hospital. The application of balloon tamponade for nasal bleeding is also an option, where the front end of the balloon is inserted along the base of the nasal cavity and the balloon is inflated with sterile water or air until the nasal bleeding stops. coles et al [23] compared saline and sterile water and found that the application of saline to inflate the balloon was able to maintain the balloon for a longer period of time with constant pressure. For posterior nasal bleeding, a double balloon device is applied, with the posterior balloon passing through the nasopharynx and sealing the posterior nostril to fill and compress the bleeding point, and the anterior balloon inflated in the anterior nasal cavity to prevent the posterior balloon from receding. In the absence of a dedicated balloon, the Foley catheter can also be used as a substitute. The patient can be placed in any position during balloon tamponade, and it is not affected by the position for critically ill and comatose patients. It is suitable for comatose, difficult to open the mouth, old and frail patients and uncooperative children. The complications of balloon tamponade include saline aspiration, pressure gangrene, perforation and infection. 3. Surgical ligation and interventional treatment Surgical ligation and interventional treatment are used for intractable nasal bleeding. When nasal bleeding is sometimes difficult to control by traditional hemostatic methods, it is called persistent nasal bleeding. Surgical ligation or endonasal endoscopic erosion of the internal maxillary artery, external carotid artery and pterygopalatine artery is required for intractable rhinorrhea. Interventionalists can embolize the terminal branches of the internal maxillary and pterygopalatine arteries to treat posterior nasal hemorrhage. Sokoloff et al. (1974) first reported the use of embolization to treat nasal hemorrhage, and Merland et al. (1980) reported a 97% success rate for embolization of severe nasal hemorrhage, so this technique is widely accepted. Although the effectiveness of this technique is comparable to surgical treatment, there is a risk of serious complications, and the complications reported by different scholars vary considerably, which may be related to the embolization technique. The incidence was 2/47. Serious complications include stroke, facial palsy, blindness, and renal damage from contrast application, and the incidence of these complications is approximately 4%. Minor complications such as facial pain, facial edema, headache, confusion, abnormal sensation, chewing pain, numbness and hematoma have an incidence of about 10%. And the success rate of treatment is 80-90%. Embolization therapy is rarely applied with the anterior and posterior sieve arteries because of the risk of inserting the catheter into the internal carotid artery or the ophthalmic artery, with a higher risk of stroke and blindness. Therefore, most otolaryngologists use external ligation of the anterior and posterior sieve arteries, separating them from the orbital periosteum along the superior orbital surface, approximately 2.5 cm from the anterior orbital rim. The vascular nerve sheath of the anterior sieve artery can be seen extending medially at the frontal sieve suture and is ligated or bipolar cautery is applied to the portion of the anterior and posterior sieve artery in the frame before it exits the frame. If hemostasis is not achieved, the posterior septal artery can be ligated by continuing to enter posteriorly for approximately 6 mm. Studies have shown that surgical ligation of the pterygopalatine artery has a success rate comparable to or better than interventional treatment. With modern nasal endoscopic techniques, ligation can be performed in 30-60 minutes and complications in angiography are avoided with nasal endoscopic ligation techniques. However, general anesthesia is required. Ligation of the pterygopalatine artery allows the patient to be discharged earlier and shortens the length of stay.