Hemoptysis (hemoptysis) is bleeding from the respiratory organs below the larynx that is discharged from the mouth by coughing action Hemoptysis must first be differentiated from oral, pharyngeal, and nasal bleeding Oral and pharyngeal bleeding are easily observed as localized foci of bleeding. Nasal bleeding mostly comes from the anterior nostril, and it is often easier to diagnose the bleeding foci found in the anterior and inferior part of the nasal septum. Sometimes the bleeding from the posterior part of the nasal cavity is large and can be misdiagnosed as hemoptysis. The diagnosis can be confirmed if the blood is seen to flow down the pharyngeal wall from the posterior nostril by nasopharyngoscopy. The former often has a history of tuberculosis, bronchiectasis, lung cancer, heart disease, etc. Before bleeding, there is a cough, throat itching and chest tightness, and the blood is bright red, mixed with foamy sputum, usually without tarry stools; the latter often has a history of peptic ulcer, cirrhosis, etc. Before bleeding, there is upper abdominal discomfort, nausea and vomiting, etc. The blood is brown-black or dark red, sometimes bright red, mixed with food residue and gastric juice. It is mixed with food residue and gastric juice and has tarry stools, which may persist for several days after the vomiting has stopped. There are different definitions for estimating the amount of hemoptysis. Massive hemoptysis usually refers to hemoptysis of more than 600-800 ml or more than 300 ml per hemoptysis within 24 h. Small hemoptysis refers to less than 100 ml per hemoptysis; moderate hemoptysis refers to 100-300 ml per hemoptysis. Despite the application of various tests, 5%-15% of patients with hemoptysis have unknown causes of hemoptysis, called occult hemoptysis. Some occult hemoptysis may be caused by lesions such as tracheal and bronchial non-specific ulcers, varicose veins, early adenomas, small bronchial stones and minor bronchial dilatation. 1. Bronchial diseases commonly include bronchiectasis (tuberculous or non-tuberculous), chronic bronchitis, endobronchial tuberculosis, and bronchial carcinoma (primary lung cancer). Less common are benign bronchial tumors, endobronchial stones, bronchial non-specific ulcers, etc. 2. Lung diseases commonly include tuberculosis, pneumonia, lung abscess, etc. Less common are pulmonary stasis, pulmonary infarction, malignant tumor metastasis, pulmonary cyst, pulmonary fungal disease, pulmonary schistosomiasis, etc. Tuberculosis is one of the most common causes of hemoptysis. 3. Cardiovascular disease is more commonly associated with hemoptysis due to mitral stenosis. Hemoptysis can also occur in certain congenital heart diseases such as atrial septal defect and patent ductus arteriosus, which cause pulmonary hypertension. 4. Other blood diseases (such as thrombocytopenic purpura, leukemia, hemophilia, etc.); acute infectious diseases (such as pulmonary hemorrhagic leptospirosis, epidemic hemorrhagic fever, etc.); connective tissue diseases (such as polyarteritis nodosa); endometriosis, etc.