Coughing up blood mostly refers to hemoptysis, which is bleeding from the throat and any part of the respiratory tract below the larynx that is clucked out through the mouth. A small amount of hemoptysis is sometimes manifested only as blood in the sputum, while in major hemoptysis blood gushes out from the mouth and nose, often obstructing the airway and causing death by asphyxiation. Generally, the causes of hemoptysis are mainly considered to be respiratory diseases, such as tuberculosis, bronchodilatation, bronchitis, lung abscess, lung cancer, pneumonia and so on. Some causes are also due to circulatory diseases, such as rheumatic heart disease, mitral stenosis, hypertensive heart disease, pulmonary hypertension, aortic aneurysm, pulmonary infarction and pulmonary arteriovenous fistula. Other causes are due to chest trauma, contusion, rib fracture, leukemia, aplastic anemia, chronic renal failure, and uremia. When patients have hemoptysis, they should seek medical treatment in time to clarify the cause of the disease and then give effective treatment.