Patients have a small amount of coughing up blood, more common in the respiratory tract diseases, as well as cardiovascular system diseases, specifically as follows: First, respiratory diseases: which respiratory diseases are mainly caused by decreased immunity, the patient by staphylococcus aureus, Klebsiella, tuberculosis mycobacterium, fungi, as well as other parasitic infections, which causes inflammation of the respiratory tract. At this time, the pathogens will destroy the mucosa of the respiratory tract, causing congestion, edema and inflammatory secretions, but also can make the airway wall of the capillary rupture, thus coughing up a small amount of blood symptoms. In addition, traumatic injury to the lungs can lead to rupture of blood vessels in the lung mucosa, resulting in a small amount of bleeding. This symptom can be seen in malignant tumors of lungs, such as early alveolar cell carcinoma and bronchial lung cancer, which cause mild rupture of cancer and bleeding. Cardiovascular system diseases: cardiovascular system diseases are mainly common in pulmonary edema caused by left heart failure due to various reasons, which may also cause rupture of pulmonary blood vessels, coughing up blood and pink foamy sputum.