Normal people’s pleura actually has two layers, divided into the structure close to the chest wall, that is, the wall pleura on the opposite side of the rib cage, and close to the internal organs of the lungs of this layer of dirty side pleura, the liquid between these two layers of pleura is pleural fluid, so pleural fluid is actually normal people, but the amount of pleural fluid is relatively low, usually in the 5-15mL or so. In the case of an increase in pleural fluid is called pleural effusion, fluid in more cases need to be carried out on it to deal with. The main causes of pleural effusion generally include the following: 1) infections, such as pleurisy of the chest cavity. 2) specific bacterial infections, such as tuberculous pleurisy. 3) malignant diseases, the most common of which are lung and pleural cancers, which can cause a relatively large amount of pleural effusion. The treatment of pleural effusion is mainly through pleural drainage, drainage at the same time for examination to determine which cause of pleural effusion, in order to carry out further treatment.