Pleural effusion, also known as “pleural fluid”, is very common in clinical practice. Before determining how to deal with pleural effusion, it is important to understand that pleural effusion can be caused by a variety of etiologies, and different etiologies can be treated in completely different ways. I. What are the causes of pleural effusion? What are the main treatment principles? Pleural effusion is not one disease, but a clinical manifestation of many different diseases. When a doctor encounters a patient with pleural effusion, he or she usually has to extract the pleural fluid for laboratory tests to determine whether it is “exudate” or “leaky fluid”. The top 3 common causes of exudate in our country are tuberculous pleurisy, metastatic pleural cancer, and pneumonic effusion. At a glance, it is clear that their management principles are completely different: tuberculous pleurisy is treated with anti-tuberculosis drugs, pleural metastatic carcinoma is treated with chemotherapy and symptom relief, and pneumonic effusion is treated with antibacterial drugs (anti-infective). Common causes of leaking fluid include cardiac insufficiency (heart failure), renal insufficiency, and hypoproteinemia. The principle of treatment is mainly to deal with the primary disease, the primary disease is well controlled, the pleural fluid naturally absorbed and improved, generally not for the pleural fluid itself for special treatment. 2.FAQ 1.Can a small amount of pleural effusion be absorbed by itself? The key to this question depends on what the cause of the pleural effusion is. Small amounts of fluid caused by tuberculosis and pneumonia can be absorbed on their own after medication and do not necessarily require pleural fluid extraction. Leaky fluid caused by various reasons generally does not require pleural fluid extraction and can be absorbed on its own after treatment of the original disease. 2.What is the amount of pleural fluid that needs to be pumped? It depends on the situation. The first time pleural fluid is pumped, the purpose is to conduct laboratory tests to clarify the cause of the disease, even if a small amount is extracted. If the cause is clear, but the amount of pleural fluid is relatively large and causes symptoms of chest tightness and dyspnea, it is necessary to pump pleural fluid to relieve the symptoms. 3.Pleural fluid repeatedly appears after pumping, is it necessary to pump again in this case? It also depends on the different causes of the disease. For example, in tuberculous pleurisy, under active medication, if pleural fluid recurs after pumping, it needs to be pumped again. Effusion due to tumors is more difficult to control and often requires multiple pleural fluid aspirations to relieve symptoms. Leaky fluid from various causes (e.g., heart failure) often recurs as the condition changes, in which case the primary cause should still be treated aggressively and pleural fluid aspiration is generally not recommended.