What are the symptoms that occur when pleural effusion occurs? Under normal circumstances, our pleural cavity is a complete closed cavity with 13-15 ml of plasma, which plays the role of lubricating the pleura, and along with the strong circulatory transfer function of the pleura, there is normally no excessive fluid collection in the pleural cavity, however, once this balance is disrupted by disease, abnormal fluid collection in the pleural cavity will occur, which is called pleural effusion. The common symptoms of pleural effusion are: 1. Chest pain. Generally, the pain is mostly a tingling sensation at the lesion site and is felt to increase with breathing and coughing. With the gradual increase in the amount of pleural effusion, it may be manifested as a feeling of distension and pain. 2. Coughing. Cough is the second common symptom of pleural effusion, mainly manifested as irritating dry cough. 3.Difficulty in breathing. The main reason is that a large amount of pleural effusion compresses the heart and lungs, which in turn causes the patient to have difficulty in breathing. 4.Fever. Fever is often related to the primary disease causing the pleural effusion, and some patients may have a decrease in body temperature after the reduction of pleural effusion. What tests should be done when these symptoms appear? For patients with suspected pleural effusion, from the doctor’s point of view, it is important to clarify the basic situation of the effusion, especially the nature of the effusion, on the one hand, and more importantly, to find the cause of the effusion, which is the basis for the next step of treatment. In addition to basic physical examination, imaging is a commonly used means to diagnose and evaluate pleural effusion. Compared with invasive operations such as thoracentesis and closed chest drainage mentioned later, imaging does not cause trauma, has a higher safety profile, and will be more convenient for patients. Commonly used tests include: 1, X-ray chest film, the examination is fast and convenient, the cost is low, is the most basic imaging means. 2, CT chest. 2, chest CT. CT has certain advantages for the diagnosis of pleural effusion, such as high sensitivity, a small amount of pleural effusion or limited wrapped effusion can be detected on CT, at the same time, CT can also determine some causes of effusion, such as tumors, lung inflammation and other manifestations, while some features of effusion under CT can also be used to help determine the nature of effusion. 3.Ultrasound examination of the chest. Ultrasonography is free of radioactive radiation, easy to operate, and can be used as a means to locate the site of thoracic puncture. How to clarify the cause of pleural effusion? In addition to a series of imaging examinations, direct acquisition of pleural effusion is the most important way to obtain a clear nature, and the main means is thoracentesis and aspiration. On the basis of the nature of the effusion, combined with the patient’s symptoms, disease history, physical examination and imaging findings, the cause of the pleural effusion should be determined. At the same time, for the highly suspected primary diseases, there are also tests for these diseases that need to be performed simultaneously, for example, if tuberculosis is suspected, evidence of tuberculosis needs to be sought, and if tumor is suspected, further investigation is also needed. What is the next step if the cause cannot be identified by laboratory tests? Due to the specificity, complexity, and rarity of certain diseases, it is not possible to identify the cause of the disease 100% through our common tests. The experience of clinicians and the results of ancillary tests are the basic means to explore the cause of effusion. Disease diagnosis is like a police officer solving a case, peeling back the cocoon and drawing out the threads, as if we have been playing a cat and mouse game with the disease hidden behind the scenes, finding some traces is often not easy, some tests may need to be performed several times, some more risky invasive tests may be used in some segments, all of which take time and require the understanding and cooperation of patients and their families. Sometimes, pleural effusion is only one of the symptomatic manifestations of a disease, such as systemic lupus erythematosus, a disease that can affect multiple organs throughout the body, including the manifestation of pleural effusion, so in this case, it cannot be limited to just the part of pleural effusion, but requires a global vision and overall judgment. In some cases, after repeated screening, no other systemic diseases are ever found, but there is always an obvious presence of pleural effusion, we may recommend the patient to undergo pleural biopsy, but of course, such an examination is highly invasive and risky.