A polymerase chain reaction for tuberculous DNA may be done, or adenosine deaminase or interferon gamma levels may also be checked.The most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism. Another common cause is after heart surgery when incompletely drained blood can lead to an inflammatory response that causes exudative pleural fluid. Conditions associated with exudative pleural effusions:
Parapneumonic effusion due to pneumonia
Malignancy (either lung cancer or metastases to the pleura from elsewhere)
Infection (empyema due to bacterial pneumonia)
Trauma
Pulmonary infarction
Pulmonary embolism
Autoimmune disorders
Pancreatitis
Ruptured esophagus (Boerhaaves syndrome)
Rheumatoid pleurisy
Drug-induced lupus

Other/ungrouped
Other causes of pleural effusion include tuberculosis (though stains of pleural fluid are only rarely positive for acid-fast bacilli, this is the most common cause of pleural effusions in some developing countries), autoimmune disease such as systemic lupus erythematosus, bleeding (often due to chest trauma), chylothorax (most commonly caused by trauma), and accidental infusion of fluids. Less common causes include esophageal rupture or pancreatic disease, intra-abdominal abscesses, rheumatoid arthritis, asbestos pleural effusion, mesothelioma, Meigss syndrome (ascites and pleural effusion due to a benign ovarian tumor), and ovarian hyperstimulation syndrome.Pleural effusions may also occur through medical or surgical interventions, including the use of medications (pleural fluid is usually eosinophilic), coronary artery bypass surgery, abdominal surgery, endoscopic variceal sclerotherapy, radiation therapy, liver or lung transplantation, insertion of ventricular shunt as a treatment method of hydrocephalus, and intra- or extravascular insertion of central lines.
Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus arteriosus closes. Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus, blood flow to the lower body can be impaired. This type is most common in adults. It is associated with notching of the ribs (because of collateral circulation), hypertension in the upper extremities, and weak pulses in the lower extremities. Postductal coarctation is most likely the result of the extension of a muscular artery (ductus arteriosus) into an elastic artery (aorta) during fetal life, where the contraction and fibrosis of the ductus arteriosus upon birth subsequently narrows the aortic lumen.Aortic coarctation and aortic stenosis are both forms of aortic narrowing. In terms of word root meanings, the names are not different, but a conventional distinction in their usage allows differentiation of clinical aspects. This spectrum is dichotomized by the idea that aortic coarctation occurs in the aortic arch, at or near the ductus arteriosus, whereas aortic stenosis occurs in the aortic root, at or near the aortic valve. This naturally could present the question of the dividing line between a post valvular stenosis and a preductal coarctation; nonetheless, the dichotomy has a practical use, as most defects are either one or the other. Signs and symptoms
In mild cases, children may show no signs or symptoms at first and their condition may not be diagnosed until later in life.