Condition	Potential causes of the pleural effusion
History
Abdominal surgical procedures	Postoperative pleural effusion, subphrenic abscess, pulmonary embolism
Alcohol abuse or pancreatic disease	Pancreatic effusion
Artificial pneumothorax therapy	Tuberculous empyema, pyothorax-associated lymphoma, trapped lung
Asbestos exposure	Mesothelioma, benign asbestos pleural effusion
Cancer	Malignancy
Cardiac surgery or myocardial injury	Pleural effusion secondary to coronary artery bypass graft surgery or Dressler’s syndrome
Chronic hemodialysis	Heart failure, uremic pleuritis
Cirrhosis	Hepatic hydrothorax, spontaneous bacterial empyema
Childbirth	Postpartum pleural effusion
Esophageal dilatation or endoscopy	Pleural effusion secondary to esophageal perforation
Human immunodeficiency virus infection	Pneumonia, tuberculosis, primary effusion lymphoma, Kaposi sarcoma
Medication use	Medication-induced pleural disease
Remote inflammatory pleural process	Trapped lung
Rheumatoid arthritis	Rheumatoid pleuritis, pseudochylothorax
Superovulation with gonadotrophins	Pleural effusion secondary to ovarian hyperstimulation syndrome
Systemic lupus erythematosus	Lupus pleuritis, pneumonia, pulmonary embolism
Trauma	Hemothorax, chylothorax, duropleural fistula
Signs
Ascites	Hepatic hydrothorax, ovarian cancer, Meigs’ syndrome
Dyspnea on exertion, orthopnea, peripheral edema, elevated jugular venous pressure	Heart failure, constrictive pericarditis
Pericardial friction rub	Pericarditis
Unilateral lower extremity swelling	Pulmonary embolism
Yellowish nails, lymphedema	Pleural effusion secondary to yellow nail syndrome*
Symptoms
Fever	Pneumonia, empyema, tuberculosis
Hemoptysis	Lung cancer, pulmonary embolism, tuberculosis
Weight loss	Malignancy, tuberculosis, anaerobic bacterial pneumonia