Categories of pleural effusion aetiologies and their corresponding definitions
| Congestive heart failure |
| Echocardiogram within 1 month or at the time of the procedure documenting one or more of: |
| Decreased systolic ejection fraction (≤45%) and pulmonary oedema on CXR; |
| Diastolic dysfunction and pulmonary oedema on CXR; |
| Moderate-to-severe aortic stenosis (valve area <1 cm), aortic regurgitation, mitral stenosis or mitral regurgitation and pulmonary oedema on CXR; |
| Restrictive and/or constrictive pericardial disease and pulmonary oedema on CXR |
| Severe pulmonary hypertension; |
| Or: |
| Cardiac arrhythmia on ECG and pulmonary oedema on CXR |
| Renal failure |
| Documented nephrotic range proteinuria; or |
| Creatinine >1.5 mg·dL−1; or |
| Ongoing renal replacement therapy |
| Liver failure |
| Documented cirrhosis with ascites; or |
| Acute, fulminant liver failure |
| Pneumonia/infection |
| Ipsilateral infiltrate on CXR and >500 WBCs per mL in fluid or positive fluid culture |
| Multiple benign aetiologies |
| Documentation of more than one of the above aetiologies without one predominant aetiology |
| Malignant |
| Positive pleural fluid cytology or flow cytometry |
| Paramalignant |
| Negative cytology in patient with known cancer localised in the ipsilateral chest and no other potential cause for pleural effusion |
CXR: chest radiography; WBC: white blood cell.