Other important causes of pleural effusions
| Condition | Clinical features | Pleural fluid characteristics | Special investigations and management |
| Early post-CABG pleural effusion158 | Occur within 30 days of CABG. Left > right. Most small and asymptomatic. Prevalence 89% at 7 days postoperatively | Exudate. Bloody (haematocrit >5%). Often eosinophilic | Only perform diagnostic aspiration if the patient is febrile, complains of pleuritic chest pain or the effusion is very large. Most settle spontaneously |
| Late post-CABG pleural effusion159 | Occur >30 days post-CABG. Left > right. May be large and associated with dyspnoea | Exudate. Clear/yellow. Lymphocytic | Diagnostic aspiration to exclude other causes and confirm the diagnosis. Repeated therapeutic thoracentesis usually successful for symptomatic effusions. |
| Urinothorax160 | Due to obstructive uropathy. Urine tracks through the retroperitoneum to the pleural space. | Pleural fluid creatinine > serum creatinine. Transudate. Low pH | Usually resolves with relief of the renal obstruction |
| Ovarian hyperstimulation syndrome161 | Life-threatening reaction to ovulation induction (hCG or clomiphene). May be pleural effusion alone (usually right sided) or whole syndrome with: massive ascites, renal and hepatic failure, thromboemboli and ARDS | Exudate with both protein and LDH in exudative range | Repeated therapeutic aspirations often required to relieve dyspnoea |
| Lymphoma-related pleural effusion162 | Effusion may be associated with mediastinal lymphadenopathy on CT but often there are no clinical features to distinguish from other causes of pleural effusion | Exudate. Lymphocytic. Positive cytology in around 40%. Chylothorax in around 15% | Pleural fluid flow cytometry and cytogenetics may be useful. Thoracoscopic pleural biopsies are often negative but required to exclude other causes if diagnosis unclear |
ARDS, adult respiratory distress syndrome; CABG, coronary artery bypass graft; hCG, human chorionic gonadotrophin.