What causes recurring pleural effusion?

Causes of Recurring Pleural Effusion

The most common causes of recurring pleural effusion are heart failure (29%), malignancy (26%), pneumonia (16%), tuberculosis (6%), post-surgery (4%), pericardial diseases (4%), and cirrhosis (3%), with treatment directed at the underlying cause. 1

Primary Causes by Classification

Transudative Effusions

• Heart failure accounts for more than 80% of transudative pleural effusions and is the leading cause of bilateral effusions 2, 1
• Liver cirrhosis (hepatic hydrothorax) accounts for approximately 10% of transudative effusions 2, 1
• End-stage renal failure can cause transudative effusions due to fluid overload 1
• Hypoalbuminemia, nephrotic syndrome, and atelectasis are less common causes 2

Exudative Effusions

• Malignancy, particularly lung cancer, is a leading cause of exudative pleural effusions, followed by breast cancer and lymphoma 2, 1
• Parapneumonic effusions (pneumonia-related) are common and may require drainage if complicated 2, 3
• Tuberculosis causes approximately 6% of pleural effusions and should be considered in undiagnosed cases 2, 1
• Pulmonary embolism can cause exudative effusions and should be reconsidered in persistently undiagnosed cases 2, 1
• Autoimmune conditions: rheumatoid arthritis (occurs in 5% of patients) and systemic lupus erythematosus (affects up to 50% of patients during disease course) 2, 1
• Asbestos exposure can cause benign asbestos pleural effusions, typically within the first two decades after exposure 2

Special Populations

HIV Patients

• In HIV-infected patients, the leading causes of pleural effusion are Kaposi's sarcoma (33%), parapneumonic effusions (28%), and tuberculosis (14%) 2, 1
• Other causes include Pneumocystis pneumonia (10%) and lymphoma (7%) 2

Refractory Effusions

• Heart failure-related effusions that persist despite maximal medical therapy may require pleural interventions 2
• Hepatic hydrothorax that is refractory to medical management may require repeated thoracentesis or consideration of transjugular intrahepatic portosystemic shunt (TIPS) 4
• Malignant effusions often recur and may require indwelling pleural catheters or pleurodesis 2

Diagnostic Considerations

• Differentiation between transudates and exudates using Light's criteria is the first key step in diagnosis 2
• Light's criteria have high sensitivity (98%) but moderate specificity (72%) for identifying exudates 2
• Misclassification of cardiac and liver transudates as exudates occurs in 25-30% of cases 2, 1
• When heart failure is suspected but Light's criteria suggest an exudate, a serum-effusion albumin gradient >1.2 g/dL can reclassify the effusion as a transudate 2
• N-terminal pro-brain natriuretic peptide (NT-BNP) levels >1500 μg/mL in serum or pleural fluid accurately diagnose heart failure as the cause 2

Management Approach for Persistent Undiagnosed Effusions

• Reconsider pulmonary embolism and tuberculosis as they are amenable to specific treatment 2, 1
• A positive tuberculin skin test with an exudative lymphocytic effusion may justify empirical antituberculous therapy 2
• For recurrent heart failure-related effusions refractory to medical treatment, repeated thoracentesis is the first-line approach 2, 4
• Consider indwelling pleural catheters for patients requiring frequent thoracenteses (three or more) 2
• For hepatic hydrothorax, repeated thoracenteses may be performed while planning definitive management 4

Treatment Considerations

• Most transudates can be successfully treated with diuretics, addressing the underlying cause 2
• Complicated parapneumonic effusions (pH <7.2) require prompt drainage and possibly intrapleural fibrinolytics 3
• For refractory heart failure effusions, the European Respiratory Society recommends repeat pleural aspiration before considering other interventions 2
• Indwelling pleural catheters may provide palliation of symptoms and reduced hospital stays in selected patients 2
• For hepatic hydrothorax, indwelling pleural catheters should generally be avoided due to infection risk, particularly in transplant candidates 4

By identifying and treating the underlying cause while providing appropriate symptomatic management, recurring pleural effusions can be effectively controlled in most patients.