Causes of pleural effusion
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Causes of Pleural Effusion
Pleural effusion, the accumulation of excess fluid in the pleural cavity, is a common medical condition with a variety of underlying causes. Understanding these causes is crucial for accurate diagnosis and effective treatment.
Common Causes of Pleural Effusion
Congestive Heart Failure and Cirrhosis
Congestive heart failure (CHF) is one of the leading causes of pleural effusion. In CHF, the heart's inability to pump blood effectively leads to fluid accumulation in the lungs, which can overflow into the pleural space 12. Similarly, cirrhosis with ascites can cause pleural effusion due to the movement of fluid from the peritoneal cavity into the pleural cavity through diaphragmatic pores .
Malignancy
Malignant pleural effusions are frequently caused by cancers such as lung carcinoma, breast carcinoma, and lymphomas 1210. Lung cancer is the most common cause of malignant pleural effusion, followed by breast cancer . The presence of cancer cells in the pleural fluid, detected through cytological examination, confirms the diagnosis .
Infections
Infections, particularly pneumonia, are significant causes of pleural effusion. Approximately 40% of patients with pneumonia develop pleural effusion, which can progress to empyema if not treated promptly . Tuberculosis is another notable infectious cause, especially in regions with high TB incidence .
Pulmonary Embolism
Pulmonary embolism (PE) can lead to pleural effusion due to increased pressure in the pulmonary arteries, causing fluid to leak into the pleural space 12. About 75% of patients with PE may develop pleural effusion .
Less Common Causes
Abdominal and Retroperitoneal Diseases
Certain abdominal and retroperitoneal conditions, such as pancreatitis, ovarian tumors, and hydronephrosis, can cause pleural effusion without direct extension into the chest. This is often due to overburdening or interruption of lymphatic drainage .
Multiple Etiologies
In some cases, pleural effusion may result from multiple concurrent causes. For instance, a patient might have both heart failure and a malignancy contributing to the effusion. Identifying all contributing factors is essential for optimal treatment 89.
Diagnostic Approach
Transudative vs. Exudative Effusions
Differentiating between transudative and exudative pleural effusions is a critical step in diagnosis. Transudative effusions are typically caused by systemic factors like CHF and cirrhosis, whereas exudative effusions result from local factors such as infections and malignancies. This distinction is made using pleural fluid analysis, measuring protein and lactate dehydrogenase (LDH) levels 25.
Advanced Diagnostic Techniques
Recent advancements include the use of biomarkers like N-terminal pro-brain natriuretic peptide (NT-proBNP) to identify heart failure-related effusions and thoracoscopic pleural biopsies for more accurate diagnosis of malignancies and infections .
Conclusion
Pleural effusion can arise from a wide range of conditions, including heart failure, malignancies, infections, and abdominal diseases. Accurate diagnosis, often involving differentiation between transudative and exudative effusions, is essential for effective treatment. Understanding the underlying causes and employing advanced diagnostic techniques can significantly improve patient outcomes.
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