Pleural effusion is a medical condition where fluid accumulates in the pleural cavity which surrounds the lungs, making it hard to breathe.
Pleural effusion can result from reasons such as:
- lung cancer
- infection such as pneumonia or tuberculosis
- autoimmune disease such as lupus erythematosus
- heart failure
- bleeding, often due to chest trauma (hemothorax)
- low oncotic pressure of the blood plasma
- lymphatic obstruction
- accidental infusion of fluids
In states of excess accumulation, pleural fluid can be sampled and evaluated to determine what disease state may be causing it. The evaluation consists of
- Gram stain and culture - identifies bacterial infections
- cell count and differential - differentiates exudative from transudative effusions
- cytology - identifies cancer cells, may also identify some infective organisms
- chemical composition including protein, lactate dehydrogenase, amylase, pH and glucose - differentiates exudative from transudative effusions
- other tests as suggested by the clinical situation - lipids, fungal culture, viral culture, specific immunoglobulins