Pleural Effusion Health Article

Causes of exudative pleural effusions

A wide range of conditions may be the cause of an exudative pleural effusion:

• Pleural tumors account for up to 40% of one-sided pleural effusions. They may arise in the pleura itself (mesothelioma), or from other sites, notably the lung.
• Tuberculosis in the lungs may produce a long-lasting exudative pleural effusion.
• Pneumonia affects about three million persons each year, and four of every ten patients will develop pleural effusion. If effective treatment is not provided, an extensive effusion can form that is very difficult to treat.
• Patients with any of a wide range of infections by a virus, fungus, or parasite that involve the lungs may have pleural effusion.
• Up to half of all patients who develop blood clots in their lungs (pulmonary embolism) will have pleural effusion, and this sometimes is the only sign of embolism.
• Connective tissue diseases, including rheumatoid arthritis, lupus, and Sjögren's syndrome may be complicated by pleural effusion.
• Patients with disease of the liver or pancreas may have an exudative effusion, and the same is true for any patient who undergoes extensive abdominal surgery. About 30% of patients who undergo heart surgery will develop an effusion.
• Injury to the chest may produce pleural effusion in the form of either hemothorax or chylothorax.

Symptoms

The key symptom of a pleural effusion is shortness of breath. Fluid filling the pleural space makes it hard for the lungs to fully expand, causing the patient to take many breaths so as to get enough oxygen. When the parietal pleura is irritated, the patient may have mild pain that quickly passes or, sometimes, a sharp, stabbing pleuritic type of pain. Some patients will have a dry cough. Occasionally a patient will have no symptoms at all. This is more likely when the effusion results from recent abdominal surgery, cancer, or tuberculosis. Tapping on the chest will show that the usual crisp sounds have become dull, and on listening with a stethoscope the normal breath sounds are muted. If the pleura is inflamed, there may be a scratchy sound called a "pleural friction rub."