INFO/WWW: Causes of pleural effusion are ususally divided by the effusion`s protein concentration into transudates (<30g/l) and exsudates (>30g/l). Reasons for transudates are e.g. heart failure, liver failure, nephrotic syndrome. Reasons for exsudates are e.g. pneumonia, TB, empyema, lung carcinoma, pleuritis and trauma. A pleural effusion tends to accumulate in the most dependent parts of the pleural cavity - in the erect position these are the posterior costophrenic recesses. A pneumothorax is an accumulation of air in the pleural space. Often spontaneous due to rupture of a plural bleb. Other causes are trauma - also iatrogen CVC lines, asthma, TB, pneumonia and others. Pneumothorax will show as an area devoid of lung.
