Effusion (Fluid in Pleural Space)

In an erect film there is loss of the costophrenic angle with dense shadowing extending a variable distance up the lung. The lateral part is higher, creating the meniscus appearance. On supine films posterior pooling of fluid gives a less specific haziness to the lung field.

Click on the x-rays to enlarge.

Fig 1: Right effusion Fig 2: Left effusion

What are the different types of effusion?

The different types are:

  • Transudates – protein concentration <30g/L

Due to: Cardiac failure, constrictive pericarditis, fluid overload, nephrotic syndrome, liver failure, Meigs’ syndrome

  • Exudates – protein content >30g/L

Due to: Pneumonia, TB, pulmonary embolism (PE), lung cancer, mesothelioma, pancreatitis, connective tissue disease

  • Blood i.e. haemothorax in trauma
  • Pus i.e. empyema