Diagnosis of Empyema
An empyema is usually suspected when a person with severe pneumonia does not improve with treatment, and they start to show some of the above symptoms.
If the patient is coughing up mucus, a sample of this should be taken to be inspected under a microscope. The type of bacteria causing the infection is identified so the most effective antibiotics can be given.

A blood sample will also be taken, to count the number of white blood cells and other markers of infection.

An X-ray or ultrasound scan will show whether there is a collection of fluid building up around the lungs and how much there is. Often a CT scan may also be used to give a more detailed assessment.