A GP will refer a patient presenting with a pleural effusion to a Consultant Chest Physician at their local hospital for investigations in establishing the cause of the pleural effusion and also the extent of the effusion. It is important to make an accurate diagnosis. The prognosis and treatment are different between malignant and non malignant (benign) effusions. It is also important to note that even with cancer up to 50% of effusions are benign.
The Chest Consultant will note whether there is any weight loss which can be a sign of underlying malignancy such as cancer, additionally consideration will be given to the patient’s smoking history, and any rheumatoid changes in the hands. Some effusions can also cause reduced movement on the side of the chest where the effusion is. An effusion can cause differences in the way the lungs ‘sound’, for example a chest when tapped will sound dull and breath sounds will be reduced. The chest may not expand properly.
It is often difficult for Doctors to diagnosis an effusion purely from examination. Therefore an imaging test, usually a simple chest x-ray may be carried out. Effusions will show up on the x-ray once the fluid builds up has reached about 300 millilitres. Prior to that, it may be difficult to spot the fluid build up from a simple examination.
If the cause of the effusion is known no further tests will be undertaken. However as previously mentioned a pleural effusion may be the first sign of an underlying condition such as lung cancer or mesothelioma. Further tests may then be necessary which may include lung tests, blood tests and taking a sample of the fluid from the pleura to examine in the laboratory.