What you may notice
A pleural effusion is fluid in the space between a lung and the chest wall, rather than inside the breathing tubes. It may cause breathlessness, a dry cough or pain when breathing. A small amount may be found on a scan before symptoms develop.
Fluid outside the lung, in blue
What could cause it?
Heart failure, pneumonia or tuberculosis, cancer, liver or kidney disease and a lung blood clot are among the causes. Breathlessness can also come from asthma, anaemia or heart and lung conditions without an effusion. Examination, chest imaging and sometimes fluid analysis help establish the explanation.
When to contact a doctor
New or worsening breathlessness should be assessed promptly. Severe breathing difficulty, chest pain, blue lips, confusion or collapse is an emergency: call 108. Fever or feeling very unwell with a known effusion also needs urgent review. The amount of fluid on an old report cannot determine whether current breathlessness is safe.
How interventional radiology may help
The underlying condition must be treated. An image-guided needle sample or drain may identify the cause or relieve symptoms in selected patients. Infected or repeatedly returning fluid may need a longer drainage plan with the respiratory team, sometimes including surgery or pleural treatment. Not every small effusion needs drainage.
Further reading: detailed assessment and treatment options
Patient information sources
References are in English.
Educational information, not a diagnosis. The causes listed are examples, not a complete list. Tests and treatment depend on your individual assessment.