Pleural effusion means abnormal accumulation of fluid in the pleural cavity between the chest wall and lungs.
Excess fluid presses the lung and can make breathing harder.
The causes of a pleural effusion are varied.
It can for example be caused by the heart’s decreased ability to pump blood, a lung infection, liver or kidney disease, or even some medications.
The reason for a pleural effusion is not necessarily obvious from your scan.