Pleural effusion occurs when fluid builds up in the space between the lung and the chest wall. This can happen for many different reasons, including pneumonia or complications from heart, liver, or kidney disease. Another reason could be as a side effect from cancer.

What is the most common cause of pleural effusion?

Transudative pleural effusion is caused by fluid leaking into the pleural space. This is from increased pressure in the blood vessels or a low blood protein count. Heart failure is the most common cause.

How does pleural effusion develop?

How does pleural effusion develop? The pleura creates too much fluid when it's irritated, inflamed, or infected. This fluid accumulates in the chest cavity outside the lung, causing what's known as a pleural effusion.