A pleural effusion is an abnormal amount of fluid around the lung. Pleural effusions can result from many medical conditions. Most pleural effusions are not serious by themselves, but some require treatment to avoid problems.
The pleura is a thin membrane that lines the surface of the lungs and the inside of the chest wall outside the lungs. In pleural effusions, fluid accumulates in the space between the layers of pleura. Normally, only teaspoons of watery fluid are present in the pleural space, allowing the lungs to move smoothly within the chest cavity during breathing.
Numerous medical conditions can cause pleural effusions. Some of the more common causes are
Excessive fluid may accumulate because the body does not handle fluid properly (such as in congestive heart failure, or kidney and liver disease). The fluid in pleural effusions also may result from inflammation, such as in pneumonia, autoimmune disease, and many other conditions.
Pleural effusions often cause no symptoms. Symptoms are more likely when a pleural effusion is moderate or large-sized, or if inflammation is present. Symptoms of pleural effusions may include:
Because pleural effusions are usually caused by underlying medical conditions, symptoms of these conditions are also often present.