A pleural effusion is a build-up of fluid in the space between the lungs and the chest wall. This space is called the pleural space. Thoracentesis is a procedure to remove fluid from this area.

There are two types of thoracentesis:

  • Therapeutic thoracentesis—to relieve the symptoms of fluid accumulation
  • Diagnostic thoracentesis—to test for the cause of the fluid build-up

There is always a small amount of fluid in the pleural space. The fluid helps to lubricate the area. When too much fluid builds up in this space, it can make it difficult to breathe.

Your doctor may want to test some of the fluid after removing it. The build-up of fluid can be a symptom of diseases or disorders, such as: