A pleural effusion is a buildup 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 2 types of thoracentesis:

  • Therapeutic thoracentesis—to relieve the symptoms of fluid buildup
  • Diagnostic thoracentesis—to test for the cause of the fluid buildup

Possible Complications

Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:

  • Collapsed lung
  • Fluid building up again
  • Bleeding
  • Infection
  • Damage to the lung, liver, or spleen

Factors that may increase the risk of complications include:

Factors that may increase the risk of complications include:

  • A history of lung surgery
  • A long-term, irreversible lung disease, such as emphysema or poorly controlled asthma
  • Smoking
  • Anything affecting normal blood clotting



This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Pleural Fluid Aspiration; Pleural Tap)


American Lung Association 

American Thoracic Society 


The Canadian Institutes of Health Information 

The Lung Association 


How to Do Thoracentesis. The Merck Manual Professional Edition website. Available at: Updated October 2016. Accessed February 12, 2018.

Thoracentesis. American Thoracic Society. Available at: Updated February 2016. Accessed February 12, 2018.

Thoracentesis. Johns Hopkins Medicine website. Available at:,P07761. Accessed February 12, 2018.

Thoracentesis. National Heart Lung and Blood Institute website. Available at: Accessed February 12, 2018.

6/3/2011 DynaMed Plus Systematic Literature Surveillance  : Mills E, Eyawo O, et al. Smoking cessation reduces postoperative complications: A systematic review and meta-analysis. Am J Med. 2011;124(2):144-154.