This page was reviewed under our medical and editorial policy by
Chukwuemeka Obiora, MD, Surgical Oncologist.
This page was reviewed on April 7, 2023.
A thoracentesis is a procedure that extracts excess fluid from an area called the pleural space, which is located between your chest wall and lungs. The excess fluid is called a pleural effusion. A pleural effusion could make it harder for you to breathe. It also may cause pain, dry cough and heaviness in the chest. A thoracentesis may help relieve these symptoms as well as diagnose why the extra fluid has accumulated in that area.
There are several reasons why a doctor may perform a thoracentesis. If you have certain types of cancer, including lung cancer, you have a greater chance of developing fluid around the lungs. About 40 percent of lung cancer patients develop a pleural effusion, according to the American Society of Clinical Oncology. Others associated with a pleural effusion include breast and ovarian cancers, mesothelioma and lymphoma.
It’s also possible for cancer to grow in the pleural space between the chest wall and lungs. When it does, it’s called a malignant pleural effusion.
A thoracentesis is one of several options available to treat a pleural effusion. Other options include a catheter and tube thoracostomy.
There are a few ways you can prepare ahead of a thoracentesis.
Your doctor may perform the thoracentesis at a medical office, outpatient center or hospital.
Your doctor may send out any fluid removed for pleural fluid analysis. You also may undergo a chest X-ray right after the thoracentesis to check on your lungs.
When the thoracentesis is completed, your care team will briefly monitor your blood pressure and breathing. You may return to your regular diet and activities at home, with your doctor’s approval. The doctor may ask you to avoid heavy physical activity for a couple of days.
The benefits of a thoracentesis include helping you breathe better (if the excess fluid is causing breathing problems) and finding the cause of the fluid buildup.
After any procedure, you should monitor for signs of an infection or problems healing at the injection site. This may include a fever of 100.4°F or higher, chest pain, or redness and swelling at the site of injection. Inform your care team if you have any of these symptoms.
Some risks associated with a thoracentesis include:
Speak with your doctor about how you can help lower these risks.
Your doctor may analyze the fluid removed from the thoracentesis, looking for several indicators, including:
Other causes of pleural effusion include heart failure, liver disease and malnutrition.
The findings of the pleural fluid analysis can help determine what needs to be done to treat it, if anything.