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What Is Thoracentesis?

Thoracentesis (THOR-ah-sen-TE-sis) is a procedure to remove excess fluid in the space between the lungs and the chest wall. This space is called the pleural space.

Normally, the pleural space is filled with a small amount of fluid—about 4 teaspoons full. Some conditions—such as heart failure, lung infections, and tumors—can cause more fluid to build up. When this happens, it's called a pleural effusion (PLUR-al e-FU-shun). A lot of extra fluid can press on the lungs, making it hard to breathe.

Overview

Doctors use thoracentesis to find the cause of a pleural effusion. The procedure also might be done to help you breathe easier.

During the procedure, your doctor inserts a thin needle or plastic tube into the pleural space. He or she draws out excess fluid.

Your doctor may take only the amount of fluid needed to find the cause of the pleural effusion. However, if you have a lot of fluid in your pleural space, he or she may take more. This helps the lungs expand and take in more air, which allows you to breathe easier.

After the fluid is removed from your chest, it's sent for testing. Once the cause of the pleural effusion is known, your doctor will plan treatment. For example, if an infection is causing the excess fluid, your doctor may prescribe antibiotics. If the cause is heart failure, you'll be treated for that condition.

Thoracentesis usually takes 10–15 minutes. It may take longer if you have a lot of fluid in your pleural space. You'll be watched for up to a few hours after the procedure for complications.

Outlook

Thoracentesis usually doesn't cause serious problems, but some risks are involved. Risks include:

Pneumothorax (noo-mo-THOR-aks), or a collapsed lung
Pain, bleeding, bruising, or infection at the spot where the needle or tube was inserted
Liver or spleen injury (very rare)

Sometimes these problems get better on their own. If not, your doctor will likely prescribe treatment.

Who Needs Thoracentesis?

Your doctor may recommend thoracentesis if you have a pleural effusion. A pleural effusion is the buildup of excess fluid in the pleural space (the space between the lungs and chest wall).

Doctors use thoracentesis to find the cause of a pleural effusion. The procedure also might be done to remove excess fluid from the pleural space and help you breathe easier.

The most common cause of a pleural effusion is heart failure. This is a condition in which the heart can't pump enough blood to the body.

Other causes include lung cancer, tumors, pneumonia, tuberculosis, pulmonary embolism (PULL-mun-ary EM-bo-lizm), and other lung infections. Asbestosis (as-bes-TOE-sis), sarcoidosis (sar-koy-DO-sis), and reactions to some drugs also can lead to a pleural effusion.

Diagnosing a Pleural Effusion

Your doctor will diagnose a pleural effusion based on your medical history, a physical exam, and test results.

Medical History

Your doctor will ask about your symptoms, such as trouble breathing, coughing, and hiccups. He or she also may ask whether you've ever:

Had heart disease
Smoked
Traveled to places where you may have been exposed to tuberculosis
Had a job that exposed you to asbestos (a mineral that, in the past, was widely used in many industries)

Physical Exam

Your doctor will listen to your breathing with a stethoscope and tap lightly on your chest. If you have a pleural effusion, your breathing may sound muffled. Your doctor also may hear a dull sound when tapping on your chest.

Diagnostic Tests

You may have one or more of the following tests to diagnose a pleural effusion.

Chest x ray. This test creates a picture of the structures inside your chest, such as your heart and lungs. A chest x ray may show air or fluid in the pleural space. The test also may show the cause of the pleural effusion, such as pneumonia or a lung tumor. To get more detailed pictures, the x ray might be done while you're in various positions.
Ultrasound. This test uses sound waves to create a picture of the structures in your body, such as your lungs. Ultrasound may show the location of fluid in your chest. Sometimes the test is used to find the right place to insert the needle or tube for thoracentesis.
Chest computed tomography (to-MOG-rah-fee) scan, or chest CT scan. This test creates a computer-generated picture of the lungs that can show pockets of fluid. A chest CT scan may show fluid even if a chest x ray doesn't. A CT scan also may show signs of pneumonia or a tumor.

What To Expect Before Thoracentesis

Before thoracentesis, your doctor will talk to you about the procedure and how to prepare for it. Tell your doctor:

Whether you're taking any medicines and which ones you're taking
About any previous bleeding problems you've had
Whether you have allergies to medicines or latex

No special preparations are needed before thoracentesis.

What To Expect During Thoracentesis

Thoracentesis is done at a doctor's office or hospital. The entire procedure (including preparation) usually takes 10–15 minutes, but the needle or tube is in your chest for only a few minutes during that time. If you have a lot of fluid in your pleural space, the procedure may take up to 45 minutes.

You'll sit on the edge of a chair or exam table, lean forward, and rest your arms on a table. You'll be asked to not move, cough, or breathe deeply once the procedure begins.

Your doctor may use ultrasound to find the right place to insert the needle or tube. Ultrasound uses sound waves to create a picture of the structures in your body, such as your lungs.

Your doctor will clean the area on your skin where the needle or tube will be inserted. Then, he or she will inject medicine to numb the area. You may feel some stinging at this time.

Your doctor will insert the needle or tube between your ribs and into the pleural space (the space between the lungs and chest wall). You may feel some discomfort and pressure at this time.

Using the needle or tube, your doctor will draw out the excess fluid around your lungs. You may feel like coughing, and you may feel some chest pain.

Thoracentesis

The image shows a person having thoracentesis. The person sits upright and leans on a table. Excess fluid from the pleural space is drained into a bag.

Once the fluid is removed, your doctor will take out the needle or tube. He or she will place a small bandage on the site where the needle or tube was inserted.

What To Expect After Thoracentesis

After thoracentesis, you may have a chest x ray to check for any lung problems. Your blood pressure and breathing will be checked for up to a few hours after the procedure. This is done to make sure you don't have complications.

Your doctor will let you know when you can return to your normal activities, such as driving, physical activity, and working.

Once at home, call your doctor right away if you have any breathing problems.

What Does Thoracentesis Show?

Your doctor will send the fluid removed during thoracentesis for testing. The fluid will be checked for signs of heart failure, infection, cancer, or other conditions that may cause a pleural effusion (the buildup of fluid between the lungs and chest wall).

Once the cause of the pleural effusion is known, your doctor will talk to you about a treatment plan. For example, if an infection is the cause, you may need antibiotics to fight the infection. If the cause is heart failure, you'll be treated for that condition.

What Are the Risks of Thoracentesis?

The risks of thoracentesis usually are minor. They include:

Pneumothorax. This is a condition in which air collects in the pleural space (the space between the lungs and chest wall). Sometimes air comes in through the needle, or the needle makes a hole in the lung. Usually, a hole will seal itself. If enough air gets into the pleural space, however, the lung can collapse. Your doctor may need to put a tube in your chest to remove the air and let the lung expand again.
Pain, bleeding, bruising, or infection where the needle or tube was inserted. Although rare, bleeding can occur in or around the lungs. Your doctor may need to put a tube in your chest to drain the blood. Sometimes surgery is needed to treat the bleeding.
Liver or spleen injuries. These complications are very rare.

Your doctor may do a chest x ray after the procedure to check for lung problems.

Links to Other Information About Thoracentesis

NHLBI Resources

Pleurisy and Other Pleural Disorders (Health Topics)

Non-NHLBI Resources

Thoracentesis (MedlinePlus)
Pleural Effusion (MedlinePlus)

Clinical Trials

Children and Clinical Studies
Clinical Trials (Health Topics)
NHLBI Clinical Trials
NIH Clinical Research Trials and You (National Institutes of Health)
ResearchMatch (funded by the National Institutes of Health)