Thoracentesis: Preparation, Procedure & Risks


What Is a Thoracentesis?

Between the lungs and the chest wall there’s a small space called the pleural space. This space typically contains approximately 4 teaspoons of fluid. Some conditions can cause more fluid to enter this space. These conditions include:

  • tumors
  • pneumonia
  • congestive heart failure
  • chronic lung diseases

This is called pleural effusion. If there’s excess fluid, it can compress the lungs and cause difficulty breathing.

Fluid in the Chest (Pleural Effusion)

Thoracentesis is a procedure done when there’s too much fluid in the pleural space. The goal is to drain the fluid and make it easier for you to breathe again. In some cases, the procedure will also help your doctor discover the cause of the pleural effusion.

The amount of fluid drained varies depending on the reasons for performing the procedure. It typically takes 10 to 15 minutes, but it can take longer if there’s a lot of fluid in the pleural space.

Your doctor may also perform a pleural biopsy at the same time to get a piece of tissue from the lining of your inner chest wall. Abnormal results on a pleural biopsy can indicate certain causes for the effusion, including:

  • the presence of lung cancer
  • mesothelioma, which is an asbestos-related cancer of the tissues that cover the lungs
  • tumors
  • collagen vascular disease
  • viral or fungal diseases
  • parasitic disease

Preparing for a Thoracentesis


There’s no special preparation for a thoracentesis. Tell your doctor about any supplements or medications you’re taking or if you have any bleeding problems.

What Is the Procedure for a Thoracentesis?


Thoracentesis can be done in a doctor’s office or in a hospital. It’s typically done while a patient is awake, but you may be sedated. You’ll need someone else to drive you home after the procedure if you’re sedated.

After sitting in a chair or lying on a table, you’ll be positioned in a way that allows the doctor to access the pleural space. An ultrasound may be done to ascertain the correct area where the needle will go. The selected area will be cleaned and injected with a numbing agent.

Your doctor will insert the needle or tube below your ribs into the pleural space. You might feel an uncomfortable pressure during this process, but you should keep very still. The excess fluid will then be drained out.

Once all the fluid is drained, a bandage will be put on the insertion site. To ensure there are no complications, you’ll be asked to stay in the office for several hours to be monitored. A follow-up X-ray is typically ordered two to four weeks after thoracentesis.

What Are the Risks of the Procedure?

Risk Factors

Every invasive procedure has risks, but side effects are uncommon with thoracentesis. Possible risks include:

  • pain
  • bleeding
  • a collapsed lung
  • infection

Your doctor will go over the risks before the procedure.

Thoracentesis is not a safe or appropriate procedure for everyone. Your doctor will determine if you’re a good candidate for thoracentesis. People who’ve had recent lung surgery may have scarring, which can make the procedure difficult.

Patients who should not undergo thoracentesis include:

  • patients with a bleeding disorder
  • patients with heart failure or enlargement of the right side of the heart
  • patients on blood thinners

Following Up After the Procedure


After the procedure is over your vitals will be monitored, and you may have an X-ray of your lungs taken. Your doctor will allow you to go home if your breathing rate, blood pressure, and pulse are good. Most people who have a thoracentesis can go home the same day.

You’ll be able to return to most of your normal activities after the procedure. However, your doctor may recommend that you avoid physical activity for several days after the procedure.

Your doctor will explain how to take care of the puncture site. Make sure to call your doctor if you begin to:

  • have trouble breathing
  • cough up blood
  • have a fever or chills
  • feel pain when you take deep breaths
  • have any new bleeding from the needle site

These could be signs of an infection.

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