What is a thoracentesis?

Thoracentesis, also known as a pleural tap, is a procedure done when there’s too much fluid in the pleural space. This allows a pleural fluid analysis to be performed in the lab to figure out the cause of fluid accumulation around one or both of the lungs. The pleural space is the small space between the lungs and the chest wall. This space typically contains approximately 4 teaspoons of fluid. Some conditions can cause more fluid to enter this space. These conditions include:

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

The goal of a thoracentesis 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 cancer cells, such as lung cancer
  • mesothelioma, which is an asbestos-related cancer of the tissues that cover the lungs
  • collagen vascular disease
  • viral or fungal diseases
  • parasitic disease

Pleural Fluid Culture »

There’s no special preparation for a thoracentesis. However, you should talk to your doctor if you have any questions or concerns about the procedure. You should also tell your doctor if you:

  • are currently taking medications, including blood thinners like aspirin, clopidogrel (Plavix), or warfarin (Coumadin)
  • are allergic to any medications
  • have any bleeding problems
  • may be pregnant
  • have lung scarring from previous procedures
  • currently have any lung diseases like lung cancer or emphysema

Thoracentesis can be done in a doctor’s office or in a hospital. It’s typically done while you’re 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 may be asked to stay overnight in the hospital to be monitored. A follow-up X-ray may be performed right after the thoracentesis.

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

  • pain
  • bleeding
  • air accumulation (pneumothorax) pushing on the lung causing a collapsed lung
  • infection

Your doctor will go over the risks before the procedure.

Thoracentesis is not an 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.

People who should not undergo thoracentesis include people:

  • with a bleeding disorder
  • taking blood thinners
  • with heart failure or enlargement of the heart with trapped lung

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, oxygen saturation, blood pressure, and pulse are all 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 soon 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 any signs of infection. Symptoms of infection include:

  • trouble breathing
  • coughing up blood
  • fever or chills
  • pain when you take deep breaths
  • redness, pain, or bleeding around the needle site