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What Is a Thoracentesis Procedure?

What You Need to Know About Thoracentesis

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Dayton Respiratory Center

Jan 06 2023

6 mins read

Our lungs are responsible for vital functions — like oxygenating our blood.

But the organs are delicate. Some medical conditions cause fluid to accumulate around the lungs, hindering normal breathing. Eliminating this fluid is necessary for survival.

Doctors can remove excess fluid through thoracentesis.

Let's dive deeper into thoracentesis. We'll discuss the benefits, risks and how to prepare for the procedure.

What Is Thoracentesis?

Thoracentesis is a medical procedure to remove excess fluid from the pleural space.

The pleura is a thin layer of tissue that lines your lungs and walls of your inner chest. A small amount of fluid between these two layers (pleural space) helps them move smoothly past each other as your lungs expand and contract during breathing.

However, conditions like pneumonia, cancer, heart failure, and pulmonary embolism can cause pleural effusion (i.e., excess fluid accumulation). This makes breathing difficult.

Why Do We Need to Perform Thoracentesis?

Pleural effusion is usually detected using imaging tests — such as X-rays or CT scans. To officially diagnose the condition, a doctor may need to remove a fluid sample for laboratory testing by performing a thoracentesis (i.e., a pleural puncture).

What Are the Benefits of Thoracentesis?

Thoracentesis can benefit the patient in the following ways:

  • Symptom relief — Thoracentesis relieves shortness of breath and chest pain caused by pleural effusion
  • Improved lung function — Removing excess fluid from the pleural space can help improve lung function and increase oxygen levels in the blood
  • Diagnosis — A sample of the fluid removed during thoracentesis can be sent for laboratory testing to help diagnose the cause of the pleural effusion and guide treatment
  • Treatment — Thoracentesis can help treat the underlying condition causing the pleural effusion. For example, if the pleural effusion is caused by an infection, removing the fluid can help improve the patient's condition and reduce the risk of further complications
  • Non-invasive — Thoracentesis is a relatively non-invasive procedure that can be performed in a hospital or clinic setting. It's generally safe and has a low risk of complications

What Are the Common Complications Of Thoracentesis?

Thoracentesis is a relatively safe and commonly performed medical procedure. But, like any procedure, it carries some risks and potential complications, such as:

  • Bleeding — If the needle hits a blood vessel, bleeding may occur. This bleeding is usually minor and stops on its own, but in rare cases, surgery may be needed to address the bleeding
  • Infection — There's a risk of infection at the insertion site. However, proper sterilization techniques minimize the risk
  • Pneumothorax — Sometimes, while draining the pleural space, atmospheric air accidentally enters the pleural space, causing a pneumothorax (i.e., a collapsed lung)
  • Pulmonary edema — If thoracentesis removes too much fluid from around the lungs too quickly, it may cause fluid to build up inside the lungs
  • Pain — Some patients experience discomfort or pain during or after the procedure

Overall, the risks and complications of thoracentesis are generally low, but it is important to discuss any concerns with a healthcare provider before the procedure.

How Do I Prepare for Thoracentesis?

If you are scheduled to undergo a thoracentesis, follow these steps to prepare for the procedure:

  1. Make sure you understand the purpose of the procedure and know what to expect. Ask your healthcare provider any questions you may have
  2. Inform your healthcare provider about any allergies, sensitivities, and medications you're currently taking
  3. Follow your healthcare provider's instructions — such as fasting before the procedure or stopping certain medications
  4. Inform your doctor if you're pregnant or are unsure about it
  5. Wear comfortable, loose-fitting clothes. You may be asked to change into a hospital gown
  6. Remove any jewelry, glasses, dentures, or other metal objects
  7. Plan for someone to drive you home after the procedure — you might not be able to drive yourself

By following these steps, you can help ensure that your thoracentesis goes smoothly and that you are prepared for the procedure.

Where Do I Go for a Thoracentesis Procedure?

Thoracentesis is typically performed in a hospital or clinical setting by a healthcare provider with specialized training — such as a radiologist or a pulmonologist.

What Happens During a Thoracentesis Procedure?

Before the procedure, you’ll need to remove any metal objects — such as eyeglasses and jewelry — and change into a hospital gown.

Your healthcare provider might ask you to sit with your arms on the table or lie on your side. This position allows them to access the pleural fluid easily.

Your physician will disinfect the insertion site with an antiseptic solution and administer local anesthesia.

The physician will insert a needle through the insertion site that reaches the pleural space and drain any excess fluid into a bag.

During this part of the procedure, you’ll need to stay still and exhale deeply or hold your breath when instructed by your physician.

Once the procedure is complete, your physician will remove the needle, bandage the insertion site, and send the fluid to a lab for testing.

How Long Does Thoracentesis Procedure Take?

Thoracentesis is a short procedure that typically takes 10 to 15 minutes. Sometimes, a follow-up chest X-ray may be taken to ensure no complications.


What Happens After a Thoracentesis Procedure?

After the thoracentesis procedure, your doctor will closely monitor your vital signs, including your blood pressure, pulse, and breathing. They'll also check the insertion site to ensure no bleeding or fluid discharge.

Thoracentesis is generally an outpatient procedure, so you can go home if everything goes well. You can resume your regular diet and activities, but you may be advised to avoid strenuous exercise.

Watch for any symptoms after the procedure — such as a high fever (above 100.4°F), pain, swelling or redness at the insertion site, shortness of breath, and bleeding or fluid discharge at the insertion site.

Inform your healthcare provider immediately if you experience any of these symptoms.

When Can I Expect the Results of Thoracentesis?

The results of a thoracentesis procedure depend on the type of laboratory tests performed on the fluid collected during the procedure. Some tests, such as cell count or chemical analysis, provide results within a few hours. Others, such as bacterial cultures, may take several days.

Your healthcare provider will discuss the timing of the test results with you and explain when you can expect to receive them. Make sure you follow up with your healthcare provider to discuss the results and any recommended treatment plan.


Thoracentesis is a minimally invasive procedure that helps relieve the pressure on your lungs due to excess fluid in the pleural space. The process is relatively quick and has a low risk of complications when performed by a trained healthcare provider. Talk to your doctor if you have any concerns regarding the procedure.

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