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Medical provider sitting on a patient table, explaining a thoracentesis procedure to a female patient

What is thoracentesis?

Thoracentesis is a procedure that uses a catheter to drain fluid or air from the space between the outer lining of the lungs and the inner lining of the chest wall, called the pleural space. It is commonly used for pleural effusion, a condition where excess fluid builds up in the pleural space, which can cause breathing difficulties.

Your care team may also test the drained fluid to help diagnose conditions like infections or cancer. This quick, routine procedure is performed while you are awake.

Paracentesis vs. thoracentesis

Both paracentesis and thoracentesis are procedures to remove extra fluid from the body. They can relieve symptoms and diagnose the cause of the excess fluid accumulation. Paracentesis drains fluid from the abdomen to treat ascites, a condition where fluid accumulates in the peritoneal cavity (the space containing organs like the intestines, stomach and liver). It relieves symptoms such as bloating and abdominal pain. Thoracentesis removes excess fluid or air in the pleural cavity to treat pleural effusion.

Thoracentesis vs. chest tube

Thoracentesis and a chest tube use different methods to drain fluid or air from around the lungs. Thoracentesis is a procedure that temporarily places a catheter into the pleural space. It takes about 15-30 minutes, and the catheter is removed at the end of the procedure. A chest tube uses a flexible plastic or rubber tube placed in the pleural space to drain fluid or air over several days. You may have a chest tube placed by a pulmonologist, a surgeon or a radiologist.

Why is a thoracentesis procedure performed?

Excess fluid around your lungs can cause discomfort and trouble breathing. One of the main reasons your doctor may perform a thoracentesis procedure is to reduce these symptoms. If the exact cause of the fluid buildup isn’t known, thoracentesis is also performed to take fluid samples for lab testing to look for the underlying cause.

Many different conditions lead to excess fluid around the lungs, but some common causes are congestive heart failure and infections like pneumonia or cancer. Some types of cancer are more likely to lead to this buildup. For instance, about 40% of people with lung cancer will develop pleural effusion.

The types of cancer most likely to cause pleural effusion include:

 

Other conditions that cause fluid buildup and might need thoracentesis include:

Male patient sitting in a doctor's office as a medical provider explains how to prepare for a thoracentesis

Preparing for a thoracentesis

Your doctor will give you specific details on how to prepare for your thoracentesis. You may need to stop taking certain medications, like blood thinners, and you’ll want to plan for a support person to come to the procedure with you and drive home.

Make sure to let your doctor know about all health conditions and medications, including blood thinning medications, herbs and supplements, allergies, pregnancy, bleeding disorders or lung conditions.

What to expect during the thoracentesis procedure

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Thoracentesis is a quick, minimally invasive procedure that takes 15-30 minutes. You’ll usually be awake during thoracentesis and may have this procedure in a doctor’s office, at an outpatient center or the hospital.

At your care center, you’ll change into a gown, have monitors placed to track your vitals and sign consent forms. To plan your procedure and determine where fluid needs to be removed, your care team will use imaging tests, like X-rays, CT or ultrasound, before starting your thoracentesis procedure.

Position of thoracentesis

Most of the time, thoracentesis is performed while sitting on a chair or in a bed with your arms on a table in front of you. This position gives your doctor access to your side and back, and slightly spreads out the space between your ribs, which helps placement of the thoracentesis catheter. If you can’t sit for the procedure, it can also be performed with you reclining halfway or lying on your side.

Draining fluid from lungs

Your provider will usually first perform an ultrasound of your chest to find and mark the fluid collection, inject a local anesthetic to numb the area, and then insert the thoracentesis catheter mounted on a needle into the pleural cavity. Once the fluid collection is reached, the needle is removed, and the catheter is used to drain the fluid from the space around your lungs. You might feel some discomfort in your chest, shoulder or both. This is usually resolved over the next couple of hours with over-the-counter pain medications.

Your doctor will also give you instructions on when to stay still, hold your breath or breathe out. When enough of the fluid is drained, the catheter is removed, and you’ll have a bandage placed on the area.

After thoracentesis

After your thoracentesis procedure, you may have an imaging test to take another look at your chest and lungs. You will stay at the center, and your care team will monitor you for a short time before you go home. You should be able to eat normally after a thoracentesis and resume your daily activities, but you may take it easy for a couple of days—avoiding strenuous activities or lifting.

Often, your doctor will send the fluid removed during a thoracentesis to the lab for testing. Getting the results after your thoracentesis procedure may take a few days. 

Risks and complications of thoracentesis

Thoracentesis is a safe, minimally invasive procedure, and complications aren’t common. However, there are a few potential risks of a thoracentesis procedure. Your doctor will answer any questions you have about the risks and benefits. Your care team will also give you information about the signs to watch for after your thoracentesis so that you can get timely follow-up care for any complications or side effects.

  • Pain during placement: While you’ll have a local anesthetic to help minimize pain, it’s common to have some mild discomfort when the doctor places the needle for thoracentesis.
  • Bleeding: Bleeding sometimes happens if the needle hits a blood vessel. Typically, this is minor, and it gets better on its own. In rare cases, you may need another procedure to resolve bleeding caused by a thoracentesis.
  • Infection: There is a very small chance of infection around the area where the needle is inserted or a lung infection like pneumonia.
  • Collapsed lung: Rarely, the needle used in thoracentesis can puncture a lung, causing a pneumothorax—or collapsed lung. If this happens, your doctor might need to place a chest tube to remove the buildup of air leaking from the lung.
  • Pulmonary edema: When the fluid around the lungs is removed too fast during thoracentesis, it could lead to fluid buildup inside the lungs, called pulmonary edema.

Frequently asked questions

  • Can fluid come back after thoracentesis?

    Yes, the fluid may come back after a thoracentesis. This depends on what is causing the fluid to build up. If you’re living with a chronic condition like congestive heart failure or cancer, pleural effusion may come back, and you may need additional thoracentesis or other procedures.

  • Do you need to be NPO for thoracentesis (nothing by mouth)?

    Not usually. Unlike surgery, most people aren’t required to stop eating or drinking before a thoracentesis. Only make changes to your diet if your doctor gives you specific instructions before your procedure.

  • How often can a thoracentesis be done?

    Thoracentesis can be performed multiple times when fluid continues to return, as often as every few days. However, multiple procedures may lead to scar tissue or pockets of fluid, making it harder to repeat in the future. It’s important only to have thoracentesis when necessary.

  • How long does a thoracentesis take?

    A thoracentesis procedure usually takes 15-30 minutes to perform. You’ll need to get to your procedure about 30 minutes early to check in and prepare, and you should expect to stay at the center for a short time afterward. In all, reserve one to two hours for the entire process.

  • Is thoracentesis painful?

    Not usually. People often feel mild chest or shoulder discomfort during thoracentesis, but it should not be painful. Your care team will inject a local anesthetic at the procedure site, which can cause a few seconds of stinging or burning but greatly reduces the procedure-related pain in the area.