Thoracentesis: what to Expect

Just as bakers use teaspoons to measure cinnamon and sugar, doctors use them to measure the fluid between your lungs and chest wall.

There are normally 4 teaspoons of fluid in this area, known as the “pleural space.” A variety of things can cause that amount to go up.

When this happens, it’s called pleural effusion. It puts extra pressure on your lungs, making it hard to breathe. To remove the excess fluid and find out what's causing it, doctors use a procedure called thoracentesis.

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When doing a thoracentesis, a doctor uses imaging guidance to put a needle through your chest wall and into the pleural space. Depending on the severity of your condition, it can be a short, outpatient procedure.

Why Do I Need a Thoracentesis?

During the thoracentesis, your doctor removes fluid from the pleural space. This eases your shortness of breath, chest pain, and pressure on your lungs.

That fluid is then tested to figure out the reason behind the build-up. The most common cause is congestive heart failure, which is when your heart doesn’t properly pump out blood to your body.

Some of the other conditions that might cause fluid build-up include:

  • An area of pus in the pleural space (called an “empyema”)
  • Blood clot in the lung
  • Cancer
  • High blood pressure in the lung blood vessels (“pulmonary hypertension”)
  • Liver failure
  • Pneumonia
  • Reactions to medicine
  • Tuberculosis
  • Viral, fungal, or bacterial infections

How Should I Prepare?

In addition to your doctor's directions, keep the following in mind:

  • You may have a blood test before the procedure. This can show how your kidneys are doing and let your doctor know whether your blood clots normally.
  • Make a list of all medications and supplements you’re taking and allergies you have, including those to anesthesia (a type of medical treatment that stops you from feeling pain during surgery).
  • Let your doctor know if you think you may be pregnant.
  • Schedule someone to drive you home because you’ll likely be groggy from medicine you’ll be given to numb pain during the procedure.

What Happens During a Thoracentesis?

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The thoracentesis may start or end with a chest X-ray to check your lungs. From there, most cases happen this way:

  • You'll sit up on a bed or chair, with your arms resting on a table. This position spreads out the space between the ribs.
  • The area where the needle will be inserted is cleaned and numbed. Sometimes, younger children will be given medicine that causes them to be sleepy.
  • The doctor will insert the needle between the ribs in your back and fluid will be withdrawn.
  • The doctor may ask you to be still, exhale, or hold your breath at different times.
  • Once enough fluid has been drained, the needle will be removed and the area will be bandaged. The spot where the needle went in will close without any stitches.

This normally is a 15-minute procedure. If there is a lot of fluid to remove, it may take longer.

What Happens Afterwards?

While fluid samples are sent off for examination, a nurse will closely watch your blood pressure, pulse, and breathing. Your bandage may also be checked before you're released.

Follow all diet and physical activity directions and call your doctor if you have any of these symptoms:

  • Fever of 100.4 F or higher
  • Redness, swelling, blood or other fluid leaking from needle site
  • Breathing issues or chest pain

What Can Go Wrong?

Every surgical procedure has some potential problems. Though thoracentesis is generally considered safe, these complications can happen:

  • Pulmonary edema, or fluid in the lungs
  • Pneumothorax, or collapsed lung
  • Infection at the site where the needle pierced your skin
  • Liver or spleen injury (rare)

What Do the Results Mean?

After evaluating the lab work from your fluid, your doctor will let you know the results and come up with a treatment plan.

For example, an infection caused by bacteria may be treated with antibiotics.

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