Thoracentesis

A thoracentesis is a procedure used to drain fluid from the space between the lungs and the wall of the chest (pleural cavity). It is done by inserting a thin, hollow needle between the ribs, through the chest wall and into the pleural cavity. A thoracentesis may also be called a pleural tap or chest tap.

Normally, there is a small amount of fluid in the space between the lungs and the chest wall. This fluid acts as a lubricant so the lungs move smoothly when you breathe.

Sometimes a medical problem can cause extra fluid to build up in the pleural cavity (called pleural effusion). This can make it hard for your lungs to fully inflate and work properly, which can lead to shortness of breath and may cause discomfort.​

You may need to have a thoracentesis if you have trouble breathing and tests that show a buildup of fluid in the pleural cavity.

Your doctor will do this procedure to:

• remove fluid from the pleural cavity
• collect a sample of fluid to find out what is causing it to build up in the pleural cavity

A thoracentesis is usually done as an outpatient procedure. This means that you won't have to stay in the hospital or clinic overnight.

You will be awake during the procedure. Your doctor will use a local anesthetic to numb your skin so you don't feel pain.

A thoracentesis usually takes about 20 minutes. It may take longer if there is a lot of fluid to remove.

In some cases, the fluid may build up again. If this happens, you may need to go to the hospital for monitoring and more tests. This could take a few days.

Your healthcare team will tell you how to prepare for a thoracentesis. They may send you for an imaging test, such as a chest x-ray or CT scan. These tests will help them determine how much fluid is around your lungs.

Tell your healthcare team about all prescription and non-prescription medicines you are taking. You may need to stop taking certain medicines that increase the risk of bleeding, including blood thinners (anticoagulants).

Sitting on the edge of a bed, you will lean forward to rest your arms on a small table. Being in this position widens the spaces between the ribs to make it easier to do the thoracentesis.

Your doctor may use an ultrasound to find the best place to do the procedure. After cleaning the skin, your doctor will apply a local anesthetic to numb the area. Then they will pass a thin needle between the ribs, through the chest wall and into the pleural cavity. The doctor uses a syringe or tubing connected to a vacuum bottle to pull out the fluid.

You may cough or have some pain in your chest during a thoracentesis. But once your doctor has removed the fluid, your lungs will be able to expand more fully and you will breathe easier.

If there is a lot of fluid or your doctor thinks that it might build up again, you may need to have a chest tube (also called a drainage catheter). Your doctor will place one end of the tube in the pleural cavity. The other end will be attached to a container outside of your body. The chest tube will allow the fluid to continue to drain over a few days. You will stay in the hospital until the fluid fully drains so you may not need to keep going back to the hospital or clinic to see your doctor.

When the extra fluid has been removed, your doctor will take out the needle or tube and put a bandage over the cut. They will send a small amount of fluid to a lab to be tested.

Your doctor will send you for a chest x-ray after a thoracentesis. They will use the x-ray to see if the lungs have fully expanded or if there are any other problems in the pleural cavity.

Your healthcare team will tell you if there is anything you can't do for a while after a thoracentesis. Contact them as soon as possible if you notice any unusual symptoms after you get home, such as coughing up blood.

Side effects can happen with any procedure. The most common side effect from a thoracentesis is discomfort or pain where the needle or tube was inserted into the chest.

Other side effects are rare but may include:

• bruising or bleeding
• infection
• a collapsed lung

• buildup of fluid within the lungs (pulmonary edema)

If you have pleural effusion, the fluid sample collected during the thoracentesis will be tested in a lab. The lab results can help your doctor find out what caused the pleural effusion.

Many types of cancers can cause pleural effusion, including:

• lung cancer
• breast cancer
• non-Hodgkin lymphoma
• Hodgkin lymphoma
• ovarian cancer

Other conditions that can cause pleural effusion include:

• blood clots blocking a blood vessel in the lung (called pulmonary embolism)
• heart failure (a condition in which the heart doesn't pump enough blood to the body)
• kidney failure
• liver failure
• pneumonia

Your healthcare team will decide if you need further tests, procedures, follow-up care or more treatment.

Preparing children for a test or procedure by explaining what will happen during the test, such as what the child will see, feel and hear, can be very helpful. Preparing children before a test or procedure can help lower their anxiety, make them more cooperative and develop their coping skills.

How you prepare your child for a thoracentesis depends on your child's age and experience. Find out more about helping your child cope with tests and treatments.