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Test Overview

Pericardiocentesis is done to find the cause of fluid buildup around the heart and to relieve pressure on the heart. The tissue sac that surrounds the heart is called the pericardium. It protects the heart and parts of the major blood vessels connected to the heart. Normally, there is a small amount of fluid between this sac and the heart. This fluid surrounds and helps cushion the heart. It helps reduce friction between the heart and other structures in the chest when the heart beats.

Some diseases cause fluid to collect within the pericardium. This fluid collection is called pericardial effusion.

The test may be done to find the cause of a pericardial effusion. During this test, a needle is inserted into the chest and into the pericardium to remove a sample of the fluid. The fluid is sent to a lab where it is measured and checked for blood, microorganisms (such as bacteria, fungi, or viruses), white blood cells, sugar (glucose), cancer cells, and other substances.

Pericardiocentesis may also be done to treat pericardial effusion by removing the blood or excess pericardial fluid surrounding the heart. This helps relieve pressure on the heart. The pressure from excess fluid can prevent normal filling of the heart, which can reduce the heart's ability to pump blood (cardiac tamponade).

Why It Is Done

Pericardiocentesis is done to:

  • Relieve pressure on the heart.
  • Find the cause of pericardial effusion.

How To Prepare

You may not be able to eat or drink for several hours before the test.

Because this is a test involving your heart, you may have to stay overnight in the hospital to be monitored closely. If a drain is inserted during the test, you may have to stay for several days.

Unless the procedure is being done in an emergency, you will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.

How It Is Done

You may get a mild sedative to help you relax. You will get a shot of anesthetic to numb your skin and deeper tissues. Then a long, thin needle will be carefully inserted just below your breastbone. (In some cases, the needle is inserted between your ribs on the left side, over your heart.)

The needle is then slowly pushed through the pericardial sac into the space between the sac and your heart. This is where the extra fluid is.

Your doctor may use an echocardiogram to help guide the needle. Or an X-ray camera may be used to guide it.

The doctor may guide a thin plastic tube along the needle into the space between the sac and your heart. The fluid drains out through the tube. Some fluid may be saved and sent to a lab for tests. At different times during the procedure, you may be asked to hold your breath. You must remain very still throughout the procedure.

After some or all of the fluid is drained, the tube may be removed right away. Or the tube may be left in for up to a few days. Pressure is applied to the injection site for several minutes to stop any bleeding.

After the procedure, you will have a chest X-ray to check for possible puncture and collapse of your left lung. You will be closely watched for several hours.

How long the test takes

This procedure takes 10 to 20 minutes. In some cases, the doctor will let the fluid drain through the tube for a few hours.

How It Feels

You will feel a brief stinging pain when the local anesthetic is injected. When the needle is inserted into the pericardial sac, you may feel pressure. You might feel pain in another location, such as your shoulder. You may also have some irregular or "skipped" heartbeats during the test.

Tell your doctor right away if you have severe chest pain or feel short of breath during or after the procedure.


During pericardiocentesis, it is possible for the needle to puncture your heart or one of your blood vessels. The needle may also puncture your lung, your liver, or your stomach. These complications are not common. If problems happen during the procedure, doctors can likely fix them right away. You may need surgery to fix a problem.

If the needle touches your heart, you may have an irregular heartbeat (arrhythmia). But the irregularity usually stops when the needle is removed. In rare cases, this type of arrhythmia can cause death. There is also a chance of spreading infection from the skin to the pericardial space when the needle is inserted.


Some results will be available within hours, while others may take days or weeks.



No bacteria or cancer cells are present in the pericardial fluid.

Few or no white blood cells (WBCs) or red blood cells are in pericardial fluid.

The pericardial fluid is clear or pale yellow.


The pericardial fluid contains bacteria or cancer cells.

A lot of white blood cells or red blood cells are in the pericardial fluid.

The pericardial fluid looks cloudy.

Abnormal values

A buildup of pericardial fluid may be caused by:

  • Inflammation of the sac that surrounds the heart (pericarditis).
  • Infection from a virus, bacteria (such as Mycobacterium tuberculosis, the bacterium that causes tuberculosis), or fungi. Viruses are a common cause of pericarditis.
  • Other diseases, such as cancer or lupus.
  • Blood, which may be present after a heart attack with possible rupture of the heart muscle, a dissecting aortic aneurysm, recent surgery, injury, or cancer.


Current as of: February 26, 2023

Author: Healthwise Staff
Clinical Review Board
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