What Is Pericardiocentesis?

Your heart sits inside a thin, double-layered sac called the pericardium. Normally there's just a small amount of fluid between those layers, enough to let the heart move smoothly as it beats. Trouble starts when fluid builds up in that space faster than it can clear. The sac doesn't stretch much, so the extra fluid begins to squeeze the heart from the outside — and a heart that can't fill properly can't pump properly either.

Pericardiocentesis is the procedure that relieves that pressure. Using a needle, and then usually a thin tube, a doctor drains the excess fluid or blood out of the pericardial sac so the heart has room to work again. This page walks you through what to expect if you — or someone close to you — is told this procedure is needed.

The clip at the top of this page, "Pericardiocentesis", is very brief — just eight seconds — but it states the essentials plainly. Its own description calls it "the technique of insertion of a tube into the pericardial sac to remove fluid or blood, improving cardiac function". Treat it as a snapshot of the idea; the longer teaching video linked further down shows the emergency context in much more detail.

When fluid around the heart becomes an emergency

A slow build-up of fluid — a pericardial effusion — sometimes causes few symptoms at first, and small effusions found on a scan may simply be watched. Causes vary: inflammation of the sac (pericarditis), infection, kidney or thyroid problems, cancer, or fluid collecting after heart surgery or a heart attack. The picture changes when fluid accumulates quickly or in large amounts. The pressure inside the sac then rises until it restricts the heart's filling — a state called cardiac tamponade. Breathlessness, chest discomfort, a racing pulse, light-headedness and falling blood pressure can follow, and tamponade is treated as an emergency because the circulation can deteriorate fast.

That's the setting in which pericardiocentesis is most often done urgently: not as a routine test, but as the fastest way to take pressure off the heart. A longer video on this site, "Emergency Pericardiocentesis", walks through exactly that scenario — it describes the procedure as the aspiration of fluid from the space around the heart and explains why it can be life-saving when tamponade develops. In less urgent cases, the same drainage may be planned to identify why fluid has collected, by sending a sample for laboratory testing.

Getting ready: scans, monitors and positioning

Expect imaging to come first. An ultrasound scan of the heart — an echocardiogram — shows where the fluid is, how much there is, and which route in is safest; our guide to what an echocardiogram shows explains how that scan works. You'll be connected to heart and blood-pressure monitors, a small cannula will usually go into a vein, and the skin over the chest or upper abdomen is cleaned and covered with sterile drapes. Most patients are positioned half-sitting, propped up at an angle, because that lets fluid pool where it's easiest to reach. Local anaesthetic numbs the skin, and sedation may be offered if the situation allows — in a true emergency, the team may need to move too quickly for more than the essentials.

The drainage itself, step by step in plain terms

Working under ultrasound guidance — often with an ECG tracing watched at the same time — the doctor advances a fine needle through the numbed area towards the pericardial sac. The entry point varies with where the fluid sits; a common route is just below the breastbone, angled up towards the heart, though an approach through the chest wall is also used. Once the needle tip is confirmed to be in the right space, fluid is drawn off into a syringe. That first syringe of fluid often brings prompt relief when tamponade is present, because even a modest amount removed lowers the pressure in the sac considerably.

In most cases a thin, flexible tube — a small drain — is then passed over a guide wire and left in place, secured to the skin and attached to a closed drainage system. That lets fluid continue to drain over the following hours rather than relying on a single aspiration. Samples of the fluid are usually sent to the laboratory, where testing can point towards the cause — infection, inflammation, bleeding or another process — and guide what treatment comes next.

Afterwards: what recovery usually looks like

You'll be monitored closely after the procedure, typically with repeat checks of blood pressure and heart tracing, and a repeat echocardiogram and chest X-ray are commonly done within the first day to confirm the fluid hasn't reaccumulated and the heart is filling normally. If a drain was left in, the team checks it periodically and drains further fluid as needed; drains of this kind are often removed after a day or two once drainage slows and scans stay reassuring. How you feel depends heavily on why the fluid collected in the first place — people treated for tamponade often feel noticeably easier in their breathing quite quickly, while the underlying cause may still need its own treatment, from medicines for inflammation to further procedures. Our overview of heart failure covers one of the longer-term conditions the team may also be assessing in parallel. New or worsening breathlessness, chest pain or faintness after any heart procedure should always be reported straight away rather than waited out.

References & further reading

MedlinePlus — Pericardiocentesis (Medical Encyclopedia): https://medlineplus.gov/ency/article/003872.htm

MedlinePlus — Pericarditis (Medical Encyclopedia): https://medlineplus.gov/ency/article/000182.htm

NHS — Pericarditis: https://www.nhs.uk/conditions/pericarditis/

Johns Hopkins Medicine — Pericarditis: https://www.hopkinsmedicine.org/health/conditions-and-diseases/pericarditis

Frequently Asked Questions

Is pericardiocentesis the same as open heart surgery?

No. Pericardiocentesis is a needle procedure done through the skin, usually at the bedside or in a procedure room, with local anaesthetic. It doesn't involve opening the chest. Surgery — such as creating a pericardial window — is a separate option the team may consider if fluid keeps coming back or can't be reached safely with a needle.

Will the fluid come back afterwards?

It can, which is why a drain is often left in for a day or two and follow-up scans are arranged. Whether fluid returns depends mainly on its cause; treating that cause — for example, calming inflammation — is what lowers the chance of it building up again.

Does pericardiocentesis hurt?

The skin is numbed with local anaesthetic first, so what most people report is pressure and pushing rather than sharp pain. If you're anxious or uncomfortable, tell the team — in non-emergency settings, sedation can usually be adjusted.

Why is the drained fluid sent for testing?

Because the fluid itself is evidence. Laboratory tests on it can show signs of infection, inflammation, bleeding or cancer cells, and those results often decide what treatment follows the drainage. The procedure can therefore be both a treatment and a diagnostic step in one.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Educational only — this article is general information about pericardiocentesis, not medical advice and not a diagnosis. Whether this procedure, or any treatment, is right for you is a matter for your own care team, who know your results and your history.