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Pulmonary embolism

Your health expert: Dr Richard Russell, Respiratory Consultant
Content editor review by Rachael Mayfield-Blake, Freelance Health Editor, August 2022
Next review due August 2025

A pulmonary embolism is a blocked blood vessel in your lungs. It’s a serious and potentially life-threatening condition if you don’t get a quick diagnosis and treatment.


An image showing where a pulmonary embolism occurs

Causes of pulmonary embolism

The most common cause of a pulmonary embolism is deep vein thrombosis (DVT). This is a blood clot in your leg or your pelvis. The clot can move (or bits can break off) and travel through your bloodstream until it gets to your lungs, where it gets stuck. This then affects your blood flow and breathing.

Some things can increase your risk of developing a blood clot. These include:

  • being inactive for long periods of time; for example, if you’re recovering after a big operation or are sitting still during a long journey
  • having blood that clots more easily; for instance, if you’re overweight, pregnant or are taking the contraceptive pill
  • having cancer, particularly prostate cancer and breast cancer
  • your blood vessels being damaged from an injury or operation
  • having a genetic disorder that makes it more likely for your blood to clot

For more information about the risks of travel and pulmonary embolism, see our FAQ on flying below.

Symptoms of pulmonary embolism

Symptoms of a pulmonary embolism may include:

  • pain in your chest
  • feeling short of breath
  • coughing up blood
  • feeling faint or fainting

Your symptoms may depend on how big the pulmonary embolism is and where it is. For example, if the clot is small and in a blood vessel at the outer edge of your lungs, you may have mild symptoms. If the blood clot is large and in a central blood vessel, it could cause you to collapse suddenly.

If you have pulmonary embolism symptoms, including difficulty breathing and chest pain, call an ambulance and get medical help as soon as you can. Also get emergency help if you’re pregnant, or have given birth in the last six weeks.

Sometimes the symptoms of a pulmonary embolism can be vague and nagging for several weeks, or they can be sudden and severe. Some people have few, if any, symptoms. Pulmonary embolism symptoms can also be caused by other health conditions, but if you have any of them, see a GP as soon as possible.

Diagnosis of pulmonary embolism

If the GP thinks you have signs of a pulmonary embolism, they’ll probably give you some treatment and arrange for you to go to hospital for assessment as soon as possible. It may well be that you’re in hospital (after an operation, for example) when the symptoms come on.

At hospital, you may have the following tests.

  • A blood test called D-dimer. If the test result is negative, this may help to rule out DVT and a pulmonary embolism.
  • A leg vein ultrasound. This uses sound waves to look at your blood as it flows through the blood vessels in your legs.
  • Computed tomography pulmonary angiogram (CTPA). This is a CT scan where you have dye injected into your bloodstream to see if there’s a blockage in the arteries (blood vessels) to your lungs.
  • Isotope lung scanning (also called ventilation-perfusion or V/Q scanning). You may be offered this test if you have kidney problems or can’t have a CTPA for some other reason. It shows how much blood and air are getting into your lungs.

Your doctor may do other tests such as a chest X-ray, an ECG and blood tests, to confirm whether you have a pulmonary embolism or another condition.

Treatment of pulmonary embolism

If you have a pulmonary embolism, it’s important that it’s treated quickly. This means that you’ll usually begin pulmonary embolism treatment while you’re waiting for tests, or for test results. You may need to be admitted to hospital, if you’re not already in hospital. You may be given oxygen to help you breathe, and fluid through a drip if necessary.

The main pulmonary embolism treatment is a type of medicine called an anticoagulant. You may also need treatment to get rid of the existing clot.

Anticoagulants

Anticoagulants prevent blood clots forming or stop blood clots getting bigger. Which type of anticoagulant your doctor recommends will depend on a number of things. These include how serious your pulmonary embolism is and your general health, as well as local guidelines and availability of treatment.

You have some anticoagulant medicines to treat a pulmonary embolism as an injection, and others you can swallow as tablets. If you have a pulmonary embolism, your doctor will probably recommend you have an anticoagulant called heparin, then start taking anticoagulant tablets.

There are two main types of oral anticoagulant medicines:

  • direct oral anticoagulants (DOACs), such as apixaban, rivaroxaban, dabigatran, and edoxaban
  • warfarin

DOACs may be the first option your doctor recommends. These medicines have the advantage that you don’t need to be monitored as closely as with older anticoagulants like warfarin.

If you’re taking warfarin, you’ll need to have regular blood tests to make sure the medicine is having the correct blood-thinning effect. This is called an international normalised ratio (INR) test. You won’t need to be monitored in this way if you’re taking a DOAC.

After a pulmonary embolism, you’ll need to keep taking anticoagulants for at least three months. Depending on your medical history and why you developed a pulmonary embolism, your doctor may recommend you continue taking anticoagulants for longer. This is to prevent any more blood clots developing.

If you’re taking an anticoagulant, your nurse or doctor should give you an anticoagulant information booklet and an alert card, which you should always carry with you.

Treatments to remove clots

If your doctor thinks you have a life-threatening pulmonary embolism, you may need treatment to remove it. You may be given a type of medicine called a thrombolytic. These help to dissolve the blood clots.

If you’re seriously unwell with life-threatening blood clots or other treatments haven’t worked, your doctor may suggest an operation to remove the blood clot. This is called an embolectomy. There are several different ways in which this can be done. You can have an embolectomy using a catheter. This is when a surgeon puts a thin tube inside your vein and moves it to where the clot is. Your surgeon can then break up the clot via the catheter and remove it. Or you can have open surgery, where your surgeon makes a cut in the blood vessel to take out the clot.

Prevention of pulmonary embolism

Preventing pulmonary embolism in hospital

If you're in hospital for a big operation or because of illness, you may be more likely to develop a deep vein thrombosis or a pulmonary embolism. When you’re in hospital, your nurse or doctor will measure your risk of developing a blood clot, and may ask you to do the following.

  • Drink plenty of fluids. If you can’t drink, you’ll be given fluids through a drip.
  • Get up and start moving about as soon as you can after an operation or illness.
  • Wear compression stockings to help your circulation.
  • Use an intermittent pneumatic compression device. This is an inflatable cuff wrapped around your leg or foot and an electrical pump that inflates it, squeezing your deep veins.
  • Have anticoagulant medicines, such as heparin.

 

Reducing risks of pulmonary embolism when travelling

You can find out about the risks of getting a DVT or pulmonary embolism when travelling from our FAQ on flying below.

There are some simple steps you can take to reduce your chances of getting a blood clot when you’re travelling.

  • Get up and walk around whenever you can.
  • Wear loose-fitting clothing.
  • Do leg exercises in your seat; for example, bend and straighten your knees, feet and toes every half hour.
  • Drink enough water (at least 250ml every 2 hours) so you don’t become dehydrated, and don’t drink a lot of alcohol.

If you’ve had recent surgery, have had a blood clot before or have other health problems that make developing a clot more likely, speak to a GP. They may suggest you wear compression stockings or flight socks while travelling.

If you develop a painful and swollen leg or any breathing problems after a long journey, get medical advice as soon as you can. Be aware that it can take hours, days or even weeks before you notice anything.

Pulmonary embolism and pregnancy

You’re four or five times more likely to develop a blood clot (DVT and pulmonary embolism) if you're pregnant (although it’s rare to get one). You also have a greater chance of having a pulmonary embolism just after you’ve had your baby, especially if you had a caesarean section.

There are some anticoagulants (medicines that prevent your blood clotting) that may harm a developing baby, so you shouldn't take these when you're pregnant. These include warfarin and direct oral anticoagulants. See our treatment section above for descriptions of these medicines. If you’re taking warfarin or other anticoagulant tablets, and think that you might be pregnant, tell your doctor immediately.

If your doctor thinks you're at high risk of getting a blood clot, they may offer you heparin injections while you’re pregnant. Heparin is safe to take when you’re pregnant because it doesn’t pass from you to your baby. You may need to take anticoagulant medicines for at least six weeks after you have your baby.

The chance of developing a pulmonary embolism if you’re a young woman is very small. The chances, if you’re taking the combined hormonal contraception pill, are also very small, but they’re greater than if you’re not taking it.

Your doctor will discuss other things that may increase your chances of getting a pulmonary embolism before prescribing the contraceptive pill. These include your age, whether or not you’re overweight and if you have a family history of blood clots.

See our section: Causes of pulmonary embolism above for more information.

If you travel long distances, and spend more than about four hours sitting down, then you could be more likely to develop deep vein thrombosis (DVT). A DVT could potentially then lead to a pulmonary embolism. The longer the journey, the greater the risk. And the risk is greater if you have other health conditions or risk factors too. See our section: Prevention of pulmonary embolism above for more information.

The main cause of a pulmonary embolism is deep vein thrombosis (DVT): a blood clot in your leg or your pelvis. The clot can move (or bits can break off) and travel through your bloodstream until it gets to your lungs, where it can get stuck and cause a pulmonary embolism.

See our section: Causes of pulmonary embolism above for more information.

You’re at higher risk of developing a blood clot, which may cause a pulmonary embolism, if you’re inactive for long periods of time. For example, if you’re recovering after a big operation or do long-distance travel. If you’re overweight, pregnant or are taking the contraceptive pill, it can also increase your risk. Your genetics can also play a role.

See our section: Causes of pulmonary embolism above for more information.

Symptoms of a pulmonary embolism usually come on suddenly rather than gradually so you’ll often know something is wrong. But less often, the symptoms can be vague and nagging for several weeks. Some people have few, if any, symptoms.

See our section: Symptoms of pulmonary embolism above for more information.

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