A pulmonary embolism (PE) is a blockage within an artery in the lungs. It is a potentially life threatening condition that requires prompt diagnosis and treatment.

Pregnancy causes changes to hormones and blood flow, both of which increase the risk of a PE. Anyone who experiences symptoms of a PE during or shortly after pregnancy should seek immediate medical attention. Without treatment, a PE can be fatal.

In this article, we describe what a PE is and outline the link between PE and pregnancy. We also list the causes and symptoms of a PE and provide information on treating and preventing the condition during and after pregnancy.

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Embolism is the medical term for a blockage in an artery. The majority of these blockages are due to blood clots, most of which originate in the deep veins of the arms, legs, or pelvis. Doctors refer to these clots as deep vein thromboses (DVTs).

A PE occurs when a blood clot or a fragment of a blood clot breaks away and travels to the lung, blocking the pulmonary artery.

Venous thromboembolism (VTE) is a condition that includes both DVT and PE.

Several factors can increase the risk of blood clot formation. They are:

  • slowed blood flow and blood pooling in the deep veins due to immobility or travel
  • damage to the blood vessels resulting from surgery or injury
  • family history of blood clots
  • taking medications that increase the risk of blood clots, such as birth control pills and hormone replacement therapy (HRT)

A person’s risk of a PE increases during pregnancy and in the first 6 weeks following childbirth. This increased risk is due to normal changes in hormone levels and the way in which blood flows through the veins.

Other factors that can contribute to the risk of a PE during and after pregnancy include:

A 2018 review article notes that 3% of maternal deaths worldwide are due to VTE. In the United States alone, VTE accounted for 15% of maternal deaths between the years 2003 and 2011.

The following factors can further increase the risk of a PE during and after pregnancy:

Some of the most common symptoms of PE include:

Anyone who experiences one or more of the above symptoms during or after pregnancy should contact a doctor for a diagnosis and appropriate treatment.

As PE is a serious condition, the diagnostic process will usually take place in a hospital setting.

When diagnosing PE, a doctor will ask about the person’s symptoms, including their onset and severity. They will also take a full medical history.

In some cases, they may order one or more of the following diagnostic tests:

  • Blood tests: A doctor may order any of the following blood tests to help determine whether a clotting disorder is present and, if so, the extent to which it has affected the body:
    • D-dimer: This test checks for the protein D-dimer, which forms when a blood clot dissolves.
    • Brain natriuretic peptide (BNP): Doctors use this test to check for the hormone BNP, with high levels indicating that the heart is not pumping efficiently.
    • Troponin levels: Troponins regulate muscle contraction. Higher blood levels of troponin indicate injury to the heart.
  • Imaging studies: The following imaging tests can help identify blood clots and show issues with blood flow in the lungs:

When using diagnostic imaging to check someone who is pregnant, the doctor will weigh the risks that radiation poses to them and the unborn baby against the risk of missing an important diagnosis. Medical professionals will ensure that any necessary imaging tests use the minimum dose of radiation necessary to make a diagnosis.

A 2017 review describes the challenges of diagnosing a PE in pregnancy. According to the review, people who are pregnant are typically younger and healthier than other people with a PE and may present with different symptoms.

The aim of PE treatment is to stop clots from forming and open up blood flow to the lungs. Several types of medication are available, including:

  • Anticoagulants: These medications help prevent blood clots from forming. A doctor may recommend an anticoagulant called low-molecular-weight heparin (LMWH) for use during pregnancy. Subcutaneous LMWH is the preferred option due to its efficacy and safety profile. Experts recommend against using other categories of anticoagulants, such as vitamin K antagonists, oral direct thrombin inhibitors, or anti-Xa inhibitors, during pregnancy.
  • Thrombolytics: These medications help dissolve existing clots. Although research suggests that there is no link between thrombolytic agents and abnormalities in a developing fetus, the risk of maternal hemorrhage is high. As a result, in people who are pregnant or have recently given birth, doctors will reserve thrombolytic therapy for those with life threatening acute PE.

A person may continue certain anticoagulant treatment for up to 6 weeks or longer following their delivery date. Although certain medications are safe to use when breastfeeding, others may not have enough safety information to confirm this, so a person should check with a doctor.

It is important to be aware that the medications for PE can cause serious bleeding. As such, anyone taking these medications requires frequent monitoring and potential adjustments to their medication dosage.

There are ways to help prevent PE during and after pregnancy. These include:

  • Staying hydrated: Drinking plenty of water will help prevent the blood from thickening and forming clots.
  • Exercising regularly: Unless a doctor has recommended bed rest, a person should try to remain active and exercise regularly. Doing so will help maintain healthy blood flow and prevent the formation of blood clots.
  • Wearing pressure stockings: These stockings promote circulation and help prevent the blood from pooling and clotting in the lower legs.

A person who is pregnant and at increased risk of blood clots should see a doctor for regular health checks. The doctor can determine whether the person would benefit from anticoagulant medications to help prevent blood clots and PE. They can also help manage medications around the time of delivery.

Anyone with symptoms of a PE should seek medical help immediately, especially if they are pregnant. A blockage within a pulmonary artery can increase blood pressure in the vessels of the lung. Without treatment, this can cause heart failure or even death.

After diagnosing PE, a doctor may send a person home with medications to help dissolve an existing clot or prevent a new clot from forming. The doctor will closely monitor medication dosages to keep the blood from getting too thin. Symptoms that suggest that the blood may be too thin include:

  • vomit that is bright red or resembles coffee grounds
  • bloody or tarry stools
  • pain in the abdomen or head
  • changes in vision
  • inability to move the arms and legs
  • confusion

Anyone who experiences any of the above symptoms should contact a doctor immediately.

A pulmonary embolism is a blockage within a pulmonary artery in the lungs. Most PEs result from a blood clot that originated within a deep vein in the arm, leg, or pelvis. Medical experts refer to these clots as deep vein thromboses.

Pregnancy causes changes to hormones and blood flow, both of which increase the risk of developing a PE. Anyone who experiences symptoms of a PE during or shortly after pregnancy should seek medical attention immediately. Without treatment, a PE can cause heart failure and even death.

A person who is taking medications to help prevent or manage PE during pregnancy will require routine monitoring and may require adjustments to their medication dosages. These precautions will help maximize the chance of a safe delivery.