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Overview

What Is a Pulmonary Embolism?

A pulmonary embolism is a blockage in a blood vessel in the lungs, usually caused by a blood clot that formed in a deep vein of the leg. The clot can break loose, travel through the bloodstream and heart, and lodge in a pulmonary artery. A pulmonary embolism may be manageable when found promptly, but a large or untreated clot can be life-threatening. People of many ages can develop one, especially when certain medical conditions or situations increase the risk of blood clots.

Emergency Warning Signs

Emergency Warning Signs of Pulmonary Embolism

CALL EMERGENCY SERVICES

Get immediate help

Sudden symptoms that could indicate a pulmonary embolism require immediate emergency evaluation. Call your local emergency services rather than driving yourself to the hospital.

  • Sudden shortness of breath can be a warning sign of a blocked blood vessel in the lungs.
  • Sharp or worsening chest pain, especially pain that increases with breathing, needs urgent assessment.
  • Coughing up blood requires immediate medical attention.
  • Fainting or near-fainting may signal that the heart and circulation are under severe strain.
  • A very rapid heartbeat can occur when the body is responding to reduced blood flow.
  • Severe dizziness may be a sign of dangerously low circulation.
  • Blue or gray lips or skin can indicate inadequate oxygen.
  • Sudden collapse is a medical emergency.

Symptoms can begin suddenly or may be less dramatic, but new unexplained breathing difficulty, chest pain or fainting should not be watched at home to see whether it improves. Pulmonary embolism symptoms can worsen quickly, so seek emergency care even if the symptoms seem mild at first.

Symptoms

Symptoms of Pulmonary Embolism

  • Shortness of breath may begin suddenly or worsen with activity.
  • Chest pain may feel sharp and may worsen when taking a deep breath.
  • A rapid or irregular heartbeat may occur.
  • A cough may develop.
  • Coughing up blood (hemoptysis) can occur.
  • Lightheadedness may result from reduced oxygen or circulation.
  • Fainting can occur with a severe blockage.
  • Sweating may accompany breathing or chest symptoms.
  • Anxiety or a sense of impending doom may occur.

Symptoms vary depending on the clot’s size and location and how much it affects blood flow through the lungs. Leg pain, tenderness, swelling, warmth or redness may point to the underlying deep vein thrombosis that caused the embolism. Because these signs overlap with other conditions, urgent medical assessment is important.

Causes

Causes of Pulmonary Embolism

Most pulmonary emboli begin as venous blood clots, usually in a deep vein of the leg or pelvis. The clot can break loose, pass through the right side of the heart and lodge in a pulmonary artery, blocking blood flow through part of the lung.

  • Prolonged immobility, such as extended bed rest or sitting, can slow blood flow and promote clot formation.
  • Recent surgery or hospitalization can raise clot risk because of inflammation and reduced movement.
  • A serious injury can damage blood vessels and activate the body’s clotting response.
  • Pregnancy and the postpartum period naturally increase the tendency for blood to clot.
  • Estrogen-containing medicines, including some contraceptives and hormone treatments, can increase clot risk.
  • Cancer and some cancer treatments can make blood clotting more likely.
  • Inherited clotting disorders can cause an increased tendency to form venous clots.
  • A prior venous thromboembolism increases the chance of another clot.

Most cases are caused by a blood clot, but rare embolisms can result from fat, air or amniotic fluid entering the circulation. These uncommon causes require separate medical evaluation and are not the usual explanation for a lung embolism.

Risk Factors

Risk Factors for Pulmonary Embolism

Risk categoryExamples
Non-modifiable or medical risksOlder age; previous clots; inherited thrombophilia; cancer; pregnancy; and some serious medical conditions.
Potentially modifiable or situational risksSurgery; hospitalization; prolonged travel or sitting; obesity; smoking; estrogen exposure; and limited mobility.

Several risk factors can occur together, increasing the likelihood of a pulmonary embolism blood clot in the lungs. However, some embolisms happen without an obvious trigger. Discuss your personal risk with a clinician before surgery, long travel, pregnancy or starting hormone treatment.

Complications

Complications of Pulmonary Embolism

  • Low blood oxygen can occur when blocked blood flow prevents normal oxygen exchange.
  • Right-sided heart strain or failure may develop as the heart pumps against increased pressure in the lung arteries.
  • Shock can occur when the embolism severely reduces circulation.
  • Cardiac arrest is a possible consequence of a major untreated clot.
  • Recurrent pulmonary embolism can happen if another clot forms and travels to the lungs.
  • Death can result from a large clot, severe heart strain or delayed treatment.

Chronic thromboembolic pulmonary hypertension

A small number of people develop persistent blockage and high pressure in the lung arteries after a pulmonary embolism. This chronic thromboembolic pulmonary hypertension can cause ongoing shortness of breath, reduced exercise tolerance and strain on the heart.

Diagnosis

How Pulmonary Embolism Is Diagnosed

Clinicians review symptoms, vital signs, medical history, risk factors and physical findings before estimating how likely a pulmonary embolism is. They then choose blood tests and imaging based on the person’s clinical situation.

  • A D-dimer blood test can help assess whether a clotting process may be occurring in people with a lower or intermediate likelihood of disease.
  • CT pulmonary angiography uses contrast imaging to look for a clot in the pulmonary arteries.
  • A ventilation-perfusion scan compares airflow and blood flow in the lungs to identify a mismatch suggesting blockage.
  • Leg ultrasound can detect deep vein thrombosis that may have caused the embolism.
  • Electrocardiography records the heart’s electrical activity and may show effects of strain or help identify other causes of symptoms.
  • A chest X-ray helps assess other causes of breathing or chest symptoms, although it usually cannot directly show a pulmonary embolism.
  • Echocardiography can assess heart strain and circulation, especially when the person is seriously ill.

Treatment & Management

Pulmonary Embolism Treatment and Management

Treatment depends on whether the person is stable, the size and location of the clot, the degree of heart strain, bleeding risk and whether a provoking cause is present. Pulmonary embolism treatment may range from anticoagulant medicine and monitoring to urgent procedures that remove or dissolve the clot.

  • Oxygen and supportive care help maintain breathing, blood pressure and circulation when needed.
  • Anticoagulants prevent existing clots from growing and reduce the risk of new clots.
  • Thrombolytic medicines rapidly dissolve clots in selected life-threatening cases when their benefits outweigh bleeding risks.
  • Catheter-based clot removal uses a thin tube to remove or break up a clot in carefully selected patients.
  • Surgical embolectomy removes a clot through surgery when other approaches are unsuitable or ineffective.
  • An inferior vena cava filter may be considered when anticoagulation cannot be used or is not safe.

Anticoagulant follow-up and recurrence prevention

The duration of anticoagulant treatment is individualized according to the cause of the clot, recurrence risk and bleeding risk. Taking medicine exactly as prescribed and following bleeding precautions are important. Clinicians may also address cancer, hormone exposure, immobility or inherited clotting risk to reduce the chance of another embolism.

Prevention

Preventing Pulmonary Embolism

  • Walk and move your legs regularly during prolonged sitting, including on long trips.
  • Follow postoperative instructions about safe movement and activity.
  • Use prescribed compression devices or stockings as directed.
  • Take preventive anticoagulants exactly as prescribed during high-risk periods.
  • Maintain a healthy weight through sustainable eating and activity habits.
  • Avoid smoking, which can add to cardiovascular and clot-related risks.

ASK YOUR CLINICIAN

Use prevention measures safely

Do not start aspirin, anticoagulants or compression garments for prevention without individualized medical advice, particularly after surgery or during pregnancy. The right option depends on your clot risk, bleeding risk and other health conditions.

Outlook and Prognosis

Outlook and Prognosis After Pulmonary Embolism

Many people recover with prompt diagnosis and treatment. However, a large or untreated embolism can rapidly become fatal, and serious medical conditions such as cancer or heart disease can worsen the outlook. Recovery depends on the clot burden, heart strain, treatment speed and overall health.

  • Complete the prescribed anticoagulant treatment unless your clinician changes the plan.
  • Attend reassessment visits so clinicians can monitor recovery and treatment safety.
  • Report unusual bleeding or recurrent breathing symptoms promptly.
  • Gradually resume activity as advised by your healthcare team.
  • Discuss persistent shortness of breath or reduced exercise tolerance with a clinician.

The risk of recurrence varies according to the original cause and ongoing risk factors, so follow-up helps guide prevention. Some people have persistent symptoms or develop chronic thromboembolic pulmonary hypertension, while others return to their usual activity over time. No fixed recovery period or outcome applies to everyone with a lung embolism.

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