What Is a Pulmonary Embolism? Causes, Symptoms & Treatment

💡 Quick Summary: At a Glance

What it is: A blood clot — often formed in the leg veins — travels through the bloodstream and blocks an artery in the lungs, a medical emergency that can be life-threatening if untreated.
Warning signs: Sudden shortness of breath, chest pain, fainting, or cyanosis require an immediate ER visit, regardless of your risk factors.
Diagnosis & treatment: Diagnosis relies mainly on CT pulmonary angiography and V/Q scans; treatment centers on anticoagulants, with thrombolytics, IVC filters, or surgery reserved for select severe cases.

🎯 Who This Guide Is For: Anyone experiencing sudden breathing or chest symptoms, and anyone with risk factors such as recent surgery, pregnancy, or upcoming long-distance travel who wants to understand their risk.

A pulmonary embolism occurs when a blood clot (a clump of coagulated blood) that has formed in a vein somewhere in the body — often in the legs — travels through the bloodstream and blocks an artery in the lungs. It is classified as a medical emergency that can be life-threatening if left untreated. If sudden shortness of breath, chest pain, fainting, or cyanosis occurs, you should go to the emergency room immediately, whether or not you have any risk factors.

🚨 Emergency Warning Signs

If any of the following symptoms appear suddenly, do not wait for a scheduled appointment — go to the emergency room immediately.

Sudden shortness of breath or difficulty breathing

Sudden chest pain (including pain that worsens with breathing)

Fainting or a decline in consciousness

Cyanosis — bluish discoloration of the lips or fingertips

Unexplained cough, especially if accompanied by coughing up blood

If left untreated, the mortality rate is reported to be over 30%. With prompt diagnosis and proper anticoagulation therapy, that rate drops to roughly 2%–8%, according to medical information from Myeongji St. Mary's Hospital and European Society of Cardiology guidelines. Rather than trying to judge for yourself whether you have risk factors, it is safer to get tested directly at the emergency room.

A clot that travels to the lungs can block a pulmonary artery, triggering a medical emergency.

🚨 What Is a Pulmonary Embolism? A Medical Emergency Where a Clot Blocks a Pulmonary Artery

A pulmonary embolism develops when a blood clot — often formed in the veins of the legs — travels through the bloodstream and blocks a pulmonary artery. When the blood becomes excessively prone to clotting — a state known as hypercoagulability — clots fail to dissolve naturally and end up blocking a blood vessel; when such a clot blocks a pulmonary artery, blood flow to the lungs decreases and the strain on the right side of the heart increases sharply, which can lead to symptoms such as low blood pressure, shortness of breath, chest tightness, fainting, cyanosis, chest pain, and coughing. For this reason, pulmonary embolism is also commonly known as "economy class syndrome," because situations like long flights or long drives — where the legs stay immobile for extended periods — allow blood to pool in the veins and make clots more likely to form; regardless of seat class, the same risk can occur in any situation involving prolonged immobility, such as bed rest after surgery. Therefore, symptoms that appear suddenly — such as shortness of breath, chest pain, fainting, or cyanosis — require an immediate visit to the emergency room regardless of whether risk factors are present. If you have risk factors but no specific symptoms, checking your risk level through a scheduled appointment may be sufficient. However, if one leg suddenly becomes swollen, painful, and warm, it is safer to have a medical professional evaluate it rather than judging the situation yourself.

Definition and Mechanism of Pulmonary Embolism

In the body, blood clots continually form and then naturally dissolve in an ongoing cycle. Problems arise when the blood becomes excessively prone to clotting (hypercoagulability), causing clots to fail to dissolve and instead block a blood vessel. The name of the resulting condition depends on where the clot lodges: a clot blocking a blood vessel in the brain causes a stroke, one blocking a vessel supplying the heart causes a heart attack (myocardial infarction), and one blocking a pulmonary artery causes a pulmonary embolism. Because the lungs are the organ where blood that has circulated through the body exchanges oxygen and carbon dioxide, a blocked pulmonary artery reduces blood flow to the lungs and sharply increases the strain on the right side of the heart (the chamber that pumps blood to the lungs). As this strain worsens, blood pressure drops and symptoms such as shortness of breath, chest tightness, fainting, cyanosis, chest pain, and coughing can follow — and in the worst cases, it can lead to cardiac arrest.

Who Is at Risk: "Economy Class Syndrome"

Pulmonary embolism is also commonly referred to as "economy class syndrome." This is because sitting for long periods in a cramped seat, such as during a long flight, without moving the legs allows blood to pool in the leg veins, making clots more likely to form. Despite the name, however, the risk has nothing to do with airline seat class — the same risk can arise in any situation involving prolonged immobility, such as long drives or bed rest after surgery.

Symptoms That Require the ER vs. Situations Where a Scheduled Visit Is Enough

Symptoms that appear suddenly — such as shortness of breath, chest pain, fainting, or cyanosis — call for a trip to the emergency room. On the other hand, if you have no specific symptoms but do have risk factors (such as recent surgery, an upcoming long flight, or a family history), checking your risk level in advance through a scheduled appointment may be sufficient. If one leg suddenly becomes swollen, painful, and warm (a finding suggestive of deep vein thrombosis), this may require urgent evaluation depending on how it progresses, so it is safer to have a medical professional check it rather than judging it yourself.

Certain inherited traits and everyday situations can raise your risk of a blood clot forming.

Why Does Pulmonary Embolism Occur? Inherited and Acquired Risk Factors

Pulmonary embolism risk often increases when inherited and acquired factors overlap. Some people are born with a genetic abnormality in their blood-clotting system that makes them prone to forming clots easily, and if a family member has experienced unexplained blood clots at a young age, you may also be in a higher-risk group. Acquired risk factors that increase the likelihood include the recovery period after trauma or major surgery, prolonged immobility, pregnancy and the period around childbirth, long flights or drives, obesity, smoking, high blood pressure, a history of heart disease or stroke, and chemotherapy or hormone therapy — and the more of these factors that overlap, the greater the cumulative risk. The process by which these risk factors lead to actual symptoms generally follows a set sequence: a clot first forms, often in the legs; the clot then breaks loose and travels through the bloodstream to the pulmonary artery, where it blocks the vessel; this reduces blood flow to the lungs and lowers blood pressure throughout the body, producing symptoms such as shortness of breath, chest tightness, fainting, cyanosis, chest pain, and coughing. Depending on the size and extent of the blocked vessel, the intensity of symptoms can range widely, from mild breathlessness to fainting.

Inherited Risk Factors: Genetic Blood-Clotting Disorders

Some people are born with a genetic abnormality in their blood-clotting system that makes them prone to forming clots easily. If a family member has experienced unexplained blood clots at a young age, you may also be in a higher-risk group.

Acquired Risk Factors: Surgery, Pregnancy, Prolonged Immobility, Obesity, Smoking

Acquired risk factors include the following:

Recovery period after trauma or major surgery
Prolonged immobility (e.g., extended hospital stays, wearing a cast)
Pregnancy and the period around childbirth
Long flights or long drives
Obesity, smoking, high blood pressure
A history of heart disease or stroke
Chemotherapy or hormone therapy (including birth control pills)

The more of these factors that overlap, the greater the cumulative risk. For example, someone who smokes, has recently had surgery, and is about to take a long flight faces a combined increase in risk from all three factors acting together.

How Symptoms Develop: Clot → Reduced Blood Flow → Drop in Blood Pressure

Symptoms often progress in a set order. First, a clot forms, often in the legs. This clot then breaks loose, travels through the bloodstream to the pulmonary artery, and blocks the vessel. This reduces blood flow to the lungs, and as blood pressure throughout the body subsequently drops, symptoms such as shortness of breath, chest tightness, fainting, cyanosis, chest pain, and coughing appear. Depending on the size and extent of the blocked vessel, the intensity of symptoms can range widely, from mild breathlessness to fainting.

Doctors typically combine several imaging tests to confirm a pulmonary embolism diagnosis.

Diagnostic Options for Pulmonary Embolism: What Tests to Expect

If a pulmonary embolism is suspected, diagnosis is not made with a single test alone — a combination of tests is used, depending on the severity of symptoms and the resources available at the hospital. A ventilation-perfusion (V/Q) scan uses a radioactive tracer to separately image the air entering the lungs (ventilation) and the blood flow through them (perfusion) for comparison; if air enters normally but blood flow is interrupted in a specific area, this suggests a clot may be present there, making it one of the key tests for diagnosing pulmonary embolism. CT pulmonary angiography is the first-line standard test due to its rapid speed and high accuracy, while a V/Q scan serves as the first-line alternative when CT pulmonary angiography is contraindicated — for example, in cases of severe iodine contrast allergy, severe renal impairment, or pregnancy. CT pulmonary angiography involves injecting contrast dye into an arm vein and then imaging the pulmonary arteries with CT to identify the location of a clot; because results can be obtained relatively quickly, it is the most widely used first-line test in clinical practice, with a reported diagnostic accuracy of 50–100% depending on testing conditions. Pulmonary angiography, which involves inserting a catheter directly into a blood vessel and injecting contrast dye, is known to be the most accurate test, but because it is invasive and involves a heavier contrast dye load, it is performed only when a definitive diagnosis cannot be reached with non-invasive tests alone. In addition, leg ultrasound is used to identify where a clot originated, and echocardiography (heart ultrasound) is used to assess the strain on the right side of the heart and to evaluate prognosis.

Test	Characteristics	When It Is Performed
Ventilation-Perfusion (V/Q) Scan	One of the key tests for diagnosing pulmonary embolism	Suspected when ventilation is normal but a perfusion defect is present
CT Pulmonary Angiography	Diagnostic accuracy of 50–100%; the clot location is visible on imaging	The most widely used first-line test in clinical practice
Pulmonary Angiography	Most accurate, but invasive with a heavier contrast dye load	Only when non-invasive tests cannot confirm the diagnosis
Echocardiography	Assesses right heart function; helps predict prognosis	Used for severe cases
Leg Vein Ultrasound (for clots)	Checks for the presence of a clot in the legs	Used to trace the origin of the clot

Ventilation-Perfusion (V/Q) Scan

This test uses a radioactive tracer to separately image airflow and blood flow in the lungs, then compares the two images. If air enters normally but blood flow is interrupted in a specific area, this suggests a clot may be present there.

CT Pulmonary Angiography

Contrast dye is injected into an arm vein, and CT imaging of the pulmonary arteries is used to identify clot locations, which appear as dark areas on the scan. Because results can be obtained relatively quickly, it is prioritized in emergency situations.

Pulmonary Angiography, Leg Ultrasound, and Echocardiography

Pulmonary angiography is an invasive test in which a catheter is inserted directly into a blood vessel to inject contrast dye; it is performed only in select cases where a definitive diagnosis is needed. Leg ultrasound is used to locate where a clot originated, while echocardiography is used to assess how much strain the right side of the heart is under.

Considerations: Limitations of Testing and Risks/Exclusions by Treatment

Invasiveness and Limitations of Each Test

Every test has its own limitations. A V/Q scan can be difficult to interpret if underlying lung disease is present, and CT pulmonary angiography can pose a risk for patients with contrast dye allergies or reduced kidney function. Pulmonary angiography is known to be the most accurate test, but because it is invasive and requires a larger volume of contrast dye, its use is limited to cases where non-invasive tests cannot confirm a diagnosis. Before undergoing testing, you must inform your medical team in advance about pregnancy status, any history of contrast dye allergy, and kidney function.

💡 Testing During Pregnancy or While Breastfeeding

For pregnant patients in an emergency, CT scans are performed with abdominal lead shielding, keeping fetal radiation exposure well below the 50 mGy safety threshold. For nursing mothers, less than 0.01% of the contrast dye is absorbed by the infant, so breastfeeding can resume immediately after the scan.

Risks by Treatment: Bleeding Risk With Thrombolytics, Indications for Filters and Surgery

When deciding on a treatment approach, the risks must be weighed just as carefully as the benefits. Anticoagulants, which are started as heparin injections and later switched to oral medication, are the most widely used treatment, but because they carry a bleeding risk, the dosage must be adjusted based on regular blood tests. Thrombolytics can rapidly dissolve clots in severe cases, but because they carry a greater bleeding risk than anticoagulants, they are not used in every patient, and patients at high risk of bleeding are excluded from this treatment. An inferior vena cava (IVC) filter is considered only for patients who cannot use anticoagulants or for whom anticoagulants are ineffective, and clot-removal surgery is considered only for severe cases that do not respond to standard treatment. In other words, having dangerous symptoms does not automatically mean that a more aggressive treatment is the safer choice — each treatment option is appropriate only for a specific group of patients.

🚨 Exclusions and Contraindications

Thrombolytics are not used in patients at high risk of bleeding, and are strictly restricted to high-risk (hemodynamically unstable) patients; they are contraindicated in patients with a high bleeding risk, such as recent stroke or recent surgery. An IVC filter is unnecessary for mild cases that respond well to anticoagulants, and is reserved strictly for patients with absolute contraindications to anticoagulants or recurrent embolism despite therapy. Absolute contraindications for thrombolytic therapy include active major bleeding (intracranial or gastrointestinal), recent brain or eye surgery, severe uncontrolled high blood pressure (≥180/110 mmHg), severe thrombocytopenia, or pregnancy — Warfarin in particular is strictly contraindicated during pregnancy due to fetal toxicity risk.

Knowing the typical cost and timeline can help you know what to expect during care in Korea.

Getting Diagnosed and Treated in Korea: Cost, Duration, and Follow-Up

Cost and Duration of Diagnostic Tests

Diagnostic tests for pulmonary embolism generally range from about $20 to $330 USD (30,000–450,000 KRW), spanning a basic D-dimer blood test up to a specialized V/Q scan. Treatments and procedures range more widely, from about $45 to over $8,800 USD (60,000–12,000,000+ KRW), covering everything from monthly oral medications to emergency catheter-based or surgical clot removal (excluding ICU or hospitalization fees).

Diagnostic Test	Time & Visits	Cost (Non-Insured / International)	Key Role
CT Pulmonary Angiography (CTPA)	10–20 min (1 visit)	$135–$220 USD (180,000–300,000 KRW)	1st-line standard (rapid results)
V/Q Scan	30–60 min (1–2 visits)	$185–$330 USD (250,000–450,000 KRW)	1st-line alternative (contrast/renal risk)
Leg Venous Ultrasound	20–40 min (1–2 visits)	$90–$185 USD (120,000–250,000 KRW)	Evaluates deep vein thrombosis (DVT)
Echocardiogram (TTE)	20–30 min (1–2 visits)	$110–$220 USD (150,000–300,000 KRW)	Checks right ventricular strain
Pulmonary Angiography	~60 min (1 admission)	$740–$1,850+ USD (1,000,000–2,500,000+ KRW)	Invasive catheter procedure (inconclusive cases)
D-Dimer Test	10–15 min (1 visit)	$20–$35 USD (30,000–50,000 KRW)	Initial blood screening

In emergency settings (KTAS Level 1–2), diagnosis and treatment are typically completed in a single visit within 1–2 hours.

Duration of Anticoagulant Treatment: At Least 3 Months, Up to 1 Year

Anticoagulant treatment starts with injectable medications such as heparin, then switches to oral medications like warfarin or dabigatran, continuing for at least 3 months. Depending on the risk of recurrence or underlying conditions, treatment may be extended from 6 months up to a maximum of 1 year, during which regular blood tests are used to monitor both medication effectiveness and bleeding risk. Follow-up frequency varies by medication: warfarin typically requires monitoring every 1–3 months, while DOACs (direct oral anticoagulants) are usually checked every 3–6 months. At a non-insured or international-patient rate, each follow-up visit — including consultation and blood tests — costs roughly $35 to $110 USD, plus about $45 to $90 USD per month for DOAC medication. Costs and scheduling can vary depending on the hospital and individual condition.

If You Have Risk Factors: Check Early With Regular Health Screenings

With pulmonary embolism, it is often difficult to notice your own risk factors before symptoms appear. If you have risk factors such as recent surgery, an upcoming long trip, or a family history, one option is to check your cardiovascular risk in advance by reviewing which health screening items are worth checking at your age.

👉 Wondering which health checkups matter most for your age group? See the full screening checklist by age

If you decide to get a regular checkup, preparing in advance is also important for the accuracy of your test results. Checking what to look for when choosing a health screening center and what to follow before testing can help you avoid mistakes on the day of your screening.

👉 Not sure how to choose the right screening center or prepare beforehand? Get tips on choosing a center and pre-test preparation

Next Steps: What to Do Now

Self-Check Your Risk Factors

Check whether any of the following apply to you.

I have a family history of an inherited blood-clotting disorder
I have recently had major surgery or trauma
I have an upcoming long flight or long drive
I am pregnant or in the period around childbirth
I am obese or currently smoke
I have high blood pressure or a history of heart disease or stroke
I am undergoing chemotherapy or hormone therapy

If several of these apply to you, it may help to move your legs and ankles every hour before a long trip, wear compression stockings, and — if walking isn't possible — keep your legs elevated above the level of your heart.

What to Do If Symptoms Occur

If sudden shortness of breath, chest pain, fainting, or cyanosis occurs, go to the emergency room immediately, regardless of your results on the checklist above. Even without symptoms, if several risk factors overlap, discussing your risk level in advance through a scheduled appointment is a safe next step.

❓ Frequently Asked Questions (FAQ)

Q1: If pulmonary embolism symptoms appear, should I go straight to the emergency room?

If shortness of breath, chest pain, fainting, or cyanosis appear suddenly, you should go to the emergency room immediately. This is because it is a medical emergency with a high risk of death if left untreated. If left untreated, the mortality rate is known to be over 30%. In the emergency room, tests such as CT scans allow for relatively rapid diagnosis. Pulmonary embolism symptoms are classified as high-priority emergencies (KTAS Level 1–2), ensuring immediate evaluation with essentially no wait time — diagnosis via CT pulmonary angiography and initial stabilization typically take about 1 to 2 hours.

Q2: Does a long flight really increase the risk of pulmonary embolism? (Economy class syndrome)

Situations involving limited movement, such as long flights or long drives, can create conditions that make clots more likely to form, increasing the risk of pulmonary embolism. This applies to people about to travel long distances, or those who already have other risk factors (such as obesity, smoking, or high blood pressure). When the legs remain immobile for a long time, blood pools in the veins, making clots more likely to form. It helps to move your legs and ankles every hour, wear compression stockings, and consult a doctor about your risk level in advance if needed.

Q3: How long does anticoagulant treatment last?

Treatment starts with injectable medications such as heparin, then switches to oral medication, continuing for at least 3 months; depending on progress, it may last from 6 months up to 1 year. Regular follow-up monitoring is needed during treatment: warfarin is typically checked every 1–3 months and DOACs every 3–6 months, with each visit costing roughly $35 to $110 USD plus about $45 to $90 USD per month for DOAC medication at non-insured/international rates.

Q4: Can anyone receive thrombolytics or an IVC filter?

No. Thrombolytics are not used in every patient because of the associated bleeding risk, and IVC filters are used only in limited cases — for patients who cannot use anticoagulants or for whom they are ineffective. Patients at high risk of bleeding are excluded from thrombolytic treatment, which is strictly restricted to high-risk, hemodynamically unstable patients. Filters are unnecessary for mild cases that respond well to anticoagulants and are reserved for patients with absolute contraindications to anticoagulants or recurrence despite therapy.

Q5: What is the most accurate test for diagnosing pulmonary embolism?

Pulmonary angiography is the most accurate test, but because it is invasive, it is performed only when other non-invasive tests cannot confirm a diagnosis; in practice, CT pulmonary angiography and V/Q scans are used first. CT diagnostic accuracy ranges from 50–100% depending on testing conditions, and a V/Q scan is one of the key tests. Pulmonary angiography is reserved for cases where a diagnosis cannot otherwise be confirmed and involves a heavier contrast dye load.

What Is a Pulmonary Embolism? Causes, Symptoms & Treatment in Korea (2026)