What are the different types of pulmonary embolism?

Hearing the words pulmonary embolism (PE) for the first time can feel like someone just dropped a medical horror movie into your life. It sounds intenseand to be fair, it can be. A pulmonary embolism is a blockage in an artery in your lungs, usually caused by a blood clot that has traveled from somewhere else in the body, most often a deep vein in the leg (deep vein thrombosis, or DVT).

But not all pulmonary embolisms are the same. Some are small and caught early. Others are large, dangerous, and immediately life-threatening. Doctors talk about many types of pulmonary embolism depending on how the clot behaves, where it sits, what it’s made of, and how sick it makes you.

Understanding these different types doesn’t mean you have to become a cardiologist overnight. It simply helps you make sense of what your medical team is saying and why they’re choosing certain tests or treatments. Let’s walk through the main categories of pulmonary embolism in plain Englishno white coat required.

Quick refresher: What is a pulmonary embolism?

A pulmonary embolism happens when somethingusually a blood clotblocks one of the arteries that carry blood from your heart to your lungs. That blockage disrupts normal blood flow and reduces the amount of oxygen that can move from your lungs into your bloodstream. In severe cases, a big clot can strain the right side of the heart and cause dangerously low blood pressure or even sudden death.

Most of the time, the clot doesn’t start in the lungs. It forms in a deep vein in the leg or pelvis, then breaks loose, rides the venous “highway” through the heart, and eventually lodges in the pulmonary arteries. That combo of DVT and PE is called venous thromboembolism (VTE).

Now, on to the fun part (okay, “fun” in a nerdy health-education way): how doctors divide pulmonary embolism into different types.

How doctors classify pulmonary embolism

There isn’t just one universal system. In practice, doctors use several overlapping ways to describe pulmonary embolism:

• By how sick or unstable the person is (risk-based types)
• By where the clot is in the lungs (anatomic types)
• By how long it has been there (acute vs. chronic)
• By what the clot is made of (thrombotic vs. nonthrombotic)

These categories help guide treatment decisionssuch as whether someone needs clot-busting medication, a catheter-based procedure, surgery, or just blood thinners and close monitoring.

Types of pulmonary embolism based on risk and severity

This is one of the most important ways doctors talk about PE, because it’s directly tied to how urgent and aggressive treatment needs to be. You’ll often hear about:

High-risk (massive) pulmonary embolism

A high-risk or massive pulmonary embolism is the medical equivalent of a five-alarm fire. In this type, the clot is causing hemodynamic instabilitymeaning the blood pressure is dangerously low, the heart is struggling, or the person is in shock.

Doctors generally call a PE “massive” or high-risk when there is:

• Persistent low blood pressure (systolic blood pressure under about 90 mm Hg)
• A big drop in blood pressure from baseline
• Signs of shock such as confusion, very cool or clammy skin, or poor urine output

This type of pulmonary embolism is a true emergency. Treatment may include clot-busting medications (thrombolytics), catheter-directed therapies, or even surgery in some cases, usually in an intensive care unit. The goal is to restore blood flow and relieve the extreme strain on the heart as quickly as possible.

Intermediate-risk (submassive) pulmonary embolism

Next step down the ladder: intermediate-risk or submassive pulmonary embolism. Here the blood pressure is still within normal limits, but the clot is big enough to put serious pressure on the right side of the heart.

Doctors look for warning signs such as:

• Right ventricular (RV) dysfunction on an echocardiogram or CT scan
• Elevated cardiac biomarkers (like troponin or BNP), which suggest heart strain or injury
• Shortness of breath, chest discomfort, rapid heart rate, or low oxygen levels

Submassive PE is a “gray zone.” Some people do well with blood thinners alone, while others may benefit from more aggressive, but still carefully selected, treatments. That’s why risk scores, lab tests, imaging, and close monitoring are so important for this group.

Low-risk pulmonary embolism

A low-risk pulmonary embolism is still seriousbut compared to massive or submassive PE, it’s the more “stable” cousin. In low-risk PE:

• Blood pressure is normal
• There are no signs of right-heart dysfunction on imaging or blood tests
• Symptoms may be milder, such as pleuritic chest pain (worse with deep breaths), mild shortness of breath, or a small area of lung tissue damage (pulmonary infarction)

Many people with low-risk pulmonary embolism are treated with blood thinners and careful follow-up. In some casesand only in carefully selected patientstreatment can even be managed partly at home after initial evaluation.

Types of pulmonary embolism based on where the clot is

Another way to talk about types of pulmonary embolism is by the anatomic location of the clot in the pulmonary arteries.

Saddle pulmonary embolism

This one has a dramatic name. A saddle pulmonary embolism is a clot that sits right where the main pulmonary artery splits into the right and left brancheslike a saddle over a horse. Because it sits at a major “intersection,” it often represents a large clot burden.

Saddle PEs can be dangerous, but interestingly, not all of them cause shock or low blood pressure. Some people with saddle PE are relatively stable; others are critically ill. Again, the overall risk category (high, intermediate, or low) depends on blood pressure, heart strain, and other clinical featuresnot the name alone.

Lobar, segmental, and subsegmental pulmonary embolism

Doctors may also describe a PE based on the size of the blood vessels involved:

• Lobar PE: The clot blocks one of the major branches supplying a whole lobe of the lung.
• Segmental PE: The clot is in a smaller branch called a segmental artery.
• Subsegmental PE: The clot is in a very small, peripheral branch of the pulmonary artery.

Subsegmental PEs, especially if they are isolated and the patient has no major risk factors or symptoms, spark lots of discussion: should they always be treated with blood thinners, or sometimes just monitored? That decision is very individualized and something physicians weigh carefully.

Acute vs. chronic pulmonary embolism

Not every PE is a sudden, one-time event that disappears and never bothers you again.

Acute pulmonary embolism

When people talk about PE, they usually mean an acute pulmonary embolisma clot that formed recently, often within days or weeks, and is causing sudden or rapidly developing symptoms such as shortness of breath, chest pain, or fainting.

The main treatment is anticoagulation (blood thinners) to keep the clot from growing and to reduce the chance of new clots forming while the body gradually breaks down the existing clot.

Chronic thromboembolic disease and CTEPH

In some people, clot material doesn’t fully dissolve. Instead, it becomes organized and scar-like, sticking to the walls of the pulmonary arteries. When this leads to persistent high pressure in those arteries and strain on the right side of the heart, it’s called chronic thromboembolic pulmonary hypertension (CTEPH).

CTEPH can cause:

• Shortness of breath with activity
• Fatigue
• Leg swelling
• Signs of right-sided heart failure

CTEPH is relatively rare but important to recognize, because some patients can be treated with specialized surgery, balloon procedures in the pulmonary arteries, or targeted medications.

Types of pulmonary embolism based on what causes the blockage

When most people say “pulmonary embolism,” they mean a thrombotic PEa clot made of platelets and fibrin, like other blood clots. But not all blockages are classic blood clots. Some are called nonthrombotic pulmonary emboli, made of other materials.

Classic thrombotic pulmonary embolism

This is by far the most common type. The clot:

• Usually starts in a deep vein of the leg or pelvis (DVT)
• Can happen after surgery, long travel, immobility, injury, pregnancy, cancer, or due to inherited clotting disorders
• Is treated primarily with anticoagulant medications

Nonthrombotic pulmonary embolism

Less common, but medically fascinating (and often serious), are PEs caused by “foreign” material in the bloodstream. These include:

• Fat embolism: Tiny fat droplets, often after long-bone fractures or major orthopedic surgery, can travel to the lungs and cause breathing problems, confusion, and rash as part of fat embolism syndrome.
• Air embolism: Air bubbles accidentally introduced into the venous systemfor example, through certain medical procedures or line mishapscan reach the pulmonary circulation and block blood flow.
• Amniotic fluid embolism: A rare but life-threatening complication of pregnancy and delivery in which amniotic fluid or fetal debris enters the bloodstream and triggers a severe reaction in the lungs and cardiovascular system.
• Tumor embolism: Cells from certain cancers can break off and lodge in pulmonary vessels, obstructing blood flow.
• Septic emboli: Clumps of infected material, such as those from certain heart valve infections, that travel to and block pulmonary arteries.
• Foreign-material emboli: Bits of medical devices, injected substances, or bone cement used in orthopedic procedures that unintentionally travel to the lungs.

These nonthrombotic types are less common than classic blood clots, but they’re a reminder that “pulmonary embolism” is really a broader concept: any obstructing material traveling to the pulmonary arteries.

Why the type of pulmonary embolism matters

You might be thinking, “Okay, but what does all this labeling actually do for me?” Good question. The type of pulmonary embolism helps your healthcare team decide things like:

• How urgently you need treatment
• Whether you need ICU-level care or can stay on a regular hospital floor
• Whether blood thinners alone are enoughor if you might benefit from thrombolysis, catheter-based therapy, or surgery
• How long you may need to stay on anticoagulants (months vs. possibly lifelong)
• Whether you need follow-up testing for conditions like CTEPH

The labels“massive,” “submassive,” “saddle,” “subsegmental,” and so onare really shorthand for a bigger picture: how your heart, lungs, and overall body are handling the clot, and what the safest treatment plan looks like for you.

When to seek emergency care

Regardless of the type, pulmonary embolism is nothing to self-diagnose or watch casually like a TV rerun. Seek immediate emergency care if you notice:

• Sudden or worsening shortness of breath
• Chest pain that gets worse when you breathe in
• Coughing up blood
• Fainting, near-fainting, or confusion
• A very fast heartbeat or a feeling of “impending doom”

These symptoms don’t always mean PE, but they always deserve urgent medical evaluation. If you’ve had a recent surgery, long flight, injury, pregnancy, or known clotting disorder, mention that to the emergency team.

Real-world experiences with different types of pulmonary embolism

Every pulmonary embolism is unique, because every person and every body is unique. But certain patterns show up again and again. The following are fictional, composite stories based on common clinical scenariosmeant to help you picture how different types of PE can feel and how people navigate them.

Emma’s story: Intermediate-risk PE after a long flight

Emma is 32, generally healthy, and just got back from a 14-hour international flight. She brushed off her slightly swollen calf as “weird travel stuff.” Two days later, while walking up the stairs at home, she suddenly felt short of breath and had a sharp pain in her chest when she tried to take a deep breath.

At the emergency department, her oxygen level was a little low, her heart was racing, but her blood pressure was normal. A CT scan showed clots in the segmental arteries of both lungs. Blood tests and an ultrasound of her heart showed that the right side of her heart was under strain. Her doctors labeled it an intermediate-risk (submassive) pulmonary embolism.

Emma spent several days in the hospital on blood thinners with continuous monitoring. The team debated whether to use catheter-based therapy but ultimately decided against it because she stayed stable and her numbers began to improve. Months later, she’s back to hikingbut she’s religious about compression socks on flights and moving around every hour. She also had testing for underlying clotting disorders to understand her future risk.

George’s story: Chronic thromboembolic disease sneaking up

George is 68 and likes to joke that his main hobby is “collecting doctors.” After a PE several years ago, he stayed on blood thinners for a while and then transitioned off under supervision. Over the next couple of years, he noticed that walking from the parking lot to the grocery store left him more winded than before. He blamed age, then weight, then “just being out of shape.”

Eventually, his shortness of breath and leg swelling got bad enough that he brought it upagainto his cardiologist, who ordered additional testing. A specialized scan showed chronic clot material and high pressure in the arteries of his lungs. He was diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH).

This wasn’t great news, but it did open the door to new options: referral to a center that performs surgical or catheter-based procedures to remove chronic clot material, along with medications to help manage the high pressures. George jokes that he still gets winded, but now he knows it’s not just “getting old” and that there’s a plan in place.

Lena’s story: A rare nonthrombotic embolism after childbirth

Lena is 29 and had just given birth to her first baby. Shortly after delivery, she suddenly became very short of breath, her oxygen levels plummeted, and her blood pressure dropped. The room that moments ago was full of happy tears turned into an emergency scene. She was rushed to intensive care.

Her doctors suspected a rare complication: amniotic fluid embolism, where material from the amniotic fluid enters the bloodstream and triggers a severe reaction in the lungs and heart. Technically, this is a type of pulmonary embolismbut not the usual blood clot kind.

With intensive support, Lena’s condition gradually stabilized. Her recovery was longer and more complicated than she’d imagined when she pictured “bringing baby home,” but she got there. She now tells other expecting parents: “Ask what your hospital does to watch for blood clots and rare complications. You don’t need to be scaredbut it’s okay to be informed.”

What these experiences have in common

Emma, George, and Lena faced very different types of pulmonary embolismintermediate-risk, chronic thromboembolic disease, and a rare nonthrombotic embolism. But they share some core themes:

• Symptoms matter. Sudden shortness of breath, chest pain, fainting, or a major change in exercise tolerance shouldn’t be ignored.
• Early evaluation changes outcomes. The sooner doctors identify the type and severity of PE, the more options they have.
• Follow-up is key. Even after an acute PE improves, ongoing care helps catch chronic complications and manage long-term risks.
• Education empowers. Understanding terms like “massive,” “submassive,” “CTEPH,” or “nonthrombotic” can make conversations with your care team less overwhelming.

Real-world experiences also highlight that pulmonary embolism isn’t just a chapter in a textbook. It’s a life event that affects work, family, mental health, travel plans, and confidence in your own body. Asking questions, bringing a support person to appointments, and seeking credible information sources can make the journey less frightening and more manageable.

The bottom line

Pulmonary embolism isn’t a single, one-size-fits-all condition. There are many different types of pulmonary embolismhigh-risk (massive), intermediate-risk (submassive), and low-risk; saddle vs. segmental vs. subsegmental; acute vs. chronic; thrombotic vs. nonthrombotic. Each label tells your healthcare team something about how serious the situation is, what may have caused it, and which treatment strategies might be safest and most effective.

If you or someone you love has been told they have a pulmonary embolism, it’s absolutely okay to ask:

• “What type of PE do I have?”
• “How serious is it?”
• “What treatments are we considering and why?”
• “What should I watch for after I go home?”

This article is for education and general understanding only and cannot replace personalized advice from your medical team. But the more you know about the different types of pulmonary embolism, the better prepared you are to participate in decisions about your careand to spot symptoms early if they ever show up in your life again.