Embolism

An embolism is a blockage in a blood vessel that can happen anywhere in your body, most commonly in the lungs. This serious condition requires immediate medical attention, as it stops blood flow and prevents oxygen from reaching vital organs and tissues.

Table of contents

• What is an embolism?
• Types of embolism
• How common is this condition?
• What causes an embolism?
• Risk factors
• Warning signs and symptoms
• How is an embolism diagnosed?
• Treatment options
• Preventing embolisms

What is an embolism?

An embolism is a blockage in your blood vessel that stops blood from flowing properly. This blockage is usually caused by a blood clot that started somewhere else in your body and then traveled through your bloodstream. When this blood clot or another substance becomes an obstacle in a blood vessel, it’s called an embolism^[1].

The blockage prevents blood from moving through the blood vessel and reaching tissues or organs. Because blood carries oxygen that all your cells need to survive, this lack of blood flow can cause serious damage. Some blood vessels may be more likely to have a blockage simply because their size and shape make it easier for things to get stuck. A blockage is more likely to happen when blood vessels become smaller, like where one artery branches off another one, or where plaque buildup (a condition called atherosclerosis) makes an artery narrow^[1].

An embolism is different from a blood clot that forms and stays in one place. When a blood clot forms in a blood vessel, it’s called a thrombus. But when part of that clot breaks off and travels through your bloodstream to block a vessel somewhere else, it becomes an embolism^[2].

Types of embolism

Embolisms differ based on what substance creates the blockage. The most common types include^[1][2]:

• Blood clot (thromboembolism): This is the most common type, where a blood clot travels through your bloodstream and gets stuck in a blood vessel.
• Fat embolism: Fat particles, typically from bone, enter the bloodstream and create blockages. This can happen after bone fractures or certain medical procedures like liposuction.
• Air embolism: Tiny pockets of air or nitrogen enter the bloodstream and form bubbles that block blood flow. This is more common in underwater divers.
• Septic embolism: An infected blood clot travels through the bloodstream.
• Tumor embolism: Pieces of tumor break off and travel through blood vessels.
• Amniotic fluid embolism: This rare type only occurs in pregnant women when amniotic fluid escapes into the bloodstream, typically into the lungs.

Embolisms are also classified by where they occur in the body. Arterial embolisms affect arteries and can cause tissue death from blocked blood supply. An embolus lodging in the brain can cause a stroke. Venous embolisms affect veins. A pulmonary embolism is when a blood clot travels to the lungs and is the most common location for an embolism^[1][2].

How common is this condition?

Embolisms are common. About 900,000 people a year receive a venous thromboembolism diagnosis in the United States^[1].

Pulmonary embolisms are the world’s third leading cause of cardiovascular (heart and blood vessel) death, after strokes and heart attacks^[1]. Venous thromboembolism is more common than arterial thromboembolism.

What causes an embolism?

Most embolisms are pulmonary embolisms that start as blood clots in the leg veins, a condition called deep vein thrombosis (DVT). Sometimes, deep vein thrombosis in the arm veins can also lead to pulmonary embolism^[1][4].

Other causes of embolism include^[1]:

• Infective endocarditis: An infection of the heart valves
• Atrial fibrillation: An irregular heartbeat that can allow blood clots to form in the heart
• Blood clots in the left ventricle of the heart
• Bone fractures from traumatic injury
• Cancer
• Infections
• Pancreatitis
• Liposuction
• Bone marrow transplant
• Gestational diabetes
• Placenta accreta (a pregnancy complication)

Risk factors

Several factors can increase your risk of developing an embolism. The risk factors for the most common type of embolism (from a blood clot) include^[1][9]:

• Physical inactivity or lack of movement
• Surgery and some medical procedures
• Heart failure
• Stroke
• Cancer and cancer treatment
• Trauma or injury
• High blood pressure (hypertension)
• Tobacco product use
• Birth control pill use or hormone replacement therapy
• Conditions that make blood clot too easily (such as inherited clotting disorders)
• Pregnancy and childbirth
• Age (people older than 60 are at greatest risk)
• Obesity
• Recent heart attack
• Certain medical conditions such as diabetes and autoimmune conditions

Blood clots can form when there is damage to the lining of blood vessels, when blood flow is sluggish or slow (such as during long periods of sitting), or when blood is thicker or more likely to clot than normal^[7].

Warning signs and symptoms

When you have an embolism in an artery, it blocks blood that’s trying to get through. Blood carries oxygen that all your cells need. If blood can’t get through, oxygen can’t either. This lack of oxygen causes an “infarct” and damages the organ that needs oxygen. In some cases, this lack of oxygen can be fatal^[1].

Small blood clots may break off from a thrombus in a vein and travel back to the right side of your heart, which pumps blood into your lungs. These clots get stuck in the small pulmonary vessels of your lungs and cause a lung infarct. In rare cases, large pulmonary emboli can even block the normal flow of blood from the right heart into your lungs^[1].

Embolism symptoms vary by the type and location of the blockage. Some people don’t have symptoms at all. Common symptoms may include^[1][3]:

• Sudden shortness of breath, which usually appears suddenly and gets worse with physical activity
• Chest pain that may feel like a heart attack, often sharp and felt when breathing in deeply
• Fast breathing (tachypnea)
• Fast heart rate (tachycardia)
• Low oxygen levels (hypoxemia)
• Coughing, possibly with blood
• Weakness
• Headache
• Petechiae (rash-like spots on your upper body)
• Fever
• Swelling in your limb
• Seizures
• Vertigo (dizziness)
• Nausea and vomiting
• Low blood pressure (hypotension)
• Fainting or feeling lightheaded
• Excessive sweating

If you experience sudden shortness of breath, chest pain, difficulty breathing, or coughing up blood, seek emergency medical attention immediately. These symptoms require urgent care^[3][5].

How is an embolism diagnosed?

A pulmonary embolism can be difficult to diagnose, especially if you have underlying heart or lung disease. Your healthcare provider will likely discuss your medical history, perform a physical exam, and order tests^[8].

Doctors use clinical probability scoring systems like the Wells criteria and Geneva score to assess the likelihood of a pulmonary embolism^[4].

Common diagnostic tests include^[8]:

• Blood tests: Your healthcare provider may order a blood test for D-dimer, a substance produced when blood clots dissolve. High levels may suggest an increased likelihood of blood clots, although many other factors can cause high D-dimer levels. Blood tests can also measure oxygen and carbon dioxide levels in your blood.
• Chest X-ray: This shows images of your heart and lungs. Although X-rays can’t diagnose a pulmonary embolism and may even appear normal when one exists, they can rule out other conditions with similar symptoms.
• Ultrasound: A duplex ultrasonography uses sound waves to scan veins to check for deep vein blood clots. This test can look at veins in the thigh, knee, calf, and sometimes the arms.
• CT pulmonary angiography: This CT scan generates X-rays to produce cross-sectional images of your body and is the standard test for diagnosing pulmonary embolism.

Other tests may include ventilation-perfusion scans, pulmonary angiography for the lungs, or additional imaging studies depending on the suspected location of the embolism^[6].

Treatment options

A pulmonary embolism is a medical emergency that requires prompt treatment to remove the clots and restore normal blood flow. The goal of treatment is to dissolve the blood clot, prevent new clots from forming, and minimize damage to tissues^[12].

Treatment varies depending on how many clots there are, the severity and location of the clot, and your overall health, especially if you have preexisting heart or lung conditions^[12].

Medications

Blood thinners (anticoagulants) are the most common treatment for pulmonary embolisms. These medications prevent new clots from forming and help shrink existing clots. Common blood thinners include heparin and warfarin. Your doctor will determine the best medicine for you and will require routine blood tests to monitor how fast your blood is clotting. You can expect to take blood thinners for at least 3 months and possibly much longer. Some people need to take them for life^[12][16].

Clot busters (thrombolytic or fibrinolytic therapy) are more powerful medications that dissolve clots. They are typically given intravenously for significant or life-threatening pulmonary embolisms^[12].

Catheter-based procedures

Some patients may need minimally invasive procedures to treat their pulmonary embolism. These include^[12]:

• Catheter-directed thrombolysis: Delivers clot-busting medication directly to the clot
• Mechanical thrombectomy: Uses a catheter to remove the clot

Advanced catheter-based procedures can safely and effectively remove large clots from the pulmonary arteries. As minimally invasive procedures, recovery time is shorter, and a return to normal activities is possible once your doctor approves^[12].

Supportive care and recovery

Most people can walk and do light housework right away after a pulmonary embolism, but you may get tired easily or feel short of breath. Your doctor probably will give you specific exercises to do for several weeks or months to help boost your strength and breathing^[16].

Recovery can take upwards of several months, and you’ll need to make sure you follow your doctor’s medication and treatment schedule. Long-term anticoagulation is essential to prevent recurrence, with duration tailored to individual risk factors^[4][16].

Preventing embolisms

Because having one embolism increases your risk of having another, it’s important to take steps to prevent future blood clots^[1][18].

To help prevent blood clots in your legs and reduce your risk of embolism^[18][15]:

• Stay active: Try to walk several times a day. Walking helps keep blood moving in your legs.
• Exercise your lower leg muscles if you sit for long periods: Pump your feet up and down by pulling your toes up toward your knees then pointing them down.
• Take breaks during travel: On long car trips, stop and walk around every hour or so. On buses, planes, or trains, get out of your seat and walk up and down the aisle every hour if you can.
• After an illness or surgery, try to get up and out of bed often: If you can’t get out of bed, flex your feet every hour to keep blood moving through your legs.
• Wear compression stockings if your doctor recommends them.
• Maintain a healthy lifestyle: This includes being active, staying at a healthy weight, and not smoking.
• Check with your doctor about whether you should use hormonal forms of birth control or hormone therapy, as these may increase your risk of blood clots.
• Get vaccinated against COVID-19, influenza (flu), and pneumonia.

Follow your doctor’s instructions carefully, take your medicines exactly as prescribed, and attend all follow-up appointments. If you’re taking a blood thinner, be sure you get instructions about how to take your medicine safely, as blood thinners can cause serious bleeding problems^[18].