Venous Thromboembolism (Embolism Venous)

Venous thromboembolism is a serious condition where blood clots form in the veins and can block blood flow, potentially traveling to the lungs and becoming life-threatening. Understanding the warning signs and risk factors can help you seek timely medical care and prevent serious complications.

Table of contents

• What Is Venous Thromboembolism?
• Types of Venous Thromboembolism
• How Common Is This Condition?
• Signs and Symptoms
• Who Is at Risk?
• How Is It Diagnosed?
• Treatment Options
• Preventing Blood Clots
• Possible Complications
• Living After a Blood Clot

What Is Venous Thromboembolism?

Venous thromboembolism (VTE) is a condition that occurs when a blood clot forms in a vein^[1]. The term “thrombo” means blood clot, “embolism” means a circulating particle that causes an obstruction, and “venous” means in the veins^[2].

Blood clotting is normally a healthy response to a cut or wound. Your blood partially solidifies to keep it from leaking too fast. On the outside of your body, this produces a scab. On the inside of your body, it produces a clot. Blood clotting can also be triggered by an infection, which irritates the lining of the blood vessel. When the wound or infection begins to heal, the clot is supposed to dissolve. But sometimes it doesn’t, and sometimes blood clots form when there was no wound at all^[2].

Veins carry blood from the outer parts of your body back to your heart. When a vein is blocked by a clot, blood pools behind the blockage, causing inflammation. Cells ahead of the blockage can’t get the oxygen and nutrients they need. This can do serious damage to the veins, tissues and organs that they feed^[2].

A venous thromboembolism is not the type of blood clot that typically causes a heart attack or stroke. Those are usually caused by blood clots in your arteries, not in your veins. However, a VTE can be just as dangerous^[2].

Types of Venous Thromboembolism

VTE includes two main conditions: deep vein thrombosis and pulmonary embolism^[1].

Deep Vein Thrombosis (DVT)

Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, usually in the lower leg, thigh, or pelvis, but it can also occur in the arm^[3]. DVTs usually form in the deeper veins of your body, embedded in the muscles of your legs or arms^[2]. DVT can also develop in large veins if there is a large intravenous central line in the vein^[1].

A DVT that blocks the vein causes inflammation at the site of the blockage and can cause long-term damage to the vein. About half of people with DVT have no symptoms at all. Not all DVTs cause an obstruction, but because they can, they are considered a venous thromboembolic disease. DVTs can also break loose and travel to your lungs, leading to pulmonary embolism^[2].

Pulmonary Embolism (PE)

Pulmonary embolism (PE) occurs when a part of the blood clot breaks off and travels through the bloodstream to the lungs^[3]. In most cases, the blood clot starts in a deep vein in the leg and travels to the lung. Rarely, the clot forms in a vein in another part of the body^[4].

Because one or more clots block blood flow to the lungs, pulmonary embolism can be life-threatening^[4]. A PE restricts oxygen and blood flow to your lungs while increasing blood pressure in your arteries. This causes pulmonary hypertension (high blood pressure in the arteries to your lungs), which in turn can cause heart failure and death^[2].

How Common Is This Condition?

VTE is common. In the United States, as many as 600,000 VTE events occur each year^[1]. According to the Centers for Disease Control and Prevention, the annual incidence is one or two cases per 1,000 persons, and the overall mortality rate is between 60,000 and 100,000 annually^[3].

In the U.S., VTE is the third most common vascular diagnosis, after heart attack and stroke^[2]. Approximately one-third of patients with VTE present with pulmonary embolism, and two-thirds present with deep vein thrombosis. Compared with DVT, PE is more often fatal, has a higher recurrence rate, and is associated with more serious long-term complications^[14].

Signs and Symptoms

It is important to know the signs and symptoms of DVT and PE because VTE can happen to anybody and can cause serious illness, disability, and in some cases, death^[3]. Sometimes people with VTE do not have any symptoms until they have serious complications^[5], and sometimes VTE occurs without any obvious signs, which can make it harder to diagnose^[1].

Deep Vein Thrombosis Symptoms

About half of people with DVT have no symptoms at all^[3]. The following are the most common signs or symptoms of DVT that occur in the affected leg or arm^[3]:

• Swelling
• Pain or tenderness
• Warmth
• Redness or discoloration

If you have any of these signs or symptoms, you should see your doctor as soon as possible^[3].

Pulmonary Embolism Symptoms

You can have a PE without any symptoms of a DVT^[3]. Pulmonary embolism symptoms can vary greatly, depending on how much of your lung is involved, the size of the clots, and whether you have underlying lung or heart disease^[4].

Signs and symptoms of PE can include^[3]:

• Difficulty breathing or sudden shortness of breath (this symptom usually appears suddenly)
• Faster than normal or irregular heartbeat
• Chest pain or discomfort, which usually worsens with a deep breath or coughing
• Coughing or coughing up blood
• Very low blood pressure, lightheadedness, or fainting

If you have any of these signs or symptoms, you should seek medical help immediately. Pulmonary embolism can be life-threatening and needs treatment straight away^[3].

Who Is at Risk?

Almost anyone can have a DVT or PE. However, certain factors can increase the chance of having this condition^[3].

The risk of developing VTE is highest after major surgery, major injury, or during periods of infection and inflammation. This is because blood clots can develop in veins damaged by surgery or injury. Lack of movement after surgery or while traveling long distances can raise the likelihood of blood clotting. Inflammation and serious infection also raise the likelihood of blood clots^[1].

Factors that increase the risk of developing DVT and PE include those associated with^[3]:

• Injury to a vein
• Slow blood flow caused by limited movement
• Certain chronic medical illnesses, older age, family history, and other health factors
• Increased levels of estrogen, a hormone that plays a key role in a female’s reproductive health

Specific risk factors include^[5]:

• Having surgery, especially joint replacement surgery
• Cancers
• Heart diseases
• Lung diseases
• A broken hip or leg bone or other trauma
• Hormone-based medicines, such as birth control pills or hormone replacement therapy
• Pregnancy and childbirth (the risk is highest for about six weeks after childbirth)
• Not moving for long periods, such as being on bed rest, having a cast, or taking a long plane flight
• Age (your risk increases as you get older, especially after age 40)
• Family history and genetics (certain genetic changes can increase your risk of blood clots and PE)
• Obesity

If you have recently had surgery or have other risk factors of VTE, talk to your healthcare provider about your risk and how to prevent blood clots^[1].

How Is It Diagnosed?

It can be difficult to diagnose VTE. If a doctor thinks you have DVT, you should be referred to hospital within 24 hours^[7]. To find out if you have VTE, your health care provider will^[5]:

• Take your medical history, including asking about your symptoms and risk factors for PE
• Do a physical exam
• Likely order some tests, including various imaging and blood tests

Tests Used to Diagnose VTE

Tests used to diagnose or rule out DVT include^[12]:

• D-dimer blood test: D-dimer is a type of protein produced by blood clots. Almost all people with severe DVT have increased blood levels of D-dimer. This test often can help rule out pulmonary embolism.
• Duplex ultrasound: This noninvasive test uses sound waves to create pictures of how blood flows through the veins. It’s the standard test for diagnosing DVT. For the test, a care provider gently moves a small hand-held device (transducer) on the skin over the body area being studied. Additional ultrasounds may be done over several days to check for new blood clots or to see if an existing one is growing.
• Venography: This test uses X-rays and dye to create a picture of the veins in the legs and feet. The dye is injected into a large vein in the foot or ankle.
• Magnetic resonance imaging (MRI) scan: This test may be done to diagnose DVT in veins of the belly (abdomen).

You may have an injection of a blood-thinning medicine called heparin while you’re waiting for an ultrasound scan to see if you have a DVT^[7].

Treatment Options

If you have VTE, you need medical treatment right away. The goal of treatment is to break up clots and help keep other clots from forming^[5]. Not everyone who is diagnosed with VTE needs treatment. If the blood clot needs treatment, your provider will likely prescribe medicine first. You may need a surgical procedure if you cannot take the medicine^[9].

Medicines

Blood thinners (anticoagulants): These medicines keep blood clots from getting larger and stop new clots from forming. Blood thinners reduce the risk of developing more clots^[5]. Conventional blood thinners include warfarin and heparin, but newer blood-thinning medicines called direct oral anticoagulants (DOACs) are also available^[9].

Depending on the blood thinner, you may be given an injection (shot), take a pill, or have an intravenous tube (IV) inserted. You may need to take blood thinners for several months or for a lifetime. The specific amount of time depends on many factors, like the type of blood thinner and the cause of the blood clot^[9].

Blood thinners can cause bleeding, especially if you are taking other medicines that also thin your blood, such as aspirin^[9].

Thrombolytics (medicines to dissolve blood clots): These medicines are used for large blood clots that cause severe symptoms or other serious complications. Because thrombolytics can cause sudden bleeding, they are used only for serious and potentially life-threatening VTE events, such as pulmonary embolism. You will get this medicine through an IV^[9].

Procedures

Catheter-assisted blood clot removal: In some cases, including emergencies, your provider may need to do a catheter-assisted blood clot removal^[9]. This procedure uses image-guided technology to insert a small catheter into the blood vessels to deliver targeted medication directly into the blood clot^[15].

Vena cava filter: A vena cava filter may be used in some people who cannot take blood thinners. Your health care provider inserts a filter inside a large vein called the vena cava. The filter catches blood clots before they travel to the lungs, which prevents pulmonary embolism. But the filter does not stop new blood clots from forming^[5].

Surgery: In rare cases, surgical removal of the blood clot (thrombectomy or embolectomy) may be necessary^[15].

Treatment Duration

Current guidelines recommend anticoagulation for a minimum of three months^[13]. Anticoagulation beyond three months should be individualized based on a risk/benefit analysis^[14].

Preventing Blood Clots

VTE is often preventable^[3]. If you are preparing to go to the hospital for a procedure or have other VTE risk factors, talk with your healthcare provider about a plan for preventing blood clots from forming^[18].

After Surgery

Clotting is one of the body’s natural ways to heal the damage to your blood vessels from surgery. While you wear a cast or stay in bed to heal, the blood circulating in your veins slows because you stop moving as much as usual. This lack of movement raises the likelihood of blood clotting. The chance of developing VTE is highest in the first 3 months after surgery and lowers with time^[18].

Your provider may give you suggestions, including the following, to help prevent VTE^[18]:

• Keep moving: Helping your blood circulate makes it harder for clots to form. Your provider may tell you to move around as soon as possible after surgery and as you heal. If you cannot get up and walk, try to flex and stretch your feet to improve blood flow in your calves.
• Apply pressure: Gentle pressure keeps blood from pooling and clotting. Your provider may talk to you about applying pressure — for example, by wearing a sleeve or boot that periodically fills with air or by wearing compression stockings, which apply more pressure around the ankles and feet.
• Take blood thinner medicines (anticoagulants): Sometimes this preventive therapy starts before surgery, or your provider may prescribe a blood thinner to take during your recovery.

General Prevention Measures

There are things you can do to lower your chance of getting DVT^[7]:

• Stay a healthy weight
• Stay active — taking regular walks can help
• Drink plenty of fluids to avoid dehydration — DVT is more likely if you’re dehydrated
• Do not sit still for long periods of time — get up and move around every hour or so
• Do not cross your legs while you’re sitting
• Do not smoke
• Do not drink lots of alcohol

During Long Journeys

If you’re traveling for 3 hours or more by plane, train or car, there are things you can do during the journey to lower your chances of getting DVT^[7]:

• Wearing loose clothing
• Drinking plenty of water
• Avoiding alcohol
• Walking around when possible

Possible Complications

The most serious complication of DVT happens when a part of the clot breaks off and travels through the bloodstream to the lungs, causing a blockage called PE. If the clot is small, and with appropriate treatment, people can recover from PE. However, there could be some damage to the lungs^[3].

Chronic thromboembolic pulmonary hypertension is a complication that can happen after a PE with a large clot. It can stop blood from reaching the lungs and can be fatal^[3].

One-third to one-half of people who have a DVT will have a long-term complication, called post-thrombotic syndrome (PTS). PTS is caused by the damage the clot does to the valves in the vein. People with PTS have symptoms such as swelling, pain, discoloration, and in severe cases, scaling or ulcers in the affected limb^[3].

Living After a Blood Clot

Life after deep vein thrombosis or pulmonary embolism can be stressful. Recovery can take upwards of several months and you’ll need to make sure you adhere to your doctor’s medication and treatment schedule^[17].

After the initial recovery you’ll also need to take precautions to prevent future blood clots. This is especially important because a history of DVT may increase your risk of another blood clot. If you’ve had a blood clot before — whether in your leg, arm, or lungs — your chances of another one are higher^[17].

One-third of patients with VTE will have a recurrence within 10 years^[3]. Individual risk will depend on the cause of the blood clot. For example, DVT patients who have a genetic mutation that puts them at higher risk of blood clots have a very high risk of recurrent DVT and will need to be on blood thinners for life^[2].

Lifestyle Tips

After you leave hospital, you’ll be encouraged to^[7]:

• Walk regularly
• Keep your affected leg raised when you’re sitting
• Delay any flights or long journeys until at least 2 weeks after you start taking blood-thinning medicine

Exercises like walking or swimming can help you heal after a clot. They boost your blood flow and may make you feel better. If you had a pulmonary embolism, activities that get your heart pumping, like running or dancing, can make your lungs stronger. But talk to your doctor first about how much is right for you^[17].

Important Reminders

Let all your doctors know if you’ve had a blood clot of any kind. And if you take blood thinners, tell your dentist when you make your appointment^[17].

Try not to stay seated for more than 2 hours at a time — get up and walk around regularly. If you had a DVT in one of your legs, don’t cross your legs when you sit down. That position can affect your circulation^[17].