Venous blood clots (including DVT)

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Nearly 6 million Americans have a blood clot in their veins (also called venous thrombus, venous thrombosis, or vein thrombosis). When the clot develops in a vein deep within the leg, it is called deep vein thrombosis (DVT). The condition can be life threatening if the clot breaks loose from the vein and travels to the lungs, where it can completely block blood flow.

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What causes a venous blood clot?

Blood clots in the veins are usually caused by slowed blood flow to the legs and feet, which can cause the blood to clot. Venous blood clots may also be caused by damage to a vein from an injury or infection. Blood flow may be slowed because of physical inactivity—being confined to a bed or having an inactive lifestyle. Some people have slowed blood flow after sitting for a long time, such as on a long plane ride. This is why the condition is sometimes called “economy-class syndrome.”

Other factors that lead to slowed blood flow in the legs and feet include smoking, heart disease, diabetes, high blood pressure, and certain tumors. The use of certain hormones, particularly estrogen, and pregnancy have been shown to increase the risk for blood clots in the legs. Genetic disorders may also increase a person’s risk.

What are the symptoms of venous blood clots?

Blood clots that happen in the veins close to the surface of your skin may cause mild swelling, tenderness, and redness. Symptoms of deep venous clots may include

• Swelling of your ankles or calves.
• Tenderness, swelling, redness, and warmth around the affected area.
• Pain when your foot is raised upward.

How are venous blood clots diagnosed?

Doctors can usually tell if you have a venous blood clot by pressing on a part of your leg. If needed, the veins can be viewed by using ultrasound, which uses sound waves to create an image of the vein on a screen. Clots above the knee may be identified by using a blood pressure cuff around your leg to measure blood flow (plethysmography). Deep venous blood clots in areas other than the leg may be impossible to detect by these methods. Diagnosis may require special techniques such as blood-clotting tests, x-rays of the veins, magnetic resonance imaging (MRI) and computed tomography (CT) scanning.

How are venous blood clots treated?

Treatment depends on the cause of the blood clot. In most cases, a blood-thinning or anticoagulant medicine will be given. You will need to stay in bed and keep your legs raised for 3 to 5 days. Moist heat and medicines can ease the swelling and pain.

For those who have had a clot in the lungs or those who cannot take anticoagulants, a catheterization procedure may be needed to insert a filter in a vessel to prevent clots from reaching the lungs.

How Travelers Can Avoid Deep Vein Thrombosis (DVT)

Travelers sitting for long periods on airplanes or in cars have an increased risk of developing deep vein thrombosis, or DVT.

People with DVT have a blood clot in a vein deep within their leg. The clot is usually caused by slowed blood flow to the legs and feet, so sitting for long periods can increase the risk of DVT.

The easiest way to prevent DVT is to keep moving. If you are taking a long road trip, stop the car every 2 to 3 hours and get out and walk around, or try flexing your ankles and your leg and hip muscles while you are seated.

Dehydration can thicken your blood and increase the risk of clots. Drink lots of water while you are traveling and avoid caffeine and alcohol which cause dehydration. During a layover or when you reach your destination, walk quickly to restore circulation in your legs.

By following these simple tips, you can lower your risk of DVT.

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Article Info

Causes, Warning Signs, Treatment, and Prevention of Deep Vein Thrombosis

Written by Dean Shaban

Medically Reviewed by Poonam Sachdev on June 14, 2023

• What Is Deep Vein Thrombosis (DVT)?
• DVT Symptoms
• DVT Causes
• DVT Risk Factors
• DVT Tests and Diagnosis
• DVT Progression
• DVT Treatment
• DVT Health Disparities
• DVT Complications
• Living With DVT
• DVT Prognosis
• Can I Prevent DVT?
• Takeaways
• More

If blood moves too slowly through your veins, it can cause a clump of blood cells called a clot. When a blood clot forms in a vein deep inside your body, it causes what doctors call deep vein thrombosis (DVT). This is most likely to happen in your lower leg, thigh, or pelvis. But it can occur in other parts of your body, too.

DVT can lead to major health problems. In some cases, it can be fatal. That’s why if you think you have one, you must see a doctor right away.

Not everyone with DVT shows symptoms. But you might notice any of the following:

• Leg or arm swelling that comes on without warning
• Pain or soreness when you stand or walk
• Warmth in the area that hurts
• Enlarged veins
• Skin that looks red or blue

If a blood clot breaks free and moves through your bloodstream, it can get stuck in a blood vessel of your lung. Doctors call this a pulmonary embolism, or PE. It can be fatal.

Some people don’t know they have DVT until this happens. Signs of PE include:

• Shortness of breath
• Chest pain that’s worse when you take a deep breath
• Coughing up blood
• Higher heart rate

Learn more about DVT symptoms

The causes of DVT include things that keep blood from:

• Flowing through your leg, thigh, or pelvis
• Clotting correctly

This usually happens as a result of damage to one of your veins due to:

• Surgery
• Inflammation
• Infection
• Injury

Many things can raise your chances of getting DVT. Here are some of the most common:

• Age. DVT can happen at any age, but your risk is greater after age 40.
• Sitting for long periods. When you sit for long stretches of time, the muscles in your lower legs stay still. This makes it hard for blood to circulate, or move around, the way it should. Long flights or car rides can put you at risk.
• Bed rest. When you’re in the hospital for a long time, this can also keep your muscles still and raise your odds of DVT.
• Pregnancy. Carrying a baby puts more pressure on the veins in your legs and pelvis. What’s more, a clot can happen up to 6 weeks after you give birth.
• Obesity. People with obesity – that’s a body mass index (BMI) of 30 or higher – are at a higher risk. BMI measures how healthy your weight is based on how tall you are.
• Serious health issues. Conditions like inflammatory bowel disease, cancer, and heart disease can all raise your risk.
• Certain inherited blood disorders. Some diseases that run in families can make your blood thicker than normal or cause it to clot more than it should.
• Injury to a vein. This could result from a broken bone, surgery, or other trauma.
• Smoking . This makes blood cells stickier than they should be. It also harms the lining of your blood vessels. This makes it easier for clots to form.
• Birth control pills or hormone replacement therapy. The estrogen in these raises your blood’s ability to clot. (Progesterone-only pills don’t have the same risk.)
• Infection. When in your blood, veins, or elsewhere, it could lead to DVT.
• Inflammation. This could be due to infection, surgery, injury, or some other root cause.
• High cholesterol.

In some cases, neither the cause nor the symptoms of DVT are very clear, so tell your doctor about any changes you notice if you are at higher risk for DVT.

How many people get DVT? 

DVT symptoms can be hard to find and often go unnoticed. So it’s hard to estimate the number of diagnoses . But it’s thought that about 8 in every 10,000 people get DVT every year. And lower-leg DVT happens  in every 1 in 1,000 people. But these numbers actually could be higher.

Your doctor will first do a physical exam of your leg and lower body areas to check for symptoms. If there is any swelling, tenderness, or change in skin color, they will likely want to run some tests to see if you have DVT. Such tests include:

• Duplex ultrasound. This is the standard test for DVT. Your doctor will run an ultrasound to scan parts of your body for clots in your veins. An ultrasound scanner sends sound waves to create images showing how blood flows through your veins.  If your doctor finds a clot, they may want you to come back for more ultrasounds to see if it has grown or if there are any new ones.
• D-dimer blood test. Most people with bad DVT will have D-dimer in their blood, It’s a type of protein that comes from blood clots. Your doctor will do a blood test to see whether you have high levels of D-dimer.
• MRI. MRIs are usually done for DVT in the lower abdomen or belly area. They are not standard for the more common forms of DVT.
• Venography. This test is rarely done because it is so invasive. Your doctor will inject dye in your veins and take an X-ray to see if the dye is flowing properly through your veins. It can let your doctor to see if you have any clots. Other tests, like an ultrasound, are done first.

Find out more about DVT tests and diagnosis

DVT can progress as your symptoms get worse. Signs of acute DVT include: 

• Pain in your leg or arm. It could be swollen and feel warmer than it normally does. 
• You may notice a change in skin color. It might be red. If you have a darker skin tone, this may be harder to see. 
• A bad headache that can come on suddenly. You might also have seizures.
• Bad belly pain (if blood clots are in your abdomen)

If you are breathless or have chest pain, this can be a bad progression in your DVT. You might feel lightheaded or faint. If this happens, you need medical care right away. These could be signs of a pulmonary embolism (PE), when the clot is going into your lungs. PE can be fatal if it’s not caught early enough.

Your doctor will want to stop the blood clot from getting bigger or breaking off and heading toward your lungs. They’ll also want to cut your chances of getting another DVT.

This can be done in one of three ways:

Medications for DVT

Blood thinners are the most common medications used to treat DVT. They cut your blood’s ability to clot. You may need to take them for 6 months. If your symptoms are severe or your clot is very large, your doctor may give you a strong medicine to dissolve it. These medications, called thrombolytics, have serious side effects like sudden bleeding. That’s why they’re not prescribed very often.

Procedure for DVT

Inferior vena cava (IVC) filter. If you can’t take a blood thinner or if one doesn’t help, your doctor may insert a small, cone-shaped filter inside your inferior vena cava. That’s the largest vein in your body. The filter can catch a large clot before it reaches your lungs.

Home remedies for DVT

Compression stockings. These special socks are very tight at the ankle and get looser as they reach your knee. This pressure prevents blood from pooling in your veins. You can buy some types at the drugstore. But your doctor might prescribe a stronger version that an expert can fit for you.

Know more about the latest DVT treatments

Research shows that Black people are more likely to have DVT than White people. But they’re just as likely or less likely to have PE. 

Studies show that people with what’s known as “metabolic syndrome” are at greater risk of having a DVT event. Metabolic syndrome is a condition linked to a group of other conditions, such as obesity, high blood sugar, high cholesterol, and high blood pressure.

Black people, and especially Black women, tend to have metabolic syndrome more often than people of other racial groups. This can increase their chances of having DVT.

Up to half of people with DVT will have long-term complications because of damage to the leg vein (post-thrombotic syndrome) where blood remains too long (chronic venous insufficiency). You may notice pain, swelling, and redness, which can lead to open sores if you don’t get early treatment. In time, this can make it harder to do daily activities and even walk.

The biggest worry for a blood clot is a DVT that breaks off and causes a pulmonary embolism (see above). If the clot isn’t too big and you get the right treatment fast enough, you may recover from this, though there may be some long-term lung damage.

About a third of people who have had a DVT or PE have a higher risk of another incident.

Living with DVT can be very manageable if you stick to a good routine, eat well, and budget enough for out-of-pocket costs. It’s also important to stay aware of your mental well-being during and after a DVT.

DVT diet

While it is always good to stick to a well-balanced diet, healthy eating is especially important if you have DVT. Inflammation is known to make the risk of blood clots higher. Here are some tips for eating to lower inflammation:

• Try to include plant-based foods like fruits, veggies, nuts, and whole grains.
• Olive oil and canola oil are good subs for butter.
• If you’re going to flavor your food, try herbs and spices instead of salt.
• Red meat is fine, but try to keep it to no more than two to three times a month.
• It’s good to eat fish at least twice a week.

DVT costs

Research shows that people with DVT lose, on average, 57 short-term disability days at work and 440 long-term disability days. The out-of-pocket cost per year is about $2,500, including medical and pharmacy expenses. It may be more or less, depending on your insurance or if you are uninsured.

Managing DVT

After a DVT, you can slowly get back to your normal activities. 

• If you sit for a while, it’s good to stand up and walk for a few minutes every hour. This is especially true for road trips or long flights.
• If you’re sitting for a long time (like at work), exercise your calf muscles.
• Always wear compression socks as prescribed by your doctor. This will help with swelling.
• Try not to do anything that could cause a serious injury.
• Drink plenty of water.

DVT and mental health

The trauma of going through a blood clot can cause mental health issues for you. These may include:

• Anxiety
• Depression
• Posttraumatic stress disorder (PTSD)

If you have or think you may be having any of these or other mental health conditions as a result of your DVT, reach out to a mental health professional for one-on-one or group therapy.

Since a DVT can take up to a year to break apart, your doctor will likely want to do more ultrasounds after the first one to see if it has spread or gotten worse. 

Always take your blood thinners as prescribed and wear compression socks until your doctor tells you it’s OK to stop. You might need more blood tests to check that you have the right dosage of medications as your DVT gets better or worse.

Can DVT be cured?

Yes. With the proper treatment and attention, your blood clot can come apart over time.

Simple lifestyle changes may help lower your odds of getting one. Try these simple tips to keep your blood circulating the way it should:

• Take care of yourself. Stop smoking, lose weight, and try to be active.
• Get regular checkups. And if your doctor has prescribed a medicine to control a health problem, take it as directed.
• Don’t sit for too long. If you’re traveling for 4 hours or more, take breaks to flex and stretch your lower leg muscles. If you’re on a flight, walk up and down the aisle every hour. On long car drives, pull over every 2 hours to stretch. Wear loose-fitting clothes, and drink plenty of water.
• Plan surgery after-care. Talk to your doctor about what you can do to prevent DVT after surgery. They might suggest you wear compression stockings or take blood thinners. You’ll also want to get out of bed and start moving around.

Deep vein thrombosis can be managed  and go away if your doctor finds and treats it early enough. With a healthy diet, meds, compression socks, and enough exercise, you can live a full life during and after your DVT. Talk to your doctor right away if you think you might have DVT.

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Causes of thrombosis and inflammation of a thrombus

Thrombophlebitis is an inflammation of a thrombus located in the lumen of a venous vessel. The disease is a vicious circle: inflammation of the vein contributes to the increase in blood clot, and the processes occurring inside the blood clot increase inflammation.

The main cause of vein thrombosis is varicose veins. There are other factors that can cause complete or partial blockage of the venous vessel. All of them can cause life-threatening complications that are difficult to treat. It is best to know the possible causes of the disease, to prevent them.

If a superficial vein is affected, thrombophlebitis is called superficial. When a deep vein is blocked, thrombophlebitis will be called deep. Often, the process begins with superficial vessels, and then goes into the deep vein system.

Both types of disease, regardless of the cause of thrombophlebitis of the lower extremities, are complicated by chronic venous insufficiency. It, progressing, is manifested by darkening of the skin, edema, poorly healing trophic ulcers. The most dangerous complication is the separation of a blood clot with its subsequent entry into the pulmonary artery system or into the cerebral vessels. But if the treatment of thrombosis and thrombophlebitis was started on time and taking into account the cause of the disease, such consequences can be avoided.

Causes of pathology

Doctors name the following causes of thrombophlebitis. These are:

• Varicose veins of the lower extremities, in which the blood flow in the dilated areas is so slowed down that all the conditions for thrombosis occur. This cause accounts for 70% of all superficial thrombophlebitis.
• Injury to the venous wall. Superficially located veins can be injured by impact, friction with bone fragments, and falling. Also, their puncture and catheterization is considered an injury, which is also carried out on the legs. In response to injury to the wall, its components are activated, which cause the formation of a thrombus in the damaged area.
• Prolonged immobilization, especially due to the need to consolidate the fracture. While the deep veins continue to provide outflow from the limbs, the superficial ones are partially compressed by plaster, blood flow slows down in them, and as a result, a blood clot forms.
• Condition after treatment of varicose veins with sclerotherapy.
• Chronic asymptomatic carriage of bacteria when they are in the bloodstream and can inflame existing blood clots.
• Clotting diseases.
• Increased blood estrogen concentration.
• Vasculitis, including lupus.
• Pancreatic, lung, stomach cancer causing migratory thrombophlebitis.
• Increase in the level of homocysteine ​​in the blood.
• Diseases of the liver in which the level of heparin in the blood decreases.
• Homocystinuria.
• Antiphospholipid syndrome.

The main cause of deep vein thrombosis in the lower extremities is called varicose veins. This condition develops as a complication of superficial thrombophlebitis, when a thrombus grows in the direction of the communicating veins (connecting the superficial system with the deep one), and, destroying their valves, breaks into the deep veins.

When smoking, taking contraceptives, obesity, as well as anomalies of the vascular wall, the risk of thrombophlebitis increases several times.

causes and main symptoms

Thrombosis scares everyone, and rightly so. Venous thrombosis is dangerous when a thrombus breaks off, migrates through the veins to the heart, passes through the heart and embolism – blockage of the pulmonary artery. This is a dangerous condition that can not only lead to serious complications, but also to death.

Thrombosis is the formation of a thrombus, that is, a blood clot, on the vessel wall. Such blood clots can either completely block the vein or partially.

It is deep vein thrombosis that poses the greatest danger, as it can lead to thromboembolism. While thrombosis of the veins of the upper extremities almost never leads to thromboembolism.

For the formation of a blood clot in a vein, several conditions are necessary, sometimes even one is enough. In medicine, there is a Virchow triad, which describes the main causes of blood clots in a vein.

1. Deceleration of blood flow. A good example is a long flight, when a person sits motionless for a long time with bent legs. This situation leads to stagnation of blood, which contributes to thrombosis in deep veins. That is why it is important to wear compression stockings during air travel, which will just prevent blood from stagnating and forming a blood clot.

3. Violation of the properties of blood. This includes increased blood clotting, that is, its thickening. This change in blood can be caused by dehydration, so drinking enough water is very important.

For the formation of blood clots, one or all three factors may be sufficient. For example, consider a situation where all three factors are involved. Broken leg.

Therefore, with fractures of the lower extremities, the risk of thrombosis increases significantly. However, there are situations when blood clots form for no apparent reason.

Thrombosis can be localized in different veins. Saphenous vein thrombosis is characterized by symptoms that can be diagnosed visually – this is skin redness, inflammation and induration, most often in those vessels that are prone to varicose veins. Deep vein thrombosis requires a serious diagnosis, as it can be asymptomatic. However, he poses a threat.

But still, deep vein thrombosis has three characteristic symptoms, the presence of which allows us to speak with almost 90% certainty about the fact of thrombosis.

The main symptom of deep vein thrombosis is swelling. They can be expressed to varying degrees, depending on which vein the thrombus is in – in a large or in a small one. Most often, edema in thrombosis is asymmetric – it rarely occurs on two legs at once. Usually it is localized only on one limb. If your legs have been swollen for 3 years, then it is unlikely that a fresh blood clot can be suspected during the diagnosis. With thrombosis, swelling is usually sudden and acute, accompanied by pain.

Why does swelling of the leg appear with thrombosis? This is due to the fact that fluid seeps through the wall of the vein. The fluid should move towards the heart, but because of the thrombus it cannot rise, therefore it looks for a way out through the vessels, getting into the subcutaneous fat and, accordingly, giving edema.

As a rule, edema is localized in the lower third of the lower leg, but if blood clots form at the level of the femoral vein, the entire leg will swell.

The second sign of a deep vein thrombus is pain. Most often, pain occurs in the lower leg and in the popliteal region, depending on which vein is thrombosed. Pain in the thigh area almost never bothers patients, even though a blood clot can also be in the femoral vein.

Pain, like swelling, is sudden and sharp. It can be described as bursting or pulling. It occurs for no apparent reason, that is, not due to injury or sprain. Sometimes a person may even limp while walking, as the pain of a blood clot increases during movement.

The change in skin tone is due to the fact that the blood in the vein cannot flow into the heart area, as it should, but seeps through the walls of the vessel, enters the subcutaneous fat, causing edema, and the edema already provokes a change in skin color.

For the diagnosis of thrombosis, there are additional symptoms that are named after those specialists who discovered these symptoms.

This symptom was first described by the American surgeon Homans, after whom it is named.

The patient needs to take a sitting or lying position and stretch the legs. Then, with an effort, pull the feet towards you. With such a movement, in the presence of a blood clot, pain occurs on the back surface of the lower leg of the affected leg.

To determine the presence of a blood clot, you will need a cuff from a tonometer. It must be worn on the lower third of the leg or above. When creating pressure from 60 to 150 mm Hg. Art. in the presence of thrombosis, palpable pain appears.

It is necessary to squeeze the lower leg in the transverse direction of the calf muscle. There will be no pain with such compression. But with compression in the anteroposterior direction, in the presence of a blood clot, pain occurs.

Not all of the symptoms described are 100% likely to indicate thrombosis, but they allow you to suspect it and begin further examination.