Top causes of blood clots in the legs and how to avoid them

Blood Clot: What You Need To Know

Blood clotting, or coagulation, is a process where your platelets and the proteins in your plasma (the liquid part of your blood) work together to form a mass of blood called a blood clot. This can help you prevent excessive bleeding after an injury. Most of the time, your body will naturally dissolve the blood clot as your injury heals.

However, blood clots can also form on the inside of your blood vessels when there's no injury. These types of clots do not dissolve on their own, and they can be dangerous.

This condition, known as venous thromboembolism (VTE), is a serious health condition that can have life-threatening consequences. An estimated 900,000 people in the United States are affected by VTE each year, causing about 100,000 deaths. Knowing the signs and symptoms of blood clots and how to prevent them, as well as seeking treatment early, can help you avoid possible complications.

A blood clot is a mass of blood that forms when the platelets and proteins in your blood stick together. Platelets are cell fragments that typically help your blood to clot. Blood clots help the healing process by stopping the bleeding from an injury. They break down and dissolve as your body heals.

In the case of VTE, blood clots form in veins. These types of blood clots can cause health issues and can even be life-threatening.

Here are some examples of VTEs:

Deep vein thrombosis (DVT): A blood clot deep in a vein in your lower leg, thigh, or pelvis. It can block a vein or cause damage to your leg.

Pulmonary embolism (PE): A blood clot in your lungs that can prevent your other organs from getting enough oxygen. PE sometimes occurs when a DVT breaks off and travels to your lungs. It can cause symptoms like chest pain, difficulty breathing, coughing, coughing up blood, and irregular heartbeats.

Cerebral venous sinus thrombosis (CVST): A rare blood clot that occurs in the venous sinuses in your brain. CVST can cause a blockage and lead to a hemorrhagic stroke (a stroke caused by bleeding in or around the brain).

On average, one person in the U.S. Dies of a blood clot every six minutes. It's extremely important to recognize the symptoms of a blood clot so you can get medical treatment right away if necessary.

The location of the blood clot—such as in your arms, legs, lungs, brain, heart, or kidneys—will determine symptoms and possible complications.

Symptoms of DVT Blood Clots

DVT can be difficult to diagnose because you might not experience any symptoms.

Symptoms include:

Arm or leg swelling

Leg or arm pain or tenderness not caused by an injury

Skin redness that is tender to the touch

Skin that is warm to the touch and swollen or painful

Symptoms of PE Blood Clots

Symptoms of pulmonary embolism vary depending on the clot size, how much of your lung is affected, and any underlying conditions.

Common symptoms include:

Symptoms of CVST Blood Clots

CVST is rare, but recovery depends on early treatment. Get help right away if you experience any of these symptoms:

Get help right away if you experience any of these symptoms:

Severe headache and nausea

Seizure

Difficulty talking or comprehending

Impaired control of one or both sides of your body

Vision problems

Injuries, surgery, medications, and medical conditions are common causes of blood clots. Understanding these causes can help you work with your healthcare provider to minimize your risk as much as possible.

Injury

When you get hurt or are injured, your body forms a blood clot to stop the bleeding. This type of clotting is normal and usually not something to be concerned about. In fact, as your body heals, the blood clot will dissipate and dissolve.

A head injury may induce bleeding and lead to blood clots in your brain. You might need to have surgery to remove these blood clots as well as to relieve any pressure in your brain.

Surgery or Immobility

About 50% of blood clots occur during a hospital stay or soon after surgery. They can develop in damaged veins and they're more likely to occur after inflammation or infection, all of which are associated with injuries and surgeries.

Blood clots also are more likely to occur when you are immobile for an extended period of time, such as when you travel long distances or are on extended bed rest.

Medications

Hormone-based medications that contain estrogen can increase your risk of blood clots. These types of medications are typically prescribed to prevent pregnancy, regulate menstrual cycles, or replace hormones during menopause.

Other medications that can contribute to blood clotting include:

Nolvadex and Soltamox (tamoxifen): A medication used to prevent breast cancer by blocking the effects of estrogen on the body

Contergan and Thalomid (thalidomide): A medication used to treat cancers and skin disorders

Epogen (erythropoietin): A medication used to treat anemia in chronic kidney failure

High Cholesterol

When your blood cholesterol levels are too high—especially low-density lipoprotein (LDL) cholesterol—excess cholesterol can stick to your artery walls. This is known as atherosclerosis. As time passes, these deposits harden and form plaque. This plaque can rupture and trigger the formation of a blood clot in an artery. If this process occurs in your heart or brain, the blood clot can lead to a heart attack or stroke.

Some researchers believe that venous (vein) blood clots can also be associated with high LDL. Venous clots aren't caused by plaques, which only form in arteries. The reason for the connection between venous clots and cholesterol is unclear. Chronic inflammation may play a role, as well as risk factors shared by high LDL and blood clots, like being overweight.

Some researchers theorize that chronic inflammation could be responsible for both high LDL cholesterol and blood clots. In fact, studies have shown that LDL cholesterol can activate your platelets, ultimately leading to blood clots.

Clotting Conditions

Sometimes blood clots occur because you have a condition that causes your blood to clot too easily. These conditions cause overactive clotting, which can lead to bleeding when you run out of platelets.  

Conditions that can cause this excessive clotting include:

Antiphospholipid syndrome (APS): APS is an autoimmune disorder where antibodies called antiphospholipids attack and damage parts of your cells called phospholipids. This damage increases the likelihood that blood clots form. 

Disseminated intravascular coagulation (DIC): DIC is a rare but serious condition that causes abnormal blood clotting. It can occur after an infection or injury.

Thrombotic thrombocytopenic purpura (TTP): TTP is a rare, life-threatening condition that causes blood clots to form in small blood vessels throughout your body. These clots can limit or block blood flow to your brain, kidneys, and heart and prevent them from working properly.

Risk Factors

A number of factors can increase your risk of developing a blood clot. For instance, cancer, pregnancy, and surgery are three significant risk factors. Certain medical conditions and medications can also increase your risk.

Here are some of the most common risk factors for developing a blood clot:

Having obesity

Remaining immobile for extended periods of time

Smoking

Oral contraceptives (birth control pills)

Physical trauma (injury to a vein due to a broken bone or other serious injury)

Surgery

Being over the age of 60

A family history of blood clots

Chronic inflammatory diseases (CIDs), such as multiple sclerosis and rheumatoid arthritis, which cause your body to overreact or attack itself

Diabetes, a condition that affects how your body regulates glucose (sugar) levels

Hypertension (high blood pressure)

High cholesterol

If a healthcare provider suspects a blood clot after reviewing your medical history and doing a physical exam, they may order additional testing to confirm the diagnosis.

Here are some of the tests used to diagnose a blood clot:

Blood tests: One blood test used to diagnose a blood clot is a D-dimer test. This blood test looks for D-dimer in your blood, which is a protein fragment that is made when a blood clot dissolves in your body. This blood test is often used to diagnose a clotting disorder.

Imaging tests: A venous ultrasound is commonly used to look for blood clots, particularly in leg veins. This test is a popular approach if DVT is suspected.

X-rays: Sometimes healthcare providers will use venography to look at your veins or angiography to look at your blood vessels. These tests use a special dye to create clearer images of your veins and blood vessels. They allow healthcare providers to see how your blood is flowing and determine if any clots are interrupting this flow.

Computerized tomography (CT) scans: A CT scan may be used to detect and diagnose a blood clot. For instance, a CT angiography (CTA) scan can be done on the chest, abdomen, pelvis, or head to look at your body's blood vessels and search for a blood clot.

After diagnosing a blood clot, your healthcare provider might refer you to a hematologist. A hematologist is a medical doctor who specializes in blood diseases. The treatment for blood clots largely depends on the type of blood clot, its location, and its severity.

Possible treatments for blood clots include:

Anticoagulants: These blood-thinning medications are used to prevent blood clots from forming, but they do not break up clots you already have. They can be used to prevent the growth of any existing clots.

Thrombolytics: These medications dissolve blood clots. They're usually reserved for more severe clots.

Surgery: Surgery might be necessary to remove a blood clot. For example, a thrombectomy is a technique that removes a blood clot from a blood vessel. Another procedure called catheter-directed thrombolysis involves delivering medication via a catheter (a long tube inserted into your body).

Knowing your risk factors and recognizing the signs and symptoms of a blood clot are helpful in prevention.

Here are some other tips:

Try to get up every hour or so in general. Sitting for long periods of time—whether at work, at sporting events, or while watching TV—can put you at a greater risk for blood clots.

If possible, stand up and move around periodically if you are traveling long distances, are on bed rest, or if you've recently had a serious illness or injury.

Engage in regular physical activity. Aim to exercise at least 150 minutes each week.

Avoid smoking. Smoking restricts your blood vessels, which increases your risk of blood clots.

Maintain a healthy weight.

Healthcare providers also take steps to prevent possible blood clots following surgery—for example, DVT after a total hip or knee replacement. You might take anticoagulation medication before the procedure and wear a compression garment after surgery. Compression garments, including socks, stockings, and sleeves fit very tightly and apply pressure in order to improve circulation.

Blood clots can block blood flow in your veins. Possible complications depend on the location of the blood clot. The most serious conditions that can potentially be attributed to a blood clot include heart attack, stroke, breathing issues, and even death.

Developing a blood clot in your leg or arm during pregnancy increases the risk of a pulmonary embolism. A blood clot during pregnancy also increases the risk of miscarriage, premature labor (labor that begins before 37 weeks), and even maternal death.

A blood clot is a mass of blood that forms to stop your body from bleeding when you are injured. They're an important part of the healing process. However, blood clots can also form even when you haven't been hurt, putting you at risk for a number of potentially serious complications. Many patients with thromboembolism have a condition or a risk factor that puts them at greater risk of blood clots, even if there is no known injury.

Understanding the symptoms of a blood clot and reaching out to a healthcare provider as soon as possible can help you avoid complications. Many blood clots are treatable if diagnosed early. You can also lower your risk by taking preventative steps like moving regularly and managing conditions associated with blood clots.

Surgery And Procedures For DVT

You may already take blood-thinning medications to break up blood clots in your legs that result from your deep vein thrombosis (DVT) condition. But sometimes, drugs alone cannot restore your healthy circulation, and you need surgery. If you have reached that stage, research will make you more comfortable with the procedures that doctors called vascular surgeons or interactive radiologists perform.

Thrombectomy

In this procedure, a doctor may make a cut (incision) in a vein or artery above the clot to remove it. Or, they may insert a thin tube called a catheter into a vein in your groin or arm and thread it through blood vessels to reach the clot. Either way, the doctor may inject a contrast dye into your blood vessel to help pinpoint the clot location. The clot often is in a vein or artery in your arm or leg, but sometimes the surgeon will operate on an organ or other body part.

Usually, a clot must be very large to justify a thrombectomy. In some cases, the doctor will also insert a special balloon attached to the catheter and inflate it to remove any remaining part of the clot. And the doctor may permanently leave a different tube called a stent in the blood vessel to help keep it open.

Your doctor will brief you on potential risks with a thrombectomy, including:

Excess bleeding during the procedure that can be dangerous

Damage to the blood vessel during surgery

Infection

A negative reaction to anesthesia

A clot or fragment finding its way to your lungs and blocking blood flow there

Also, your doctor will tell you about the risk that new clots could form even after a successful thrombectomy.

Before the procedure, you may get certain medical tests like an ultrasound (to measure blood flow in the affected body part), venogram or arteriogram (to get an image of the affected blood vessel), or a computed tomography (CT) scan (to reveal more about the clot).

Your doctor will ask you to stop smoking and to list any prescription or over-the-counter medications you take regularly. You also will be asked about any allergies, health changes, pregnancy, or reaction to anesthesia that could cause problems during surgery.

Continued

In some thrombectomies, the medical team gives you a local anesthetic to numb skin for an incision and shaves hair from that area. During the procedure, an IV tube will deliver an anesthetic, and possibly blood thinner and other medications, into your hand or arm.

After surgery, you may spend several hours in a recovery room under close observation. Then, you could need a day or two in the hospital. Once you go home, you may need to take blood thinners and pain medication for a short time and to wear compression stockings to help prevent clots from reforming. You can expect a number of follow-up appointments with your doctor.

Catheter-Directed Thrombolysis

Your doctor may decide your clot can be handled effectively with a procedure that's less invasive than a thrombectomy, and by dissolving rather than removing the clot. Catheter-directed thrombolysis uses X-ray equipment, a catheter, and special dissolving medications.

Guided by the X-ray camera, the doctor inserts a catheter into a vein or artery and guides it to the area where blood flow is blocked. Next, they inject a contrast dye through the catheter and do a series of X-rays; both actions help pinpoint the clot. The catheter may be left in place for up to 72 hours if it applies clot-dissolving medications. Or, the doctor may use the catheter to position a tiny mechanical device to remove the clot, in a procedure that normally takes about an hour and doesn't require a long hospital stay.

Potential risks of catheter-directed thrombolysis include:

Infection, either during an injection or after the procedure

An allergic reaction to the contrast dye

Damage to a blood vessel

Excess bleeding triggered by blood thinners or other medications

A clot or fragment breaking free and causing harm elsewhere

Kidney damage, especially if you have a kidney condition

Also, your doctor will inform you that sometimes, the catheter tip cannot make it to the clot, or that sometimes, tissue damaged by lack of blood flow cannot be repaired.

Before the procedure begins, you'll have monitors for your heart rate and blood pressure set up. You will get a local anesthetic before an IV needle is inserted. That IV line will deliver a sedative to make you feel comfortable throughout, although you may feel some pressure as the catheter is inserted and warmness from the contrast dye. You may fall asleep due to sedation.

One to 3 days in the hospital, including a day in the intensive care unit, are normal after this procedure. You may need pain medication and more clot-dissolving medication while you recover, and you may wear a compression stocking or sleeve on your leg or arm. Your doctors may prescribe blood thinners for the next 3-6 months. They may also recommend more treatment for clotting or to repair tissue damaged before the procedure, plus a follow-up visit including a physical exam, imaging tests, and bloodwork.

Continued IVC Filter Placement

An inferior vena cava (IVC) filter is a small, wiry device that a doctor may recommend placing in the major vein that carries blood from the lower body back to the heart. Its purpose is to stop clots from finding their way to your heart and lungs.

A doctor will make a small cut in a vein in your groin or neck to insert a catheter. This catheter will take a collapsed IVC filter to your inferior vena cava and then expand it to attach to the blood vessel's walls. Doctors will either recommend leaving the filter in your body permanently or decide to remove it after some time.

Some risks of an IVC filter placement are the same as with the other DVT-related surgeries. But your doctor will address other possible risks, such as:

A filter blocking blood flow rather than clots

A filter coming loose and traveling to your heart or lungs, or piercing the blood vessel

An improperly positioned filter

The procedure normally takes about an hour, and after a few hours of recovery, you may return home the same day (although you will need a driver). You will receive a sedative during the procedure through an IV. If you have pain afterward, it usually can be handled with over-the-counter medication. In the future, you may need to take blood thinners and should expect doctor visits for imaging tests that make sure the filter remains in the right place.

WebMD Medical Reference

Sources

SOURCES:

Johns Hopkins Medicine: "Surgical Thrombectomy."

Mayo Clinic: "Pulmonary Embolism."

NYU Langone Health: "Minimally Invasive Procedures for Deep Vein Thrombosis."

American Academy of Orthopaedic Surgeons: "Deep Vein Thrombosis."

Radiological Society of North America: "Catheter-directed Thrombolysis."

Cardiovascular Diagnosis & Therapy: "Catheter-directed thrombolysis of deep vein thrombosis: literature review and practice considerations."

Society for Vascular Surgery: "Catheter-Directed Thrombolytic Therapy."

Johns Hopkins Medicine: "Inferior Vena Cava (IVC) Filter Placement."

Memorial Sloan Kettering Cancer Center: "About Your Inferior Vena Cava (IVC) Filter Placement."

Stony Brook Medicine: "Inferior Vena Cava Filters."

Society for Vascular Surgery: "Catheter-Directed Thrombolytic Therapy."

© 2023 WebMD, LLC. All rights reserved.

Do Not Miss The Signs Of A Blood Clot

ANDREW ELLSWORTH, MD

The patient was young, healthy and short of breath. She had not been sick recently, other than a minor cough. Her oxygen level was normal and her lungs sounded clear.

Her heart rate was a little fast and she was breathing rather quickly, too. She was anxious about it, but she knew there was more to this than anxiety. Meanwhile, she was taking an antibiotic for bronchitis which did not seem to be helping.

We did some additional tests, some blood work, to look for other possible causes. One test result gave us a big clue: her "d-dimer" was elevated. While not tied to a specific diagnosis, this gave us more reason to keep looking.

We proceeded to get a CT pulmonary angiogram, a special scan of the chest, specifically looking at the vessels that run from the heart to the lungs, looking for a blood clot. Sure enough, that is what it was: a pulmonary embolism.

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The treatment was medication to help thin the blood, which helps the clot to gradually dissolve. She was relieved to know the cause of her symptoms and within days she was feeling better.

Without treatment a pulmonary embolism, or blood clot in the lungs, can be fatal. Thus, early detection and treatment is key. Unfortunately, detecting it may be difficult, especially since the symptoms are often vague and common with numerous other illnesses.

In addition to shortness of breath, coughing, wheezing, coughing up blood or pain with breathing can be symptoms of a blood clot. Another hallmark symptom of a blood clot may be calf pain or swelling.

Unexplained swelling and pain of a limb may indicate a deep vein thrombosis, a blood clot in the leg or arm. Left untreated, a DVT can become larger and may break off and go through the heart to the lung vessels and cause a pulmonary embolism.

A person may be at increased risk of a clot due to a genetic condition, an illness, pregnancy, after surgery, after an injury, because of cancer or because of medications such as birth control pills.

COVID has been a more recent cause. Sometimes a clot happens for no apparent reason. Prolonged travel is also a reason, so on a long drive or flight, take time to stop and stretch your legs. Wearing high compression socks while traveling may also be helpful.

Shortness of breath can be a symptom of numerous ailments, major or minor. No matter the reason, however, please consult your doctor if you are short of breath or have unexplained swelling of an arm or leg. It could be a blood clot.

Andrew Ellsworth, M.D. Is part of The Prairie doc team of physicians and currently practices family medicine in Brookings, south Dakota. Follow The Prairie doc at www.Prairiedoc.Org and on Facebook featuring On Call with the Prairie doc a medical Q&a show based on science, built on trust for 21 seasons, streaming live on Facebook most Thursdays at 7 p.M. CT.

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