Deep Vein Thrombosis (DVT)
Deep vein thrombosis (DVT) is a blood clot that forms inside a deep vein. It usually happens in the leg. Left untreated, it can break off and travel to the lungs. That complication is called a pulmonary embolism, and it can be fatal.
DVT affects around 900,000 Americans every year. Many cases go unrecognized because the symptoms look like a muscle cramp or minor injury.
Knowing what to look for can save your life.
What Is Deep Vein Thrombosis (DVT)?
DVT is a blood clot that forms in one of the body’s deep veins. These veins sit far below the skin. They carry blood from the legs back up to the heart.
When blood slows down, a vein gets injured, or the blood is too thick, a clot can form. That clot blocks blood flow through the vein. The result is swelling and pain in the affected area.
The real danger is when the clot breaks free. It can travel through the bloodstream to the lungs and cause a pulmonary embolism. That is a medical emergency.
DVT most often affects the lower leg, thigh, or pelvis. It can also occur in the arm, though that is less common.
Symptoms of Deep Vein Thrombosis
DVT does not always cause obvious symptoms. Some people have no symptoms at all. When symptoms do appear, they often affect only one leg.
Common symptoms include swelling in one leg or foot, pain or tenderness in the calf or thigh, skin that feels warm to the touch, redness or skin discoloration, a heavy or aching feeling in the leg, and visible surface veins that look more prominent than usual.
Symptoms can develop gradually. Many people ignore them or assume it is a pulled muscle.
One-sided swelling combined with warmth and redness that does not go away is a clear warning sign. Do not wait to see a doctor.
If you develop sudden shortness of breath, chest pain, a rapid heartbeat, or cough up blood, call 911 immediately. These are signs the clot may have reached your lungs. See warning signs and symptoms and symptoms in women for what to watch for.
Causes of DVT
Three main factors lead to clot formation inside a vein. Doctors call this combination Virchow’s Triad.
Slow blood flow. When blood moves slowly through a vein, it is more likely to clot. This happens during long periods of sitting, bed rest, or hospitalization.
Vein damage. Injury to the inner lining of a vein can trigger clot formation. Surgery, trauma, or inflammation can cause this type of damage.
Increased clotting tendency. Some people have blood that clots more easily than normal. This can be due to genetics, hormonal changes, or certain medical conditions.
Common triggers include surgery, extended bed rest, cancer and cancer treatment, trauma to a limb, and hormonal contraceptives or hormone therapy. Understanding root causes, including endothelial dysfunction in the vessel walls, is a key part of vascular health assessment.
Risk Factors for Deep Vein Thrombosis
Medical risk factors include cancer, heart failure, inherited clotting disorders such as Factor V Leiden, inflammatory bowel disease, a prior history of DVT, and autoimmune conditions that raise cardiovascular risk.
Lifestyle risk factors include smoking, a sedentary lifestyle, dehydration, and being overweight.
Temporary risk factors include long flights or car trips, recent surgery or hospitalization, pregnancy and the postpartum period, and use of birth control pills or hormone replacement therapy.
Pregnancy raises DVT risk significantly. Hormonal changes make blood more likely to clot. The growing uterus puts pressure on pelvic veins and slows blood flow in the legs. The risk stays elevated for up to six weeks after delivery.
Having multiple risk factors at the same time raises overall risk considerably. A person who smokes, takes hormonal contraceptives, and sits for long hours every day faces a much higher combined risk than someone with just one factor.
How DVT Is Diagnosed
If your doctor suspects DVT, they will use one or more of these tests.
Ultrasound is the most common test. It uses sound waves to image the veins and check for clots. It is painless and takes about 30 minutes.
D-dimer test is a blood test that measures a substance released when a clot breaks down. A high level suggests a clot may be present, though it is not specific to DVT alone.
CT venography uses imaging to look at the veins in detail. It is used when ultrasound results are unclear.
Venography involves injecting dye into a vein and taking X-rays. It is rarely used now because ultrasound is so effective.
Most tests are done on the same day. Your doctor may start treatment before all results are back if symptoms are severe. Advanced vascular assessments, including arterial stiffness testing, can help understand your broader cardiovascular picture.
Treatment Options for Deep Vein Thrombosis
Treatment focuses on stopping the clot from growing, preventing it from reaching the lungs, and reducing the risk of future clots.
Anticoagulants (blood thinners) are the main treatment. They do not dissolve the clot, but they stop it from getting larger and allow the body to break it down over time. Common options include heparin, warfarin, and newer oral anticoagulants like rivaroxaban or apixaban. Treatment usually lasts three to six months, sometimes longer.
Thrombolytic therapy uses stronger clot-dissolving drugs in serious cases. It is used when a clot is large and causing severe symptoms. It carries a higher risk of bleeding.
Compression stockings help reduce swelling and improve blood flow in the leg. They are often recommended during and after treatment to prevent long-term complications.
Surgery is rare. A filter can be placed in the large vein in the abdomen to catch clots before they reach the lungs. This is used when blood thinners are not safe for a patient.
The right treatment depends on the size of the clot, its location, your overall health, and your bleeding risk.
Complications of DVT
Pulmonary Embolism
The most serious complication of DVT is pulmonary embolism. This happens when a clot breaks off and travels to the lungs, blocking blood flow.
Symptoms include sudden shortness of breath, sharp chest pain, rapid heartbeat, fainting, and coughing up blood. It is life-threatening and requires emergency treatment.
Post-Thrombotic Syndrome
Post-thrombotic syndrome is a long-term complication. It develops when the valves inside the vein are damaged by the clot. Blood pools in the leg, causing chronic swelling, pain, skin changes, and in severe cases, leg ulcers.
Wearing compression stockings during recovery can lower the risk of developing it.
Other Complications
Untreated or recurring DVT can contribute to ischemic stroke and long-term damage to veins and surrounding tissue. People with coronary artery disease or other vascular conditions face compounded risk when DVT goes unmanaged.
How to Prevent Deep Vein Thrombosis
Most DVT cases are preventable. Small daily habits make a real difference.
Move regularly. Get up and walk every one to two hours during long periods of sitting. Even brief movement helps blood circulate in the legs.
Stay hydrated. Dehydration thickens the blood and raises clotting risk. Drink water consistently, especially when traveling.
Wear compression socks during long flights and car trips. They improve blood flow in the lower legs.
Exercise consistently. Regular physical activity keeps blood moving well and reduces clotting risk over time.
Do not smoke. Smoking damages blood vessels and raises the risk of clots.
For flights over four hours, walk the aisle every hour if possible. Flex and extend your ankles regularly while seated. If you have a history of DVT, ask your doctor whether preventive blood thinners or compression stockings are right for you before traveling.