What Is DVT?

What is Deep Vein Thrombosis?

Pulmonary Embolism

Venous thromboembolism (VTE) is a term that encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE).

Deep vein thrombosis (DVT) is the formation of a blood clot (thrombus) within a deep vein. It commonly occurs in the thigh or calf. Deep vein thrombosis can develop after any major surgery. People who have surgery on the legs and hip are especially at risk.

A pulmonary embolism (PE) is a clot that breaks free and travels through the veins. If it reaches the lungs, it can block the flow of blood to the lungs and heart. A pulmonary embolism is a dangerous condition that can even lead to death.

Is DVT a Serious Medical Condition?

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If the clot blocks the flow of blood through the vein, blood can pool and build up at that site. This can lead to repeated swelling and even pain.

Veins have valves that control the flow of blood through them. These valves may be damaged. This could increase the pressure in the veins (venous hypertension).

A blood clot may break free and travel through the veins. If it reaches the lungs, it can block the flow of blood to the lungs and heart (pulmonary embolism, or PE). A pulmonary embolism is a dangerous condition that can even lead to death.

Venous thromboembolism is an important condition to diagnose and prevent. Acute pulmonary embolism causes over 150,000 deaths per year in the United States. Furthermore, patients who undergo total joint arthroplasty are at the highest risk for venous thromboembolism.

What Causes Deep Vein Thrombosis?

A number of things can contribute to clots forming in veins.

  1. Blood that flows slowly through veins (stasis)

    The walls of veins are smooth. This helps blood flow freely and mix with naturally occurring agents (anticoagulants) in the blood that keep the blood cells from clotting.

    Blood that does not flow freely and does not mix with anticoagulants may lead to blood clots. This is why it is important to watch for signs of deep vein thrombosis in people who remain in bed or who do not move for long periods of time.

  2. Coagulation

    Blood thickens (coagulates) around matter that doesn’t belong in the veins. During surgery, matter like tissue debris, collagen, or fats can be released into the blood system. This is why clot formation in the bloodstream is an important consideration after surgery.

  3. Damage to the vein walls

    During surgery, a surgeon must move (retract) tissues, such as muscle, ligaments, and tendons, to reach the area being operated on. Sometimes, this can release naturally occurring substances that promote blood clotting.

  4. Other factors

    There are other factors that may contribute to the formation of thrombi in the veins. These include age, previous history of deep vein thrombosis or pulmonary embolism, cancer, vein disease (such as varicose veins), smoking, estrogen usage or current pregnancy, obesity, and genetic factors.

When Can a DVT Happen?

Total Hip Arthroplasty

Patients are at greatest risk for venous thromboembolism after total hip arthroplasty. Blood vessel obstruction; inactivity after surgery resulting in venous stasis; local trauma to veins that may cause intimal injury; and a hypercoaguable postoperative state may result from surgery or other patient conditions. The risk of venous thromboembolism can be reduced with optimal surgical management at the time of surgery along with specific prophylactic treatment.

Total Knee Arthroplasty

Symptomatic and fatal pulmonary embolism is less common after total knee arthroplasty than total hip arthroplasty.


Deep vein thrombosis is a common complication, especially in trauma patients. Patients having hip fracture surgery are also at significant risk for development of venous thromboembolism. Patients with pelvic trauma, the incidence of deep vein thrombosis is 20% to 60%.

Based on results of contrast venography, the rates of total and proximal deep vein thrombosis are approximately 60% and 27%, respectively, without prophylaxis. The rate of fatal pulmonary embolism is reported to be approximately 3.5% within 3 months after hip fracture surgery.

Factors generally acknowledged to pose a risk for venous thromboembolism in surgical patients include advanced age, history of thromoembolic disease, immobility, smoking, obesity, hypercoagulable states, stroke, and cancer.