Risk in the Veins

Blood clots. That’s a good thing when you cut yourself, but blood can also clot inside the blood vessels, and that can cause serious, sometimes devastating, health problems. Blood clots form when something slows or changes the flow of blood in the veins. A stationary blood clot that forms in one part of the body is a thrombus, then if it moves through the bloodstream until it lodges in a narrow vessel and blocks the flow of blood, is called an embolus. An embolus in a coronary artery can cause a heart attack, in a cerebral artery, it can cause a stroke.

When these blood clots form in the veins it is called venous thromboembolism (VTE). There are two related, and potentially life-threatening, conditions that come under the category of VTE, deep vein thrombosis (DVT) and pulmonary embolism (PE). When they occur, they demand immediate medical attention.

DVT and PE

Deep vein thrombosis affects up to 2 million people in the U.S. and happens when a clot forms in a vein deep in the body, as opposed to a vein that runs close to the body’s surface.

DVT usually occurs in the leg, mainly affecting the large veins in the calf and thigh, usually on one side, not both.

About half of people experiencing DVT don’t show outward signs or symptoms. When symptoms do occur, they show up in the leg that has a clot.

Pulmonary embolism occurs when a clot due to DVT makes its way into a lung artery causing a blockage that can permanently injure the affected lung, lowering the blood’s oxygen level and potentially damaging other organs by starving them of oxygen. Blood clots that travel to the lungs are more likely to have formed and broken away in the thigh rather than in the lower leg or other parts of the body.

About half of people experiencing DVT or PE will not exhibit symptoms. When symptoms of DVT do show up, they may include:

  • Changes in skin color (redness)
  • Leg pain or tenderness, especially in the calf
  • Leg swelling (edema)
  • Skin that feels warm to the touch

Symptoms that may present for PE include unexplained shortness of breath, rapid breathing, chest pain (may be worse upon deep breath), rapid heart rate, lightheadedness/ passing out or coughing up blood.

Get medical attention immediately if you have these signs or symptoms. DVT and PE are serious, potentially life-threatening conditions that demand treatment to prevent further complications.

The Centers for Disease Control and Prevention estimates that there are 300,000 to 600,000 VTE events annually in the United States

Risk Factors

VTE is an equal opportunity condition and can affect people of either gender, all ages, races and ethnicities. But some risk factors for VTE are stronger than others. Increasing age (from 40 on) means increased risk. Experiencing surgery, major trauma, fractures of the hip or leg, also carries strong risk. Other independent risk factors include:

  • Active cancers and chemotherapy
  • Prior superficial vein thrombosis
  • Infection
  • Varicose veins
  • Inherited thrombophilia (a condition that tends to make the blood clot more easily)
  • Kidney disease
  • Prolonged immobility such as hospital or nursing home confinement or leg paralysis due to, for example,stroke or spinal cord injury

And among women:

  • Use of oral contraceptives
  • Pregnancy/postpartum period
  • Hormone therapy

Any of the factors below alone may not justify preventive measures for VTE, but a combination of two or more may be cause for action and may have an effect on the length and type of treatment someone receives:

Prior VTE — People who have had a previous episode of VTE have a high risk of recurrence. In one study, patients with a history of VTE were eight times more likely to develop a new episode during a high-risk period, such as surgery or serious illness, than patients without such a history.

Age — Patients older than 40 are at higher risk, and that risk doubles with each subsequent decade.

Cardiac or respiratory failure

Immobility — Prolonged immobility like on very long flights combined with other major risk factors increases the chances of VTE.

Oral contraceptives — Women who use estrogens for contraception or menopause and men receiving estrogen therapy for prostate cancer are at increased risk for VTE.

Some inherited or acquired blood conditions, such antiphospholipid antibody syndrome.

Being pregnant, or having had a baby recently puts a woman at greater risk of developing a blood clot.

Her risks increase when the following also apply:

  • Has experienced previous blood clots
  • Genetic predisposition to blood clots
  • Obesity
  • Prolonged immobility, such as bed-rest or long distance travel
  • Multiple births
  • Increased maternal age
  • Other illness, such as cancer and serious infection


Diagnosis is done by assessment — a healthcare professional gathers information about a person’s medical history, age, medications and specific lifestyle factors. A Doppler ultrasound may be performed on the legs and certain blood tests that detect a greater chance of blood clotting may be performed. Additional testing with CT angiography (a test used to see arteries and veins throughout the body) may be done if PE is suspected.

Preventive Treatment for VTE

Those determined at risk of VTE based on medical assessment may receive treatment designed to prevent clots from forming. This treatment may include approaches such as:

  • Anti-clotting, blood-thinning medications
  • Wearing compression stockings or using an intermittent compression device that helps keep blood from pooling in the deep veins
  • Being instructed to move around or do foot/leg exercises when immobile for long periods.

Treatment for DVT

When deep vein thrombosis is diagnosed, it is potentially life-threatening and requires immediate medical attention. Most importantly the medical team wants to stop the clot from getting bigger, keep the clot from breaking off and travelling into the lungs, and doing everything possible to keep another clot from forming. Treatment usually includes blood thinners to break up existing clots and prevent new ones.

  • Anticoagulants. For example, injectables such as heparin or low-molecular-weight heparin, or tablets such as apixaban, dabigatran and rivaroxaban, edaxaban and warfarin.
  • Equipment such as compression stockings and air compression cuffs and garments for the legs, calves, arms or chest that fill with compressed air and help increase blood flow. 
  • Thrombolytic therapy using drugs such as a tissue plasminogen activator, which is a clot-dissolving enzyme.

In rare cases, when medicines don’t work, surgery may be needed. It may involve placing a filter in the body’s largest vein to prevent blood clots from traveling to the lungs or removing a large blood clot from the vein or injecting clot-busting medicines.

Pulmonary embolism is the most common preventable cause of death among hospital patients. The potential public health benefit of preventing VTE is substantial. Data from randomized trials involving general surgical patients suggest that adequate prevention measures in high-risk patients can prevent VTE in one of 10 patients and save the life of about one of 200 patients.

The good news is that hospitals are doing a better job of managing the condition. New research has focused on development of noninvasive diagnostics such as ultrasound enhanced techniques and molecular imaging methods.



This information is provided as a resource to our readers. The tips, products or resources listed or linked to have not been reviewed or endorsed by the American Heart Association.

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