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A concerning potential blood clot is spotlighted on a person's leg.

What Are the Symptoms of Deep Vein Thrombosis?

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By Editorial Team

2 min read

Deep vein thrombosis (DVT) is a blood clot. It develops deep inside veins that have slower blood flow.1-2 They generally form in the lower leg but can also develop in the thigh or other parts of the body.1 DVTs often resolve on their own. But if a part of a blood clot breaks loose it can cause a potentially dangerous problem called a pulmonary embolism (PE).2

A PE is a DVT complication that is caused by a blockage in one of the pulmonary arteries of the lungs. A piece of a blood clot breaks away and travels from the legs through the bloodstream to the lungs. DVT and PE are common, developing in around 1 in 1,000 people.1,3 Together, they follow heart attack and stroke as the third most common cause of death from cardiovascular disease.1

Symptoms

A DVT sometimes has physical symptoms and other times is symptom-free, called “silent”.4 To evaluate the likelihood of a DVT a doctor will ask questions about your general health and recent medical conditions, perform a physical exam, and do a thorough medical history. The most commonly reported symptoms are pain, redness, and swelling.3

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While performing a physical exam your healthcare team will look for warmth, tenderness, or pain when the foot is flexed. Pain commonly begins in the calf, feeling like a cramp or soreness.4 They also evaluate the presence of swelling (limb edema), typically in the affected leg or body part.4 Along with the physical exam, doctors diagnose DVT using blood and imaging tests.5 Ultrasound can determine the size, severity, and location of the blockage. This can help the healthcare team decide on the course of treatment that is right for each person.3

Staging

The severity of DVT is classified into 4 categories:1,3

  • Provoked: caused by something specific like surgery, oral contraception, trauma, immobility, obesity, or cancer
  • Unprovoked: has no known cause or reason for developing
  • Proximal: occurs closer to the center of the body and more likely to lead to complications such as PE
  • Distal: occurs below the knee

Risk factors

Risk factors can be variable. Conditions that can cause your blood to clot more easily include surgery or trauma, long-term immobility, congestive heart failure, varicose veins, inflammatory bowel disease, obesity, older age, oral contraception, and a prior history of DVT.3 A tumor or even pregnancy can place pressure on a vein compressing it and slowing the flow of blood.3 When you sit or lie still for a long time the muscles in your calves don't contract. Normal contractions help circulation. Blood clots can form when circulation is reduced.4

DVT risk factors are evaluated by elements in Virchow’s Triad:1,3,4

  • Venous stasis: reduced blood flow due to sitting for too long, extended bed rest, paralysis, general anesthesia, surgery, stroke, or long-haul flights
  • Vascular injury: damage to veins caused by trauma, surgery, IV drug abuse, or previous DVT
  • Hypercoagulabilityincreased risk of clotting due to a medical condition or inheriting a blood clotting disorder

Growing older is also associated with an increased risk for clots (thrombosis). Although there is no one clear reason, it seems as they age, more people are overweight, are more frequently sick or have other preexisting medical conditions that can cause them to experience longer periods of immobility.1

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