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Deep Vein Thrombosis (DVT) occurs when a blood clot forms in a vein, frequently in the leg. It can lead to pulmonary embolism (PE), a sudden blockage in a lung artery due to a clot that breaks free and travels from the leg. PE is a potentially fatal condition, so rapid treatment is vital. 

DVT strikes 400,000 Americans yearly, including postsurgical patients and long-distance travelers. Another 200,000 develop PE and nearly one-third of them die.


When a blood clot or thrombus forms in the large veins of the body, usually in the thigh or calf, it can serve as a “roadblock,” disrupting the flow of the blood returning to the heart. This can cause swelling, pain, and serious complications.  


Anyone can be affected, but certain factors increase your risk:

  • Cardiovascular disease
  • Family history of DVT
  • Increased estrogen levels from birth control pills, hormone replacement therapy, or having given birth in the past six weeks
  • Obesity
  • Sitting for long periods of time
  • Injury to the vein from major surgery, fractures, or severe muscle injury

Talk to your doctor about how to reduce your risks.

DVT symptoms

  • Visible swelling of the leg, along a vein, or behind the knee
  • Pain or tenderness in the leg, or fluid collecting in the foot
  • Increased warmth in the affected area 
  • Red or discolored skin 

PE symptoms

  • Unexplained shortness of breath
  • Pain during deep breathing
  • Coughing up blood
  • Rapid breathing or heart rate
  • Symptoms can be “silent” and can mimic heart attack, pneumonia, or even anxiety. 


“Awareness of DVT and PE is the best way to prevent these conditions,” says John Muir Health hematologist Michael Sherman, M.D. Prevention strategies include:

  • Avoiding inactivity, obesity, and smoking
  • Getting out of bed and moving around after surgery or illness
  • Exercising your lower leg muscles during long trips
  • Taking all medicines your doctor prescribes to prevent or treat blood clots
  • Using compression stockings to prevent swelling

Your doctor can help develop a prevention strategy with you.


Many people who experience DVT think that they simply have a cramp, and delay seeking treatment. This is most devastating if the clot goes to the lungs, and causes more serious issues. 

According to Dr.  Sherman, “There are two reasons to move quickly if you suspect you are having a DVT: to get an accurate diagnosis, and to get immediate treatment with a specific blood thinner.” 

He recommends going directly to the ER where diagnostic tests such as ultrasound and venography can be done very quickly. Ultrasound uses sound waves to show blood flowing, and venography uses dye and an x-ray.

If you have symptoms during travel, alert a flight attendant. “You will need to go to an ER for medical attention, to prevent further issues,” says vascular specialist Soo Kim, M.D.


Medical treatment options include injectable anticoagulants or blood thinners in pill form, such as Warfarin, to decrease the blood’s ability to clot and to stop existing clots from getting bigger. Therapy usually lasts three to six months while your body dissolves the clot over time.

 In a newer option, vascular specialists can now remove clots in a minimally invasive way for some patients. Using ultrasound, a vascular surgeon pinpoints the clot’s location, and removes it via a catheter.  

According to Dr. Kim, “Very quickly, blood flow is restored, pain is gone, and swelling subsides. This can eliminate long-term effects, as well.  Outcomes have been excellent.”


If you are planning a trip that lasts longer than four hours, here are ways to reduce your DVT risk:

  • Walk up and down the aisles of the bus, train, or airplane every hour, or if traveling by car stop and walk around
  • Wear loose clothing and compression stockings to aid blood flow
  • Stay well hydrated and avoid alcohol

If you’re at higher risk, your doctor may prescribe medication before you travel.

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