Deep vein thrombosis (DVT) occurs when a blood clot develops in a vein and begins to block the blood flow back to your heart. It often occurs in the lower leg, thigh or pelvis, but can also develop in the arm.

What makes a DVT so dangerous is that a part of this clot can break off and travel through the vein, through the heart and into the lungs. The DVT then becomes a pulmonary embolism (PE), which can stop blood from reaching the lungs—if the clot is big enough, you die.

In most cases, the DVT is small and limited to one area. Regardless, a blood clot of any size can break off and be potentially deadly.

Each year DVT/PEs kill more than 300,000 people in the U.S.—more than HIV and breast cancer combined. However, DVT can be treated and PEs prevented if discovered early.

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Signs & Symptoms

It is important to know the signs of a DVT so that you can seek medical help immediately:

• Swelling
• Pain
• Tenderness
• Discoloration or redness of skin
• Warm skin

You can also develop a PE without showing DVT symptoms. You should go to the hospital immediately if you have these symptoms:

• Difficulty breathing
• Faster than normal or irregular heart beat
• Chest pain or discomfort, which usually worsens with a deep breath or coughing
• Coughing up blood
• Very low blood pressure, lightheadedness, or fainting

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Risk Factors

What makes this so scary is that half the time, people show no symptoms of a DVT at all. It is therefore important to know what causes a DVT, and also know what you can do to prevent a DVT from happening in the first place.

Anyone can have a DVT, but your odds increase with each risk factor present:

• Sitting for long periods without moving (long plane flights and car rides)
• Birth control pills (or other increases in estrogen, including pregnancy and HRT)
• Smoking
• Surgery
• Obesity
• Cancer
• Heart and lung disease
• Genetic clotting disorders
• Age > 40
• Previous history of DVT/PE in you or your family