Deep Vein Thrombosis – Clots in Your Veins Which Can Travel To Your Heart and Lungs

Danger level: High

What is it?

Deep vein thrombosis (DVT for short) is a blood clot (or thrombus in Greek) that forms in a deep vein in the body.

Who gets it?

There are a few risk factors for developing DVT:

  1. Conditions that cause the blood to move slower– For example if you are bedridden for a long time or paralyzed, or if you sit in an airplane for a prolonged time (usually for more than 8 hours).
  2. Injury to our blood vessels: This can happen after a trauma or after a major surgery (such as orthopedic surgeries).
  3. A propensity for clotting – In some people, clots can form more commonly than in others. This includes people with blood disorders which can cause this, as well as women taking contraceptive pills (and those taking hormones after menopause), and it can also happen after taking other types of drugs.
  4. Cancer – Can raise your risk of developing DVT.
  5. Pregnancy
  6. People who have had it before – Are more prone to developing DVT again.


Oral contraceptive pills. They can cause DVT. Photo by Gnarls Monkey.

What causes it?

Our body has a clotting system. This is the system that’s responsible for the clot that forms when you are wounded. Platelets (a type of blood cell) in our blood aggregate in the area of the wound, and along with other materials in the blood form the clot. Usually in our body there is a balance between the system that forms clots and systems that prevent clots from happening or dissolve them when they do.

In DVT, as a result of the risk factors above, the clotting system works more than the systems which prevent or melt clots, which causes the clot to form inside the blood vessel.


A blood clot inside a vein.

How does it feel?

Clots form mostly in the veins of the legs or in the pelvis (the hip area). Less commonly, they can form in our arms.

As a result of the clot, the leg gets swollen, and may feel warm and look redder than the other leg. It can also hurt or be tender to touch.

You can see above that this disease is tagged as danger: high. If all it does is pain in the leg, you might ask yourself what’s so dangerous. The danger is that these clots can break loose from their original location, travel through the bloodstream to the lungs, and block the blood flow in the lungs (a condition called pulmonary embolism). This is life threatening


Other than that, DVT can damage the veins in the leg in the long run (a condition called chronic venous insufficiency).

How is it discovered?

There are a few ways to discover DVT:

  1. An ultrasound of the legs – It can detect the blood flow in the legs and show if it’s blocked by the clot.
  2. A blood test – Which can discover if you have DVT (the test is called D-Dimer).
  3. Venography – This is an X-ray picture of the blood flow through your veins.

How is it treated?

There are 2 ways to treat DVT:

  1. Above we mentioned that as well as the system in our body which is responsible for clotting, there are systems responsible for stopping the clotting process and for dissolving the clots.

    There are drugs which help these other systems. These drugs are called blood thinners (or in their medical name, anticoagulants). Examples of such drugs are heparin and warfarin. These drugs are usually given for at least a few months until you are out of risk (and if you have a permanent condition which makes your blood clot, you may have to take it for life).

  2. Inferior vena cava (IVC) filter – There are people who can’t get blood thinners, and there are also people who still get DVTs although they take these drugs. For these people, a type of filter is inserted into our vena cava, which is a vein in which the blood travels from the lower body to the heart. Putting the filter there prevents clots from reaching the heart and the lungs.

What happens after treatment?

Treating this condition on time prevents its complications (pulmonary embolism and venous insufficiency).

The bottom line – How do I avoid it?

There are a few things you can do to prevent DVT:

  1. On long flights – Some doctors recommend that you wear compression stockings (they’re available at medical supply stores) during the flight. On long flights you should walk up and down the aisle hourly (working your leg muscles squeezes the veins and moves the blood in them), drink plenty of water (since dehydration, which is more common when you’re on an airplane, can make your blood thicker and drive clot formation), flex and point your feet occasionally, and avoid alcohol and drinks which contain caffeine (since they contribute to dehydration).

    This also applies to long travels by car, when you sit most of the time.

  2. If you have a family history of blood clotting, inform your doctor – This can potentially prevent conditions which run in families and cause blood clotting from putting you at risk for DVT.
  3. When you undergo a surgery or when bedridden – You will be given medications and other measures to prevent DVT from occurring.

This video sums it up: