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Travel and DVT

I got to thinking about writing this blog during my recent trip to SE Asia. It took 3 flights, and 24 hours of flying time, exclusive of time at the airport to get there. All in all, I think flying from the East Coast of the US to SE Asia can be draining, but more importantly it can potentially cause clotting in your lower legs due to immobility.

Long distance travel, regardless if by car, train, boat or plane increases the risk of developing a clot in the veins in your leg. This is commonly referred to as deep venous thrombosis (DVT). Immobility for more than four hours may contribute to developing a DVT.

This is especially true of long journeys with limited options to move around.

The risk of DVT doubles after four hours of sedentary travel, but the absolute risk is still pretty low, about 1 in 6,000. That’s because a DVT occurs when there is a perfect storm of other risk factors.

The estimated risk of DVT caused by prolonged travel is variable and those at highest risk are those who spend longer periods of time traveling.

Although the duration of increased risk of DVT formation is unknown, the incidence appears to be highest in the first two weeks after travel and returning to normal by about eight weeks. The reason for the time lag is the clot in the leg veins may have already been there during travel and it just grew to cause symptoms afterwards.

The majority of those who develop travel related DVT have one or more known risk factors for clot formation.

What are common DVT risk factors?

Virchow’s Triad (Named after a German Physician) describes the three physiological factors thought to contribute to clot formation in blood vessels.

The triad consists of stasis, injury and hyper-coagulability. The most common risk factors are DVT when traveling are:

Recent Surgery

Prior history of DVT



Advanced age

Birth control pills


Female Gender

What are the symptoms of a DVT?

Swelling of your calf, change in leg color (a red or blue tinge), warm or itchy leg. As the clot gets bigger, the swelling can become painful or you may feel like you have a muscle cramp or charley horse.

A potentially deadly complication of the DVT is a pulmonary embolism. If you have these above symptoms and suddenly have trouble breathing, the DVT may have traveled to your lung and caused a pulmonary embolism. This require immediate medical attention. See below.

What can happen if you develop a DVT?

A DVT can be life-threatening if the clot breaks off, travels to the lungs and gets stuck in a major blood vessel in your chest. This can limit blood flow to one or both lungs which can strain the heart to the point that it stops. This is a referred to a pulmonary embolism (PE) and is very serious.

What can reduce the risk of a DVT?

Mobility, mobility, mobility!

During any trip, regardless of mode of transportation you have to move! If stuck in a window seat and you can’t get up as frequently as you would like, move your ankles in circles.

Flex and extend the calf muscles and stretch often. If possible get up and move about every hour. This encourages blood flow and reduces blood stasis. Wear loose clothing so that blood flow is not constricted.

Keep in mind that although there is no definitive evidence that dehydration or alcohol consumption contribute to an increased risk of DVT, dehydration can theoretically promote forming blood clots and alcohol consumption can promote immobility which can promote clot formation.

So drink plenty of water and stay away from alcohol. Below knee graduated compression stockings that provide 15 to 30 mmHg of pressure may decrease the incidence of DVT associated with prolonged immobility due to travel.

Take away points

You need to be aware that long distance travel can increase the risk of forming a DVT, although the overall incidence is small.

The rates are highest in those who spend longer periods of time traveling. The peak rate occurs within the first two weeks after travel.

Most individuals who develop a DVT from traveling have at least one risk factor. If traveling long distance, regardless of mode of travel or risk factors it’s not a bad to take some basic preventive measures.

Frequent ambulation, calf exercises, avoidance of dehydration or alcohol and wearing graduated compression stockings can help reduce the risk of a DVT.

Safe travels.

Please remember that medical information provided by us must be considered an educational service only. This blog should not be relied upon as medical judgement and does not replace your physician’s independent judgement. This is NOT medical advice. Please seek the advice of your physician.

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