Dear Dr. Berger,
I live abroad, so I have to take a lot of trans-Atlantic flights. During long plane trips my feet and ankles get swollen. I’m worried this is a sign that I’ll get a blood clot during a flight. I have tried several strategies: I stand up during the flight and I sit in different positions. But I’m not sure it’s helping (or not helping enough). In case it’s relevant, I will mention that my joints are particularly sensitive and they are aching this week. I get a number of cramps in different parts of my body when I sit in one place for a long time. What can I do so that flying doesn’t harm my body as much? Should I be worried about a possible DVT?
"I'd rather be a bird"
First of all, a brief introduction for some readers who might not know. Your question has to do with DVTs (deep venous thromboses), blood clots in the deep leg veins, and how they can be prevented. As you know, such blood clots can cause swollen, aching calves. Even more important: in occasional, rare cases, the clots can break off the blood vessel and “fly away” to other parts of the body, potentially harming the lungs or the brain (these are “emboli,” migratory clots). Some people need to be more on their guard against swollen legs in general, whether in the air or on the ground, because of blood vessel related diseease (e.g., those with diabetes or arterial disease).
People who are generally healthy should know that DVTs due to air travel are not so common and are rarely associated with symptoms. An academic review of relevant studies in 2007 showed that pulmonary emboli (that is, clots that travel to the lungs) occur 27 times out of every 1 million flights (it’s about as likely to get hit by lightning). One half of one percent (1 in 200) of all flights are associated with symptomatic DVTs.
But how often do DVTs happen and what increases their risk? In another study conducted in the UK in 2008, it was estimated that 50 of a total of 2,800 airplane passengers had leg clots, but no one had symptoms. All clots (both symptomatic and those not associated with symptoms) are more likely to happen during longer flights and in people with vein and artery problems.
There is a simple way to prevent them: a pair of compression stockings are effective in decreasing the risk of blood cots in the legs. They are available in fashionable colors like black, beige, and brown (a niche, perhaps, for a capable fashion designer).
Bon voyage and don’t worry: leg clots happen rarely on airplane flights, are generally not associated with symptoms and are easily preventable with compression stockings.