Q: I travel extensively for work and also have varicose veins. Am I at risk for blood clots? What symptoms should I watch for?
A: The relationship between travel and blood clots has been studied since the 1950s. The actual risk is difficult to determine but for short trips (<4 hours) there is essentially no risk. For longer trips (>4 hours) there is a slight increased risk for blood clots whether traveling by air, car, bus or train. The primary reason seems to be immobility from prolonged sitting which slows blood flow from the legs. Medical conditions can also increase one’s risk for blood clots. Some of these include: recent major surgery, obesity, a personal history of blood clots or blood clotting disorders, pregnancy, oral contraceptives, hormone therapy, and varicose veins.
Fortunately, even with long trips a blood clot is an uncommon event and probably effects much less than 1% of travelers. For those who travel frequently or who are at higher risk there are preventative measures to help increase blood flow in the legs. Periodic calf muscle contraction, avoiding restrictive clothing around the legs or waist, and use of below-the-knee graduated compression stockings all may help. Choosing an aisle seat makes it easier to get up and move around. Those with many risk factors may want to consult with their physician prior to travel. Although taking aspirin has not been proven to prevent travel related blood clots there are other blood thinning medicines for those at highest risk. Finally, problems with blood clots can show up even weeks after travel is complete. Common symptoms include one sided leg swelling, persistent leg or calf pain, chest pain, and difficulty breathing. If any of these occur seek prompt medical evaluation.