How can i tell if i have a blood clot in my leg after a plane trip?

Swollen leg: Usually swelling in one leg is first clue, though not definitive. If you are concerned or have problems with excess clotting, discuss with your doctor before travel. May suggest compression stockings or even blood thinners. For most people, staying hydrated and moving around/leg exercises are sufficient.

Ultrasound: If you are having pain or swelling in your leg, you should contact your primary physician to have an ultrasound, or duplex of the veins in your legs. If there is a dvt, it would then be treated with blood thinners.

Ultrasound exam: The only way to be sure that one does not have a blood clot in a limb is to have a venous duplex ultrasound exam, which will fully evaluate the superficial and deep venous systems of your legs. Flying at high altitude, particularly for extended flights, does put one at higher risk of developing a deep venous thrombosis. If you are concerned, you should be evaluated, and asap to avoid complications.