Deep Vein Thrombosis, or DVT, occurs when a blood clot forms in one or more of the deep veins in your body, typically your legs. DVT can cause leg pain or swelling, but may occur without any symptoms. Symptoms of DVT may include: pain and tenderness in one leg, swelling in one leg, visible veins, pain or cramping in the calf, and warmth in the leg.
Long distance air travel increases you risk for leg swelling and discomfort. Here are some tips for flying: maintain a healthy weight, get up and move around every hour, keep your legs uncrossed while sitting, wear compression socks or stockings, point and flex your feet throughout your trip, drink plenty of water and avoid excessive alcohol during flights.
Some of the most common risk factors for venous disorders: heredity, age over 40, pregnancy, obesity, prolonged sitting or standing, long distance travel, surgery or trauma, and infectious disease.