From my personal experience blood clots can be common in people who are less active such as people who are bed ridden and it has come into popular knowledge that some inactive people who sit on airplanes during long flights are in danger of getting blood clots. It can be helpful to wear compression stockings during situations of extended inactivity to help avoid clotting in the lower extrmities. Simply pumping your feet as you sit can be beneficial in aiding the blood flow while you sit. When I was in the hospital they gave me the drug Heparin to dissolve the clots and then Coumadin/Warfarin as a maintenance drug. I am currently on 20 mgs/day and get protime blood clotting tests monthly.