What causes blood clots in the leg?

Long list of causes. There are a lot of possible causes and risk factors of blood clots in the legs. Here are some: - long periods of sitting - prolonged bed rest - inherited clotting diseases - any kind of injury or trauma - cancer - smoking - obesity or overweight - family history of blood clots - blood draws or catheters in veins, including pacemakers - birth control pills - congestive heart failure - ibd.