Slowed blood flow. If you have surgery or are
inactive for a period of time (for example, if you are bedridden or must sit
while on a long flight or car trip), blood flow in your legs is slowed, which
allows a blood clot to form.
Damage to the blood vessels. Surgery or injury may
damage your blood vessels.
Changes in the blood itself.Cancer or certain
inherited factors may cause your blood to clot more
quickly than normal.