As Dr. Rand pointed out, we encounter 2 varieties of venous blood clots; 1. SUPERFICIAL thrombophlebitis and 2. DEEP Venous Thrombosis (DVT). The propensity to clot depends on your family history (there are genetically inherited clotting diseases), length of immobility and factors such as estrogen / birth control intake, obesity, underlying serious disease , smoking , etc. The first group is clotting seen in superficial veins (even in an IV site) that resolve rapidly with local heat, anti-inflammatory agents and, if needed, antibiotics. The second group is seen in the deep veins of the legs and pelvis. It can be greatly decreased by the use of leg pumps during surgery and a lot of mobility after surgery, during recovery. Once the DVT clots are formed, we try to get them to stop from increasing in size or to become detached from the vein walls and flow to the lungs. Eventually, the clots scar to the vein walls and no longer threaten a shower of clots. If you did not demonstrate a clot in the first 2-3 weeks after surgery, it is VERY unlikely that you will have one. The key is hydration and ambulation - drink and walk.