Blood clots that form inside the veins of the legs, called Deep Venous Thrombosis (DVT), are a common problem following many types of surgical procedures. It is true that these blood clots can also form in certain individuals who have not undergone any recent surgery. These blood clots form in the large veins of the calf and may continue to grow and extend up into the veins of the thigh, and in some cases into the veins of the pelvis.

The risk of developing DVT is much higher following surgery involving the pelvis and the lower extremities. There are many reasons that the risk of DVT is higher after surgery. The body is trying to stop the bleeding associated with surgery and the body's clotting mechanism is very hyperactive during this period. Injury to blood vessels around the surgical site from normal tugging and pulling during surgery, can set off the clotting process. Finally, blood that doesn't move well sits in the veins and becomes stagnant. Blood that sits too long in one spot usually begins to clot.

Why do we worry about blood clots? Blood clots that fill the deep veins of the legs stop the normal flow of venous blood from the legs back to the heart. This causes swelling and pain in the affected leg. If the blood clot inside the vein does not dissolve, the swelling may become chronic and can cause permanent discomfort and swelling. While this may seem bad enough, the real danger that a blood clot poses is much more serious. If a portion of the forming blood clot breaks free inside the veins of the leg, it may travel through the veins to the lung where it can lodge itself in the tiny vessels of the lung. This cuts off the blood supply to the portion of the lung that is blocked. The portion of the lung that is blocked cannot survive and may collapse, which is called a pulmonary embolism. If a pulmonary embolism is large enough and the portion of the lung that collapses is large enough it may cause death. With this in mind, it is easy to see why prevention of DVT is a serious matter. Reducing the risk of developing DVT is a high priority following any type of surgery. Things that can be done to reduce the risk of developing DVT fall into two categories:

• Mechanical - getting the blood moving better.
• Medical - using drugs to slow the clotting process.

Blood that is moving is less likely to clot. Getting YOU moving so that your blood is circulating is perhaps the most effective treatment against developing DVT. While you are in bed, there are other things that can be done to increase the circulation of blood from the legs back to the heart. Simply pumping your feet up and down (like pushing on the gas pedal) contracts the muscles of the calf, squeezes the veins in the calf, and pushes the blood back to the heart. You can't do this too much!

Pulsatile stockings do the same thing. These special stockings that wrap around the calf and thigh are inflated by a pump every few minutes, squeezing the veins in the calf and thigh pushing the blood back to the heart. Support hose are still commonly used following surgery. These hose work by squeezing the veins of the leg shut. This reduces the amount of stagnant blood that is pooling in the veins of the leg and reduces the risk of that blood clotting in the veins. Finally, getting you out of bed and walking will result in muscle contraction of the legs and keep the blood in the veins of the leg moving.

Medical

Drugs which slow down the body's clotting mechanism are widely used following surgery of the hip and knee to reduce the risk of DVT. These drugs include aspirin in very low risk situations and heparin shots twice a day in moderately risky situations. For conditions that have a high risk for developing DVT, several very potent drugs are available that can slow the clotting mechanism very effectively. Heparin can be given by intravenous injection, while a new drug called Lovenox� can be given in shots administered twice a day. Coumadin� can be given by mouth and is the drug of choice when the clotting mechanism must be slowed for more than a few days.

In most cases of hip and knee surgery, both mechanical and medical measures are used at the same time. It has become the norm to use pulsatile stockings immediately after surgery, have you begin exercises immediately after surgery, get you out of bed as soon as possible and place you on medication to slow the blood-clotting mechanism.