Deep Venous Thrombosis (DVT)

Deep and Superficial Veins

There are two different types of veins inside the leg.  There are superficial veins, which sit just below the skin and are easily seen on the surface.  These often are the ones that developed varicosities or spider veins.  Then there are deep veins which are located deep within the muscles of the legs.  Blood flows between the superficial veins and the deep veins through smaller veins, called perforator veins.  Both superficial and perforator veins have one-way valves that allow the blood to flow in only one direction.

Blood clots can form in either the superficial veins or the deep veins.  When they form in the superficial veins there is very little risk that they will travel and cause problems in other areas of the body.  They form, for the most part, along a track of vein that has become varicose because of the stagnation of the blood.  The same is true for blood clots that form in the deep vein systems.  They form because of the stagnation, the inability of the blood to move quickly, through the venous system.