What Is a Venous Ulcer?
When the vein valves or the calf muscle pump in the leg do not work properly, blood can't flow normally and it pools in the lower leg. The vein walls stretch and the valves no longer close tightly. This increases pressure in the leg veins, causing the legs to swell.
Swollen, congested tissue in the legs don't get enough oxygen and nutrients. Waste products aren't transported back into circulation, so they build up in the tissue. This can cause an open sore, called a venous ulcer, in the skin around your ankle or lower leg.
Even a slight injury to a swollen leg can cause the skin to break down. This condition is known as chronic venous insufficiency or post-phlebitic syndrome.