Venous insufficiency is the reason venous ulcers form, and the definition is short.
The veins have one-way valves that keep blood flowing up toward your heart. When these valves become weak or the veins become scarred and blocked, blood can flow backward and pool in your legs. This is called venous insufficiency.
What happens next is why the term matters. Blood pooling leads to high pressure in the lower leg veins. The increase in pressure and buildup of fluid makes it more difficult for nutrients and oxygen to get to tissues. The lack of nutrients causes cells to die, damaging the tissue, and a wound can form.
So venous insufficiency is not a wound. It is the condition underneath, and a venous ulcer is one thing that can eventually come of it. There are signs that appear before any sore does. Fluid and blood cells leak out into the skin and other tissues, which can cause itchy, thin skin and lead to skin changes, for example faint, light red discoloration, called stasis dermatitis. This is an early sign of venous insufficiency.
Other early signs are leg swelling, heaviness, and cramping; dark red, purple, brown, hardened skin, which is a sign that blood is pooling; and itching and tingling.
Risk factors for venous ulcers include varicose veins, a history of blood clots in the legs, blockage of the lymph vessels, older age, being female, or being tall, a family history of venous insufficiency, obesity, pregnancy, smoking, sitting or standing for long periods of time usually for work, and a fracture of a long bone in the leg or other serious injuries such as burns, muscle damage, or a large surgery.