The exact cause of<unk> s is not certain, but a common denominator is generally<unk>  stasis, which may be caused by chronic<unk>  insufficiency, and/or congestive heart failure.<unk>  stasis causes the pressure in veins to increase. The body needs the pressure gradient between arteries and veins in order for the heart to pump blood forward through arteries and into veins. When<unk>  hypertension exists, arteries no longer have significantly higher pressure than veins, and blood is not pumped as effectively into or out of the area.<unk>  hypertension may also stretch veins and allow blood proteins to leak into the extravascular space, isolating extracellular matrix (ECM) molecules and growth factors, preventing them from helping to heal the wound. Leakage of fibrinogen from veins as well as deficiencies in fibrinolysis may also cause fibrin to build up around the vessels, preventing oxygen and nutrients from reaching cells.<unk>  insufficiency may also cause white blood cells (leukocytes) to accumulate in small blood vessels, releasing inflammatory factors and reactive oxygen species (ROS, free radicals) and further contributing to chronic wound formation. Buildup of white blood cells in small blood vessels may also plug the vessels, further contributing to ischemia. This blockage of blood vessels by leukocytes may be responsible for the "no reflow phenomenon," in which ischemic tissue is never fully reperfused. Allowing blood to flow back into the limb, for example by elevating it, is necessary but also contributes to reperfusion injury. Other comorbidities may also be the root cause of<unk> s. It is in the crus that the classic<unk>  stasis ulcer occurs.<unk>  stasis results from damage to the vein valvular system in the lower extremity and in extreme cases allows the pressure in the veins to be higher than the pressure in the arteries. This pressure results in transudation of inflammatory mediators into the subcutaneous tissues of the lower extremity and subsequent breakdown of the tissue including the skin. Wounds of the distal lower extremities arising from causes not directly related to<unk>  insufficiency (e.g., scratch, bite, burn, or surgical incision) may ultimately fail to heal if underlying (often undiagnosed)<unk>  disease is not properly addressed.
Venous ulcer
Arterial insufficiency ulcer
Callous ulcer
Pressure ulcer
Buruli ulcer
Varicose veins
Genital ulcer
Cushing ulcer