A varicose vein is a swollen protruding vein in which the blood flows backwards. Usually blood in the veins flows from the feet returning to the heart. (The arteries carry the blood in the opposite direction from the heart to the extremities). Valves in the veins control blood flow. If the valves are damaged (they close by leg muscles contracting), the blood in the veins rises and is wp themes unable to flow downward. A non-functioning valve (a very wide vein) causes the blood to flow in the opposite direction, in other words to the legs, causing the vein to enlarge. This condition is called venous insufficiency.   

It is important to know that varicose veins are not considered a serious medical condition, yet the resulting complications can indeed be serious.  Early detection and treatment is critical.