Varicose veins are a common condition where the veins, particularly those in the legs, become swollen, twisted, and enlarged. They can be large, ropey, and appear blue or purple in color. This condition occurs when vein valves, which help blood flow up the legs and toward the heart, become weak or damaged. This causes the blood to flow back with gravity and pool in the vein, leading to the appearance of varicose veins.
Visible varicose veins are most often caused by leaking and incompetent valves in the saphenous veins, which are just below the surface of the skin. This allows the blood to leak down into the smaller veins in the lower legs, leading to high vein pressures and enlargement of the veins over time.