Varicose veins frequently occur due to malfunctioning vein valves, causing increased pressure and the appearance of large, visible, twisted veins on the leg. This is often a result of valve failure in the saphenous veins, causing blood to flow down the leg into these bulging veins. The ongoing pressure causes the varicose veins to enlarge and extend, sometimes twisting into snake-like shapes and eventually forming a cluster of veins, despite the leg's unchanged length.
It's important to note that many patients have significant venous disease in one or more of their saphenous veins and do not have any visible varicose veins on the skin surface.
