Varicose veins are distended branches of the major veins in the leg. They become distended due to failure of the valves in the main veins which allows blood to fall back down the leg (reflux). Venous reflux is the major cause of most venous diseases and is almost always the cause of varicose veins. Varicose veins develop in the superficial veins of the leg and mainly affect the great saphenous vein (medial thigh and calf), although they may also affect the small saphenous vein (posterior calf).
Symptomatic varicose veins may lead to more serious conditions:
Brown staining of the skin