Varicose veins affecting an 80 year male patient. Varicose veins are veins that have become twisted, distended, and lengthened, due to the presence of defective blood valves. These valves prevent the blood, which should move upwards, from sinking to the feet. Defective valves allow the accumulation of blood, causing this knobbly appearance. Leg veins are most commonly affected. Treatment includes the stripping (surgical removal) of the veins, or sclerotherapy, the injection of the veins with an irritant that eventually blocks them, causing the re-routing of the blood.