Varicose veins are blood vessels that become swollen, blue, and twisted from the pooling of excess blood. This happens when blood, instead of returning upwards to the heart, is allowed to flow back down due to a weakness in the valves or in the vein walls. In either case, the valves which normally prevent the downward flow of blood no longer fit tightly inside the vein, and leakage occurs. The legs are the most common site for varicose veins. While the condition is often hereditary, it can be encouraged by anything that impedes circulation such as tight elastic on the legs, lack of exercise, sitting or standing for prolonged periods, and hormonal changes from pregnancy or birth control pills. Some patients may have no symptoms other than the bluish, raised, and twisted appearance of the veins. Others may experience a feeling of fatigue or heaviness in the legs before the veins are even visible. Swollen feet and ankles, nighttime leg cramps, a dull ache, and soreness or itching near the veins are other possible signs. Symptoms are typically worst at the end of the day. In severe cases, varicose veins can result in dry or discolored skin and open sores known as ulcers.