Varicose veins

Varicose veins are the largest ropy veins seen especially on the legs. They often look like cords and appear twisted and bulging. Varicose veins, which are are deeper and larger than spider veins, typically 3 mm or more in diameter, develop slowly, but once they start they progress. Human veins have a series of valves to keep blood flowing back towards the heart. If the valves fail, the blood flows in reverse – into the superficial veins and down the leg. As a result, the veins enlarge and become varicose.
Varicose veins hold more blood at higher pressure than normal, forcing fluid into surrounding tissue. As a result, the leg swells and feels heavy.
Varicose veins are one of the most common problems of blood vessels. Approximately 40 million people in the United States have varicose veins. Varicose veins are common in older adults (Most people with varicose veins are between ages 30 and 60), especially women (the condition occurs four times more often in women than in men). It is estimated that in USA about 19% of men and 36% of women have varicose veins.

Normal veins have one-way valves that allow blood to flow upward only to return to the heart and lungs. A varicose vein has valves that are not functioning properly. The blood can flow upwards, but tends to pool in the vein because of valve dysfunction.

Here you can find more information about varicose vein treatment