Varicose veins are not a blockage of blood vessels in the common sense of the word, or a blockage of something inside the blood vessels that prevents blood from going up. Varicose veins and blocked blood vessels are two different diseases. Varicose veins are caused by the fact that there are many valves inside the veins of the body that ensure that the blood travels from the bottom to the top and does not flow backwards. Varicose veins can occur when these valves do not close properly, leading to backflow of blood. So, it is not necessarily that something is blocked inside the veins, but the most crucial thing is the reflux of blood, which causes the symptoms of poor blood return.