When we walk the veins in the leg are squeezed by the calf and thigh muscles. This Muscle Pump pumps the blood in the legs up towards the heart. Valves in the veins normally stop the blood falling back down towards the feet when the muscle isn’t active. If we stand still, blood normally pools within the veins until it can be pumped back to the heart when we start to walk again. Over time, particularly if there is a family history, or if we spend a lot of time standing still, the filled veins with pooled blood can stretch the supporting structures of the valves in the veins and this makes them leaky. The result is that when we start to walk with leaky vein valves, and the muscle pump pumps, the blood in the veins goes up and down rather than just towards the heart. The veins beneath the skin become larger as they cope with the increased, up and down, blood flow. Soon they become visable and wiggly Varicose Veins. Very small networks or webs of red, purple or blue veins often occur alongside large varicose veins; so called Thread Veins (also known as Spider Veins or Flare Veins).
Life-style factors play a part developing Varicose Veins and Thread Veins. Prolonged standing, it is believed, causes varicose veins. Diet may also be a factor, they are seen more frequently in people with increased BMI (Body Mass Index – a measure of obesity).
Hormonal changes at key times in life such as puberty, pregnancy and the menopause is also thought to be connected to the development of varicose and thread veins. Varicose veins are frequently noticed during pregnancy. The combination of increased fluid and blood, hormonal changes and the increasing pressure on veins inside the abdomen as the uterus and baby increase in size means that veins can become more prominent. You should not have varicose veins treated surgically during pregnancy. The good new is that, in most cases, pregnancy induced varicose veins improve or disappear within weeks of the birth of the baby.