Causes of Varicose veins

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Blood returning to the heart flows upwards from the legs. It is moving against gravity so the veins in the legs have to work hard to pump a heavy amount of blood. The flow is helped by a series of one-way valves in the veins that only allow the blood to move upwards (against gravity). This reduces the pressure of blood below by supporting it at different stages on its way up.

If the vein valves are leaky, the weight of the blood going from the heart to the lower legs presses on the walls of the veins. The blood cannot drain properly and so flows back down again causing the veins to bulge and stretch. Veins near the surface of the leg arenâ€™t supported by muscles, so there is nothing to stop them getting bigger with the increased pressure of blood. This pressures causes the surface veins to stretch, bulge and become winding in shape (tortuous). It is only usually the surface veins that are affected because the deep veins are well supported by surrounding tissue.

Varicose veins tend to run in families, and there is probably a genetic tendency to leaky valves. Being overweight increases the risk of varicose veins, as does tight clothing and standing up for long periods of time, for example as part of your job.

Pregnant women can get varicose veins because of the pressure on the veins in the pelvis as the womb (uterus) expands. Women who have had children are more likely to have varicose veins. For women, the veins can also get worse before and during your period because of the increased pressure in your abdomen.

People with conditions that affect the blood flow, such as diabetes, are more prone to varicose veins, as are people with a previous vein disease such as thrombophlebitis.