Blood is pumped by your heart and circulates around your body in arteries and veins. Arteries take oxygenated blood away from the heart and the veins return blood back to the heart and lungs for refuelling. In the leg there are 2 sets of veins, the deep (invisible) component and the superficial (under the skin) veins. The deep veins can be thought of as the ‘motorway’ of return of blood to the heart and the superficial veins the ‘slip roads’ which feed blood into the deep veins. Other communications (perforating veins) also exist between the deep and superficial vein systems. Blood flow is maintained by muscle contraction ‘the muscle pump’. Contraction of the muscles forces blood up the leg. When the muscle relaxes small valves close and stop the blood being pulled back towards the foot due to the effect of gravity.

If the veins enlarge or the valves fail to function normally the blood flow becomes abnormal swinging both up and down the leg. The volume and pressure of blood within the vein network increases. This is called ‘reflux’ and is the first change that can lead to the development of symptoms and also the typical changes of superficial venous hypertension. Visible large bulging varicose veins may then develop. Sometimes skin changes can occur with thickening and discolouration of the skin and rarely ulceration.