What are varicose veins?

One-way valves normally allow blood to travel in the veins from the foot back to the heart without flowing back down in the other direction (‘refluxing’). If the valves stop working properly (become leaky or ‘incompetent’) blood pools in the surface leg veins which then swell up over time and become ‘varicose’.

Healthy Vein Valves & Correct Blood Flow

Damaged Vein Valve & Incorrect Blood Flow

Common places for these incompetent valves are in the groin, causing varicose veins on the inside of the thigh, and the lower leg or behind the knee, causing varicose veins at the back of the calf.

What causes Varicose Veins?

It is a relatively common occurrence for the valves within the veins to give away and become incompetent, particularly at the junctions between the deep and superficial venous systems at the groin or behind the knee. So it is the superficial (saphenous) veins that can give rise to varicose veins.

The effect of gravity is very small on the high-pressure arterial system but does have quite a profound effect on the low pressure venous system. When a limb is dependent, such as when a person is walking or sitting upright, gravity causes an increase in pressure within the veins in the leg in the foot are more visible. When the leg and foot is raised above vertical the veins can be seen to empty and are much less prominent.

The one way valves within veins counteract this process when they are healthy and working properly but when the valves fail congestion of blood below those valves occurs causing the veins to distend over time and become varicose. They distend from side to side but also lengthways so become progressively tortuous and unsightly.

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