Saphenous veins are the underlying cause of severe varicose veins in about 90% of patients.
Your leg has two saphenous veins.
The great saphenous vein which runs inside the leg from the ankle to the groin.
The small saphenous vein which runs up the back of the calf and terminates behind the knee.
You can’t see saphenous veins because they lie deep under the skin. Saphenous veins are NOT “deep veins” because they are not inside the muscles of the leg.
The blood in the saphenous veins normally flows up the leg draining into either the deep vein in the groin or into the deep vein behind the knee.
Inside the saphenous veins are a series of non-return valves which prevent blood from slipping back down the leg from the force of gravity.
If the saphenous vein walls become weak and lose their elasticity the vein starts to dilate. (see images below). When this happens the valves won’t close properly and blood starts leaking down the leg.
This reverse direction of flow causes back pressure on the surface veins lower down the leg and after a while the surface veins start to dilate and become “varicose veins”.
Varicose veins don’t work properly because the blood flow is in the wrong direction - instead of the blood flowing back to the heart it is flowing back into the skin. Over time if the varicose veins become severe and are not treated then skin damage on the lower leg will occur and his can eventually lead to “venous ulcers”.