Causes
The venous system consists of two types of veins:
- Deep veins
- Superficial veins
In a number of places in the leg, the superficial and deep veins are linked by perforating veins. Normally, the valves of the perforating veins allow blood flow only inwards – from the superficial veins to the deep veins.
If the valves stop working properly, the blood is pushed out into the superficial veins, creates a high pressure and can cause the superficial veins to become varicose veins ».