I am a 23 year old female and getting varicose veins on my left thigh. what could this mean?

Leaking valves: Varicose veins are a very common problem and they are due to leaking valves (called reflux) usually in the saphenous veins. Think of your veins like a tree with the trunk being the saphenous vein and the branches being the varicose veins. A venous reflux ultrasound will make the diagnosis. Common causes of this are hereditary, aging and pregnancies in women. They are treatable with a laser.