The cause of varicose veins is fairly simple. Your arteries carry blood away from the heart to the extremities, but your veins have one-way valves which channel blood back to the heart. If those valves cease to function properly, blood doesn't flow efficiently and can cause the veins to become enlarged and congested with blood.

Heredity is the foremost contributing factor causing varicose and spider veins. Women are more likely than men to suffer from abnormal leg veins, and hormonal factors including puberty, pregnancy, menopause, the use of birth control pills, estrogen, and progesterone also contribute to this condition. Pregnant women often develop varicose veins during the first trimester since pregnancy causes increases in hormone levels and blood volume which in turn cause veins to enlarge. In addition, the enlarged uterus causes increased pressure on the veins. Varicose veins due to pregnancy often improve within 3 months after delivery. However, with successive pregnancies, abnormal veins are more likely to remain. Other predisposing factors include aging, standing occupations, obesity and leg injury.

The smaller visibly enlarged veins are commonly known as spider veins, and the more serious version are called varicose veins. Spider veins are small red, blue or purple veins on the surface of the skin. Spider veins often do not cause pain, but simply appear unattractive. Varicose veins are larger, distended veins that are located deeper below the surface of the skin than the smaller spider veins.

Abnormal leg veins can cause pain in the legs, which can be especially bothersome for those who work on their feet. Symptoms are often aggravated by prolonged standing and include feelings of fatigue, heaviness, aching, burning, throbbing, itching, cramping, and restlessness of the legs. Varicose veins can contribute to uncomfortable Leg swelling can also occur. Severe varicose veins can compromise the nutrition of the skin and lead to eczema, inflammation or even ulceration of the lower leg.

Vein disorders are not always visible; therefore diagnostic techniques are important tools in determining the cause and severity of the problem. In addition to a physical examination, non-invasive ultrasound is often used.