(See also Overview of the Venous System.)
The precise cause of varicose veins is unknown, but the main problem is probably a weakness in the walls of superficial veins (located just under the skin). This weakness may be inherited. Over time, the weakness causes the veins to lose their elasticity. Veins stretch and become longer and wider. To fit in the same space that they occupied before they stretched, the elongated veins become convoluted. They may appear as a snakelike bulge beneath the skin.
Women may be more likely to develop varicose veins than men, and their initial occurrence may be during pregnancy. In addition, the following can contribute to the development of varicose veins in predisposed people:
More important than the elongation is the widening of the veins, which causes the valve flaps (cusps) to separate. When the person stands, the blood is pulled backward by gravity and is not stopped because the valve cusps are separated. Thus, blood flows backward, rapidly filling the veins and causing the thin-walled, convoluted veins to enlarge even more. Some of the connecting veins, which normally allow blood to flow only from the superficial veins into the deep veins, also enlarge. If they enlarge, their valve cusps also separate. Consequently, blood squirts backward into the superficial veins when the muscles squeeze the deep veins, causing the superficial veins to stretch further.
Many people with varicose veins also have spider veins, which are enlarged capillaries.
Besides being unsightly, varicose veins commonly ache and cause a sensation of tiredness in the legs. However, many people, even some with very large veins, have no pain.
The lower part of the leg and ankle may itch, especially if the leg is warm after a person has been wearing socks or stockings. Itching can lead to scratching and can cause redness or a rash, which is often incorrectly attributed to dry skin. The pain is sometimes worse when varicose veins are developing than when they are fully stretched.
Only a small percentage of people with varicose veins have complications, such as dermatitis, superficial venous thrombosis, and inflammation of the veins (phlebitis), or bleeding. People with varicose veins can also develop chronic venous insufficiency.
Phlebitis may occur spontaneously or result from an injury. Although usually painful, phlebitis that occurs with varicose veins is rarely harmful.
Dermatitis causes a red, scaling, itchy rash or a brown area, usually on the inside of the leg above the ankle. Scratching or a minor injury, particularly resulting from shaving, can cause bleeding or development of a painful ulcer that does not heal. Ulcers may also bleed.
Varicose veins can usually be seen bulging under the skin, particularly when people are standing.
Ultrasonography can identify varicose veins but is not usually done unless doctors think there may also be malfunction of the deep veins (see Chronic Venous Insufficiency and Postphlebitic Syndrome). Malfunction of the deep veins is suggested by changes in the skin or by swollen ankles. The ankles swell because fluid accumulates in the tissue under the skin—a condition called edema. Varicose veins alone do not cause edema.
Although individual varicose veins can be removed or eliminated by injection therapy or surgery, the disorder cannot be cured. Thus, treatment mainly relieves symptoms, improves appearance, and prevents complications. Elevating the legs—by lying down or using a footstool when sitting—relieves the symptoms of varicose veins but does not prevent new varicose veins from forming. Usually, varicose veins that appear during pregnancy largely subside during the 2 or 3 weeks after delivery. During this time, they should not be treated.
Elastic stockings (support hose) compress the veins and prevent them from stretching and hurting. People who do not want surgery or injection therapy or who have a medical condition that prevents them from having these treatments may choose to wear elastic stockings.
Injection therapy seals the veins so that blood can no longer flow through them. A solution, such as sodium tetradecyl sulfate, is injected into the vein to irritate it and produce a blood clot (thrombus). In essence, this procedure produces a harmless kind of superficial venous thrombosis. Healing of the blood clot leads to formation of scar tissue, which blocks the vein. However, the blood clot may dissolve instead of becoming scar tissue, and the varicose vein then reopens. Also, new varicose veins often develop.
Current sclerotherapy techniques also use special bandaging that reduces the size of the blood clot by compressing the diameter of the injected vein. A smaller blood clot is more likely to form scar tissue, as desired. A further advantage of this technique is that adequate compression virtually eliminates the pain that usually accompanies the vein irritation caused by the technique.
Although injection therapy is more time-consuming than surgery, it has several advantages:
Surgery is no longer used as a routine treatment for varicose veins. When surgery is done, it aims to remove as many of the varicose veins as possible. However, surgeons try to preserve the saphenous vein. This vein is the longest superficial vein in the body, extending from the ankle to the groin, where it joins the femoral vein (the main deep vein in the leg). Surgeons try to preserve the saphenous vein because it can be used for bypass procedures in case blockage ever develops in the heart vessels or other major body vessels. If the saphenous vein must be removed, a procedure called stripping is done. The surgeon makes two incisions, one at the groin and one at the ankle, and opens the vein at each end. A flexible wire is threaded through the entire vein and then pulled out to remove the vein.
To remove other varicose veins, the surgeon makes incisions in other areas. Because the superficial veins play a less significant role than the deep veins in returning blood to the heart, their removal does not impair circulation if the deep veins are functioning normally.
Removal of varicose veins is a lengthy procedure, so the person is usually given a general anesthetic. This procedure relieves the symptoms and prevents complications, but it leaves scars. The more extensive the procedure, the longer the time before new varicose veins develop. However, removal of varicose veins does not eliminate the tendency to develop new varicose veins.