Telangiectasias, also known as spider veins, are small dilated blood vessels near the surface of the skin or mucous membranes, measuring between 0.5 and 1 millimeter in diameter.
These dilated blood vessels can develop anywhere on the body but are commonly seen on the face around the nose, cheeks, and chin. Dilated blood vessels can also develop on the legs, although when they occur on the legs, they often have underlying venous reflux or "hidden varicose veins" (see "Venous reflux" below). When found on the legs, they are found specifically on the upper thigh, below the knee joint, and around the ankles.
Many patients who suffer with spider veins seek the assistance of physicians who specialize in vein care or peripheral vascular disease. These physicians are called vascular surgeons or phlebologists. More recently, interventional radiologists have started treating venous problems.
In the past, people used to think that leg varicose veins or telangectasia were caused by high venous pressure or "venous hypertension". However it is now understood that venous reflux disease is usually the cause of these problems (see above for reference for "venous reflux".[full citation needed]
Telangiectasia in the legs is often related to the presence of venous reflux within underlying varicose veins. Flow abnormalities within the medium-sized veins of the leg (
reticular veins) can also lead to the development of telangiectasia.
Factors that predispose to the development of varicose and telangiectatic leg veins include
Age: The development of spider veins may occur at any age but usually occurs between 18 and 35 years, and peaks between 50 and 60 years.
Gender: It used to be thought that females were affected far more than males. However research has shown 79% of adult males and 88% of adult females have leg telangectasia (spider veins).
Pregnancy: Pregnancy is a key factor contributing to the formation of varicose and spider veins. The most important factor is circulating hormones that weaken vein walls. There's also a significant increase in the blood volume during pregnancy, which tends to distend veins, causing valve dysfunction which leads to blood pooling in the veins. Moreover, later in pregnancy, the enlarged uterus can compress veins, causing higher vein pressure leading to dilated veins. Varicose veins that form during pregnancy may spontaneously improve or even disappear a few months after delivery.
Lifestyle/occupation: Those who are involved with prolonged sitting or standing in their daily activities have an increased risk of developing varicose veins. The weight of the blood continuously pressing against the closed valves causes them to fail, leading to
vein distention.