Spider veins, also known medically as telangiectasia or venulectasias, are the mildest manifestation of venous insufficiency, similar to varicose veins but smaller. They are small, often tangled groups of tiny blood vessels just under the skin surface that frequently resemble spider webs or tree branches. They are generally red, blue or purple and are clearly visible, usually on the thighs, lower legs and face. Spider veins can sometimes cover large areas of skin, but they are a cosmetic problem only, rarely causing physical symptoms. At least a third of all women and a smaller percentage of men are believed to display the condition.
Spider veins are capillaries, thin vessels directly connected with the larger venous system, and like varicose veins they are caused by venous reflux. Spider veins may be isolated or associated with "feeder" veins or with larger underlying varicose veins, but they are not varicose veins – they do not bulge above the skin surface and do not require medical treatment.
Spider veins can be diagnosed merely by sight. They tend to take on one of three characteristic patterns – a "sunburst" or spider-web pattern radiating outward from a central point, a "tree-branch" pattern, or a "matting" or linear pattern that may be nothing more than a set of thin lines. Even in the absence of physical discomfort, some physicians observing spider veins prefer to conduct ultrasound exams to determine the extent of the problem and the underlying causes of the condition.
Risk factors for spider veins are similar to those for varicose veins – age, heredity, pregnancy, hormonal changes, obesity and extended periods of standing – as well as sun exposure, particularly in fair-skinned people, and injuries to the skin surface. Some physicians believe that exercise, weight loss and the wearing of support hose and flat shoes instead of high heels can reduce the incidence of spider veins.