It is estimated that up to 25 percent of women and 15 percent of men suffer from varicose or spider veins, caused by valvular insufficiency. Throughout your body, arteries carry blood from your heart to the tissues, and veins return blood from the tissues back to the heart. In the legs, your veins carry blood uphill, against gravity. In order to do this efficiently, our veins have numerous one-way valves along their course that function to prevent the blood from flowing backwards. If one or more of these valves fail to close properly, blood can leak through them and pool within the vein segment beneath the valve. Valvular insufficiency can over fill the vein, resulting in stretching or bulging of the vein and vein branches.
Spider veins are generally thin red, blue or purple veins immediately below the skin surface that are either flat or only minimally bulging. Varicose veins tend to be larger and to bulge more prominently.
Genetics, pregnancy, aging, obesity, prolonged standing or sitting, leg trauma, prior leg vein clots or history of deep vein thrombosis (DVT) can increase your risks for vein-related leg problems.
– Karen J. Ho, MD, vascular surgeon, Northwestern Medical Group