Varicose veins are abnormal, dilated blood vessels caused by a weakening in the vessel wall. They might appear as clusters of blue or purple veins and are sometimes surrounded by thin red capillaries known as spider veins. 0:00 What are Varicose Veins? 0:55 Symptoms & Risk Factors 2:02 Diagnosis & Treatment 4:04 When to Call a Doctor 4:50 After Treatment