text: <unk><unk>  are more common in women than in men, and are linked with heredity. Other related factors are pregnancy, obesity, menopause, aging, prolonged standing, leg injury and abdominal straining.<unk><unk>  are bulging<unk>  that are larger than spider<unk> , typically 3 mm or more in diameter.<unk><unk>  are distinguished from reticular<unk>  (blue<unk>  and telangiectasias (spider<unk>  which also involve valvular insufficiency, by the size and location of the<unk> .
  The causes of<unk><unk>  are not clearly understood. In some cases, it is caused by weak or damaged valves that are usually present in<unk> . These valves help ensure that blood in<unk>  down not flow in the backward direction. However, when these valves are weak or damaged, blood tends to flow backward. This increases the pressure inside the<unk> , causing them to become ballooned and tortuous over time. In some other cases, walls of<unk>  are already weak and they might form outpouchings from the pooling and pressure of blood .
option_0: Varicose veins causes
option_1: Deep vein thrombosis causes
option_2: Varicose veins risk factors
option_3: Diabetic foot causes
option_4: Deep vein thrombosis triggers
option_5: Buerger's disease causes
option_6: Cholesterol emboli syndrome causes
option_7: Varicose veins other diagnostic studies