Varicose veins. Coloured X-ray of varicose veins in the calf of a fifty-five-year-old male. The veins (red), which carry blood back to the heart, are swollen, irregular and distorted. Varicose veins are most common in the legs, but may also be found in the oesophagus or testis. They occur when valves, which usually prevent the backflow of blood and support the pressure from the blood above, become leaky. The veins then stretch and bulge. Support stockings are usually used to treat the condition, although in some cases surgery is needed to remove the veins. Pregnancy, being overweight, and standing for long periods, all increase the risk of varicose veins.