If the varicose veins are larger, ultrasound-guided foam sclerotherapy is a good treatment. The liquid that is injected into the veins is foamed in advance. The thicker foam works better on the vessel wall. By making an ultrasound during the treatment, the phlebologist or vascular surgeon checks whether the foam is exactly in the right place. Also with this treatment follows the flattening with a stocking. The stocking remains on for 2 to 7 days, depending on the size of the injected veins.