Up to 2ml of foam will be injected into each cannula under ultrasound control to observe venous spasm, followed by gentle massaging of the skin to propagate the foam through the segment of vein treated. The surgeon will also endeavour to prevent propagation of fresh foam beyond perforators and junctions into the deep venous system. The patient will be asked to dorsi-flex and plantar-flex their ankle several times to clear any foam which might have entered the deep venous system. At least 30 seconds will be left between each injection of foam. As per the European consensus guidelines a maximum of 12mls of foam will be used at one sitting32 33. Typical volumes of foam reported by Bradbury are 4-12ml in the GSV and 2-8 ml in the SSV34. After ensuring that the axial vein is treated the surgeon can then progress to the treating the tributaries and application of the dressings, as detailed below.