The patient will be admitted for surgery and anaethetised in the usual way. Once the vein and artery have been dissected and prepared for anastomosis a sealed envelop will be opened. This will instruct the surgeon to perform the anastomosis with either a conventional continuous prolene suture or interrupted U Clips. The envelop will also contain a study number which is recorded on the operation note. The operation not must no include the words prolene anastomoiss or clipped anastomosis. In this way subsequent assessment by nephrologists will be blinded.