A. Pain and other disadvantages of AV fistula cannulation can be limited by using the so-called buttonhole technique. It was described for the first time as the "contant site method" by Twardowski et al. The authors report on a patient in whom the fistula was too short to use the rope ladder technique. As an alternative, the access was cannulated at a "constant site". Later, in 1984, Krönung used the name "buttonhole puncture technique". It was used primarily in patients treated with home hemodialysis, where cannulation was performed by one single person (often by the patient himself). In order to form a perfect buttonhole it is indeed essential that the fistula is cannulated at exactly the same site and using exactly the same angle every single time. The buttonhole technique has been adopted by the recent "National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF K/DOQI) Guidelines" for vascular access. Studies show that patient pain scores and bleeding time after dialysis are positively influenced when using this cannulation technique.