PCN puncture on fURS (Matryoshika effect?)

This video clip of PCN puncture was performed by Dr Juhyun Park, my junior faculty in my hospital (SMG-SNU Boramae Medical Center). I don't know who named this technique 'Matryoshika', but many surgeons like us are doing this technique when it is really needed.

When the renal stone is impacted in the calyx, PCN puncture can be a difficult procedure. In this situation, we can use the flexible ureteroscopy to facilitate the percutaenous pucture.