Minimally-invasive liver resections (MILR) are increasingly conducted world-wide today. Several international consensus meetings were convened to enable the safe dissemination of laparoscopic and robotic liver resections. The Iwate difficulty scoring system (Appendix 1) was formulated in Japan to grade the difficulty of liver resections. This was to allow beginners to adopt a stepwise approach to safely perform MILR according to their experience and competency level. Although this system has been recently validated in a recent Japanese multicenter study, it has not been externally validated in a large cohort of patients. Thus far, it has only been validated in several small single center studies. Furthermore, its utility for robotic liver resections has not been well-studied.
To validate the Iwate difficulty scoring system and Institut Mutualiste Montsouris (IMM) scoring system (Appendix 2) in both laparoscopic and robotic liver resections