Validate the Difficulty Scoring System and Develop a Novel Scoring System for Laparoscopic and Robotic Liver Resections

Inclusion Criteria: * All consecutive patients operated at a single institution during a fixed period * Most recent operation date allowed (up till December 31, 2020, to allow three months follow-up). * All minimally invasive hepatectomy approaches can be included, including lap- assisted (hybrid), hand-assisted, robotic-assisted and pure laparoscopy. * The data of all patients including those that had repeat liver resections, concomitant surgeries (e.g. colectomies, hilar lymph node dissection, enbloc resections) may be included * Patients with no "liver tumors" such as recurrent pyogenic cholangitis/ gallbladder may be included * The site of the "lesion/ pathology" will be considered as the tumor site, size will be considered less than 3 cm unless tumor invades the liver. Exclusion Criteria: * • Patients \< 18 years of age * Patients with liver transplant living donor hepatectomies