What is a complex liver resection?

Liver resection remains the only curative treatment for primary and metastatic liver tumors. Defining preoperatively the complexity of liver resection might help to plan surgical strategy, to estimate the risk of perioperative events and postoperative complications. To date three classifications have been described to estimate the complexity of liver resection (the Gayet-Kawaguchi, the Strasberg-Lee- and the Nagorney-Shubert classifications) based on the extent of liver resection, the type of liver resection, the diagnosis, and the presence of associated procedures. An increased complexity is associated with higher blood loss, postoperative morbidity, and mortality. Based on the analysis of the literature we propose that complexity for a liver resection could be defined based on the association of different factors: type of hepatectomy, size and location of the tumors, need for vascular resection, patients morphology and comorbidities and quality of underlying liver parenchyma. As complexity of liver resection increases, there is a need of dedicated surgical techniques to reduce bleeding and liver ischemia that correlate with the development of postoperative lethal liver failure. High complex hepatectomies could benefit from technical strategies derived from liver transplantation including total vascular exclusion with or without in-situ hypothermic perfusions under veno-venous bypass, ante-situm approach and ex-situ liver resection with autotransplantation.