Minor hepatectomies: focusing a blurred picture. Analysis of the outcome of 4471 open resections in non-cirrhotic patients

Background: Liver surgery is moving toward a parenchyma-sparing approach, favoring minor hepatectomies (MiH) instead of major resections. MiH encompasse a wide range of procedures at different complexity, whose outcomes have not been fully elucidated. Methods: Consecutive patients undergoing a first liver resection in 17 highly-experienced centers were considered. Cirrhosis, associated digestive/biliary resection and mini-invasive surgery were exclusion criteria. We distinguished limited resections (LR), (mono)segmentectomies (S), left lateral sectionectomies (LLS), right anterior sectionectomies (RAS), right posterior sectionectomies (RPS), and other bisegmentectomies (BS). In addition: LR with exposure of intrahepatic vessels were defined 'complex LR' (CLR); mono/bisegmentectomies Sg7/Sg8 were defined 'postero-superior segmentectomies' (PSS); segmentectomies Sg1 and combined resections of Sg4s+Sg8+Sg1 were defined 'complex core hepatectomies' (CCH). Outcome of LLS and right hepatectomies (RH) were used as reference standards. Outcome of MiH were adjusted for covariates (liver function, diagnosis, chemotherapy, and center). Results: 4471 MiH were analyzed. In comparison with RH, MiH had lower 90-day mortality (0.5%/2.2%, p<0.001), severe morbidity (8.6%/14.4%, p<0.001), and liver failure rates (2.4%/11.6%, p<0.001), but similar bile leak rate. Non-complex LR had outcome similar to LLS. CLR and S/BS of anterolateral segments (Sg2-6) had higher bile leak rates than LLS (odds ratio (OR)=2.2 and OR=2.7), but similar severe morbidity rates. CCH had the highest bile leak rate (OR=5.5), even higher than RH (OR=1.9), and had severe morbidity rate approaching RH (vs. LLS OR=2.4). PSS and RAS had severe morbidity rates similar to RH (OR=1), while RPS had slightly lower rates. The three procedures had bile leak rates similar to RH. MiH had low liver failure rates (<5%) except for RAS (9.7% vs. 11.6% after RH). Conclusion: MiH include resections having heterogeneous outcome. Mortality rate is low, but MiH can be stratified according to severe morbidity, liver failure and bile leak rates, most complex resections having outcome similar to RH. Bile leak and severe morbidity rates of different MiH in comparison with LLS and RH