A multicenter validation study for determining the condition of nonanatomical or minor anatomical hepatectomies satisfying technical difficulty of current high-level hepatectomy certificated by the Japanese Society of Hepato-Biliary-Pancreatic Surgery.

BACKGROUND: The current high-level hepatectomy (HLH) is certified by the Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS), comprising only anatomical hepatectomies above Couinaud's segmentectomy. This multicenter study aimed to identify the conditions of non-HLH that satisfy equivalent technical difficulties to HLH. METHODS: Between 2018 and 2021, 595 first open hepatectomies without biliary reconstruction (374 HLHs and 221 non-HLHs) were performed in the five institutions. Non-HLHs belonging to at least one of the three conditions; depth of hepatectomy ≥5 cm, number of resections ≥3 locations and at least one location with a depth of hepatectomy ≥3 cm, and hepatectomy involving the paracaval portion of the caudate lobe was proposed as the candidate for difficult non-HLH. The technical difficulty was estimated by the operative time and blood loss. RESULTS: Difficult non-HLHs were neither associated with shorter operative time (373 min vs. 354 min, p = .184) nor lesser blood loss than those with HLHs (503 mL vs. 436 mL, p = .126). Postoperative complications such as Clavien-Dindo classification grade III or more were not significant between the two groups (18.6% vs. 13.4%, p = 0212). CONCLUSIONS: Difficult non-HLHs were associated with no lesser technical difficulty than those with HLH.