OBJECTIVE(S): The technical complexity of laparoscopic liver resection (LLR) poses unique challenges distinct from open surgery. An objective scoring system was developed that preoperatively quantifies the difficulty of LRR to help guide surgeon decision-making regarding the feasibility and safety of minimally invasive approaches. The aim of this multiinstitutional study was to externally validate this scoring system. METHODS: Patients who underwent LLR at two institutions were reviewed. LLR difficulty score (LDS) was calculated based on patient, tumor, and anatomic characteristics by two independent, blinded hepatobiliary surgeons. Surrogates of case complexity (e.g., conversion rate, operative time) were used for validation of this index. RESULTS: From 2006 to 2016, 444 LLR were scored as low (n = 94), intermediate (n = 98), and high difficulty (n = 152) with respective conversion rates of 5.3%, 15.7%, and 25%. Cases of higher LDS correlated with larger mean blood loss (203 ml vs. 331 ml vs. 635 ml). Mean operative and Pringle maneuver used were associated with increasing LDS (155 min vs. 202 min vs. 315 min and 14.4% vs. 29.7% vs. 45.1% respectively). These operative surrogates of difficulty correlated significantly with the LDS (all p < 0.0001). CONCLUSIONS: This comprehensive external validation of the LDS is robust and applicable in diverse patient populations. This LDS serves as a useful objective predictor of technical difficulty for LLR to help surgeons in selecting patients according to their individual operative experience and is valuable for preoperative risk estimation and stratification in randomized trials.
