Association between surgical difficulty and tumor location based on subsegments of the Glisson branches in...

Laparoscopic liver resection has a steep learning curve, and multiple difficulty-scoring systems have been proposed to support safe implementation. Though the IWATE scoring system is widely used, the rationale for its tumor location score is unclear. The objective of our study was to establish a more accurate definition of tumor location based on subsegments of the Glisson branches.

We included 176 patients who underwent laparoscopic liver resection between January 2017 and February 2024, excluding those who underwent multiple or concomitant resections of other organs. Tumor location was defined by the most proximal subsegment of the Glisson branches (1sp, Spiegel; 1pc, para-caval; 1cp, caudate process; 3a, apical; 3b, basal; 4a; 4b; 5v, ventral; 5d, dorsal; 6v; 6d; 6 L, lateral; 7v; 7d; 8v; 8d).

Within each segment, comparing operative time between subsegments showed significant differences, except for S1 (3a vs. 3b, p = 0.011; 4a vs. 4b, p = 0.001; 5v vs. 5d, p = 0.012; 6v vs. 6d vs. 6 L, p = 0.007; 7v vs. 7d, p = 0.003; 8v vs. 8d, p = 0.030). Blood loss significantly differed except for S1 (3a vs. 3b, p = 0.018; 4a vs. 4b, p = 0.002; 5v vs. 5d, p = 0.016; 6v vs. 6d vs. 6 L, p = 0.011; 7v vs. 7d, p = 0.013; 8v vs. 8d, p < 0.001). The incidence of postoperative complications did not differ significantly; however, hospital stay was significantly different only in S4 (4a vs. 4b, p = 0.049).

There are significant differences in the difficulty of laparoscopic liver resection among subsegments. More detailed scoring based on subsegments may improve accuracy, and we propose a new scoring system.