The Importance of Segment 4 Anatomy on Outcomes Following Living Donor Left Lateral Segmentectomy

Background: During left lateral section (LLS) resection for live liver donation, the vascular inflow and the bile drainage of segment 4 (S4) are compromised. We investigated the long-term changes of S4 after donation and their potential prognostic impact on living liver donors. Materials and methods: This was a retrospective analysis of 42 consecutive left lateral (LLS, S2/3) liver resections for living donation. Results: There were 25 female and 17 male donors. Median age was 33 y and median body mass index was 26. Median LLS, S2/3, volume was 262 cc, and median sS4 volume was 160 cc. Complications were encountered in three donors (7%). An independent extrahepatic S4 artery (S4A) (with a proximal left heptic artery or a right hepatic artery origin) was identified in 41% of the donors. Ligation of the independent S4A was not associated with the rate of post resection liver dysfunction, complications, or the degree of S4 atrophy. Having a dominant S4 portal triad pedicle feeding the right anterior sectors, segment 5/8, of the liver was associated with increased parenchymal damage as evidenced by a higher peak of alanine aminotransferase but was not associated with postoperative complications. The median degree of atrophy of S4 at 1 y post donation as noted on imaging was 66%. The presence of a dominant S4 portal triad pedicle and the peak alanine aminotransferase early postoperatively were both predictors of the degree of S4 atrophy post donation. Conclusions: The presence of an independent S4A or dominant S4 portal triad pedicle feeding the liver right anterior sectors, segment 5/8, should not be a contraindication for left lateral segment living donation.