Liver anatomy for totally laparoscopic segment 7 resection from a caudal magnified view–a 3-dimensional computed tomographic analysis

Laparoscopic resection of hepatic segment 7 is considered particularly difficult. We analyzed anatomic variation of this segment in caudally oriented 3-dimensional (3D) magnified computed tomographic (CT) images obtained prior to liver resection.

Analysis included 105 patients with preoperative 3D CT evaluation preceding liver resection for hepatobiliary malignancies between April 2021 and April 2024.

Five ramification patterns were evident from a caudal magnified view. Some patients who had multiple segment 7 (S7) portal pedicles and an S7 pedicle branching ventrally posed difficulty in performing segmentectomy for the exact extent of S7. Distance from the point where a perpendicular line from the right rim of the inferior vena cava (IVC) intersected the right posterior portal pedicle to the point of bifurcation of the S6 and 7 pedicles was 34.6 mm (range, 3.9–78.8; mean ± standard deviation, 35.2 ± 14.8 mm). The median angle between the perpendicular line from the right rim of the IVC and the line from the root of the S7 pedicle to the right rim of the IVC was 77° (10–140); the mean ± standard deviation was 75.3° ± 28.1. Differences among ramification patterns also were evident. The angle between the right posterior portal pedicle and the S7 pedicle was 143° (79–215) or 143.3 ± 26.7, and that between S7 and S6 pedicles was 71°(15–123) or 75.5 ± 21.7°, representing relatively little variation.

Understanding these details of caudal-view anatomy may resolve difficulties and clarify access required for exposing S7 portal pedicles.