Akihiko Horiguchi

Couinaud’s eight-segment model remains the universal language of liver surgery; however, contemporary multidetector computed tomography (CT), three-dimensional (3D) reconstruction, and minimally invasive surgery have exposed substantial variability in third-order or more peripheral portal branching. This variability becomes clinically important when hepatocellular carcinoma and other liver malignancies are treated with small, parenchymal-sparing anatomical resections, where third-order or more peripheral portal territories define the oncologic unit at risk. This review examines the current evidence of surgical anatomy relevant to liver surgery, focusing on third-order portal branches and comparing classical Couinaud segmentation with CT/3D reconstruction-based portal territories. Clinically relevant variations in the right anterior (S5/S8) and right posterior (S6/S7) sections are described, while the more limited and heterogeneous evidence for the left hemiliver is explicitly acknowledged. In the right anterior section, craniocaudal, ventrodorsal, trifurcation, and other branching patterns may alter the practical interpretation of S5/S8 anatomy. In the right posterior section, bifurcation and loop-type portal configurations have distinct implications for S6/S7-oriented resection and individual anatomy-based resection. Comparable variability in the left hemiliver, particularly around the umbilical portion and segment 4 branches, further supports individualized preoperative territory mapping. A two-level anatomical planning framework is proposed as a conceptual strategy: Couinaud-based anatomy for first- and second-order resection and individualized CT-based anatomy for third-order or more peripheral resection. This framework is supported by anatomical observations and technical feasibility, but it has not been shown to improve perioperative or oncological outcomes. Evidence supporting anatomical liver resection in general should not be regarded as direct validation of cone-unit (small portal territory) resection, which requires prospective and independent clinical evaluation. The current status of preoperative simulation and intraoperative implementation using ultrasound, indocyanine green fluorescence, and navigation/fusion technologies is discussed. Finally, emerging directions, including automated vessel segmentation and AI-assisted territory analysis, are considered.

Biliary tract cancer (BTC) surgery often requires more than organ resection, and the role of minimally invasive surgery (MIS) cannot be adequately interpreted by disease subtype alone because operative complexity varies substantially within each subtype. This narrative review evaluates recent evidence for laparoscopic and robotic surgery in BTC from a task-based perspective, focusing on liver resection, lymphadenectomy, bile duct resection and reconstruction, vascular or multivisceral procedures, and pancreatic resection. Peripheral intrahepatic cholangiocarcinoma, which is often of the small-duct type, represents the most established field for minimally invasive liver resection, although lymphadenectomy remains inconsistent. Central intrahepatic cholangiocarcinoma, which is often of the large-duct type, should be considered separately because increasing hilar involvement may require systematic lymphadenectomy and bile duct resection and reconstruction, making the operation more similar to that for perihilar cholangiocarcinoma. Perihilar cholangiocarcinoma remains the highest-task-load frontier of BTC-MIS, typically requiring major liver resection with caudate lobectomy, bile duct resection, lymphadenectomy, and reconstruction of multiple small bile ducts. Current evidence is derived predominantly from retrospective studies of highly selected patients treated at expert centers. Gallbladder cancer should be stratified into Tis/T1a disease, T1b/T2 and selected T3 disease suitable for standard extended cholecystectomy, bile duct-involved disease, and locally advanced disease. Distal cholangiocarcinoma should be evaluated within the evidence base for minimally invasive pancreaticoduodenectomy rather than liver surgery. Overall, current evidence most strongly supports MIS for selected patients with peripheral intrahepatic cholangiocarcinoma and for standard extended cholecystectomy in selected patients with gallbladder cancer. Minimally invasive pancreaticoduodenectomy may also be considered for selected patients with distal cholangiocarcinoma in experienced centers. Central intrahepatic cholangiocarcinoma, perihilar cholangiocarcinoma, bile duct-involved gallbladder cancer, and locally advanced gallbladder cancer require cautious patient selection, standardized reporting, and prospective multicenter validation.

Couinaud’s eight-segment model remains the universal language of liver surgery, yet contemporary multidetector computed tomography (CT), its three-dimensional (3D) reconstruction, and minimally invasive surgery have exposed substantial variability in third-order or more peripheral portal branching. This variability becomes clinically important when hepatocellular carcinoma and other liver malignancies are treated with parenchymal-sparing small anatomical resections where third-order or more peripheral portal territories define the oncologic unit at risk. In this article, the current surgical anatomy for liver cancers was reviewed focusing at third-order portal branches, comparing classical Couinaud segmentation with CT/3D reconstruction-based portal territories. Clinically relevant variability in the right anterior (S5/S8) and right posterior (S6/S7) sections are described while also highlighting that comparable discordance exists in the left hemi-liver. In the right anterior section, craniocaudal, ventrodorsal, trifurcation, and other branching patterns may alter the practical interpretation of S5/S8 anatomy. In the right posterior section, bifurcation and loop-type portal configurations have distinct implications for S6/S7-oriented resection and cone-unit-based anatomical resection. Comparable variability in the left hemiliver, particularly around the umbilical portion and segment 4 branches, further supports individualized preoperative territory mapping. A pragmatic two-tier surgical strategy is proposed; Couinaud-based resection for first/second-order anatomy and individualized CT-guided cone-unit resection for third-order or more peripheral anatomy. Current status of preoperative simulation and intraoperative implementation using ultrasound, indocyanine green fluorescence, and navigation/fusion technologies are discussed. Finally, emerging directions including automated vessel segmentation and AI-assisted territory analysis are also discussed.

Anastomotic leakage (AL) and pelvic sepsis remain important causes of morbidity after restorative rectal cancer surgery, affecting mortality, stoma-free survival, bowel function, and oncologic treatment. Reported rates after low anterior resection are approximately 5–20%. We conducted a structured narrative review of PubMed/MEDLINE and the Cochrane Library through 20 July 2026, focusing on prevention, recognition, source control, and long-term recovery after low pelvic reconstruction. Most biological requirements for healing and principles of source control are approach-agnostic, whereas open, laparoscopic, and robotic surgeries create different technical conditions for pelvic exposure, stapler trajectory, articulation, tactile feedback, conversion, and fluorescence imaging. This review therefore integrates approach-specific technical constraints with post-discharge recognition, anatomy-based source control, and patient-centered long-term outcomes rather than treating these domains separately. Among preventive measures, combined mechanical bowel preparation and oral antibiotics has the strongest support in elective, non-obstructed patients; indocyanine green fluorescence is a useful adjunct when perfusion is uncertain but does not replace assessment of tension or mechanical integrity. C-reactive protein is mainly useful for ruling out major complications, whereas contrast-enhanced computed tomography remains first-line imaging and pelvic magnetic resonance imaging is best reserved for selected small defects, chronic sinuses, or complex pelvic sepsis. Management should be driven first by physiology and then by leak timing and location, defect size, conduit viability, diversion status, and cavity drainability. Durable success includes sepsis control, anatomical healing, stoma reversal when feasible, and acceptable long-term function.

Background: Classical Couinaud’s segmentation assumes the dichotomous division of the right posterior portal vein (RPPV) into P6 and P7. However, increasing imaging evidence suggests substantial anatomical variability, limiting the intraoperative identification of segmental borders and providing guidance for subsegmental resection. Methods: We retrospectively analyzed contrast-enhanced five-phase computed tomography (CT)-based three-dimensional reconstructions from 100 consecutive eligible cases (2020–2025). Third-order RPPV branching patterns were classified into three types: bifurcation (PV-type 1), loops (PV-type 2), and others (PV-type 3). We measured the 3D distances from the posterior portal origin to the first major branch point and performed volumetric analysis of territories supplied by individual third-order branches using Ziostation REVORAS. Hepatic vein anatomy was categorized as HV-type 1 (a fissure plane forming an intersegmental vein), HV-type 2 (a landmark vein without plane formation), or HV-type 3 (neither) and compared between portal types. Results: PV-type 1 was observed in 45 cases (45.0%), while PV-type 2 was seen in 53 cases (53.0%); however, two cases (2.0%) showed other patterns. The distance to the first branch point was shorter in PV-type 1 than in PV-type 2 (8.89 ± 7.87 vs. 17.3 ± 8.36 mm; p < 0.001). In PV-type 1, the first caudal branch territory (corresponding to S6) accounted for 43.8% ± 12.6% of the posterior section, whereas the first-branch cone-unit territory in PV-type 2 accounted for 14.9% ± 8.64% (p < 0.001). The HV-type 1/2/3 ratios differed by portal type (PV-type 1: 29/16/0; PV-type 2: 25/14/14; p < 0.001), and 26.4% of PV-type 2 cases lacked any hepatic venous landmarks. Conclusions: PV-type 2 peripheral RPPV branching was observed in 53% of cases. Although conventional Couinaud-based segmentectomy with the Glissonian approach and vein-guided transection was suitable for PV-type 1, cone-unit-based anatomical resection supported by individualized preoperative simulation and intraoperative navigation may prove useful for PV-type 2 anatomy.

The presence of portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) is widely recognized as one of the most critical determinants of tumor progression and prognosis

Biliary tract cancer (BTC) remains challenging disease in which complete surgical resection often with liver resection is the only curative treatment. Although minimally invasive surgery (MIS) has become established in liver resection, its adoption for BTC has been deliberately cautious because oncologic BTC surgery often requires a demanding combination of major liver resection, regional lymphadenectomy, bile duct resection and reconstruction, and occasionally vascular resection and reconstruction. This narrative review evaluates recent advances in laparoscopic and robotic surgery for BTC from the perspective of liver surgery, emphasizing how procedure-specific tasks should define the role and expansion of MIS in each disease which belongs to BTC. Intrahepatic cholangiocarcinoma currently represents the most mature field for minimally invasive liver resection, whereas perihilar cholangiocarcinoma remains the most complex frontier because of multi-duct biliary reconstruction and potential vascular involvement besides major liver resection with caudate lobectomy. For gallbladder cancer, MIS has evolved from a historical contraindication toward selected oncologic extended resections, while distal cholangiocarcinoma is increasingly discussed within the expanding evidence base for minimally invasive pancreaticoduodenectomy. Across subtypes, robotics may add value to lymphadenectomy, hilar dissection and biliary-enteric reconstruction by improving dexterity and three-dimensional visualization. However, current evidence remains limited by retrospective study designs, selection bias, heterogeneous reporting, and insufficient long-term oncologic data. Future progress should be therefore based on centralization, structured training, prospective registries, and standardized quality metrics, including margin status, nodal yield, conversion, morbidity, time to adjuvant therapy, timing and pattern of recurrence, and overall survival.

Background/Objectives: Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal gastrointestinal cancers, and reliable preoperative predictors of aggressive tumor biology are essential for optimizing treatment strategies, particularly in resectable PDAC (RPDAC). This retrospective study evaluated the diagnostic accuracy of dynamic computed tomography (CT) for detecting extrapancreatic extension, peripancreatic plexus (PL), serosal (S), and retroperitoneal (RP) invasion, and assessed its prognostic significance. Methods: Ninety-four patients who underwent curative-intent upfront surgery for resectable PDAC between 2007 and 2020 were included. Dynamic CT was reviewed using standardized window settings (WL 35/WW 350) to identify soft-tissue projections extending beyond the pancreatic contour. Results: Pathological S, RP, and PL invasion occurred in 29.8%, 56.3%, and 17.0% of patients, respectively. Dynamic CT demonstrated accuracies of 73.4%, 76.6%, and 87.2% for S, RP, and PL invasion, respectively. Notably, patients with PL-positive CT findings had significantly poorer disease-specific survival (DSS) than those with PL-negative, with 3- and 5-year DSS rates of 37% and 0% versus 61% and 53% (p < 0.001). Multivariate analysis confirmed preoperative PL invasion as the only independent predictor of poor prognosis. Conclusions: Dynamic CT provides reasonable diagnostic performance for assessing extrapancreatic invasion. In addition, CT-identified PL invasion reflects aggressive tumor behavior and may justify consideration of neoadjuvant therapy, even in anatomically resectable disease.

Aim: Minimally invasive anatomic liver resection (AR) is technically demanding, and the efficacy of robotic surgery in AR remains unestablished. This systematic review aims through a meta‐analysis to compare surgical outcomes between robotic (RAR) and conventional laparoscopic (LAR) AR. Methods: A systematic literature search of relevant studies published between 2001 and 2024 in PubMed/MEDLINE, Embase and Cochrane Library was carried out, and 15 studies were selected. Meta‐analysis was performed to compare perioperative outcomes between RAR and LAR. Results: A total of 4171 patients comprising 2042 RAR and 2129 LAR patients who underwent major hepatectomy or liver parenchyma‐sparing AR (PSAR) were included. All included studies were retrospective comparative studies, including eight using propensity score‐matched analysis. Meta‐analysis demonstrated that as primary outcomes, the 30‐day and 90‐day mortalities and postoperative overall morbidity were comparable between RAR and LAR, while RAR had significantly less morbidity≥Clavien‐Dindo grade II and a lower rate of open conversion. As secondary outcomes, compared to LAR, RAR showed significantly less blood loss and shorter postoperative hospital stay, while RAR had a higher rate of postoperative 30‐day readmission. Operative time, blood transfusion, Pringle maneuver, R0 resection, and reoperation were comparable. Subgroup meta‐analyses showed a lower rate of blood transfusion in robotic PSAR and a lower rate of open conversion in RAR in the right cranial regions. Conclusion: This large‐scale meta‐analysis of minimally invasive AR suggests that RAR can confer comparable or partly better perioperative outcomes as compared to LAR, indicating potential advantages of the robotic approach to AR.

Background/Objectives: Duodenum-preserving pancreatic head resection (DPPHR) preserves digestive and absorptive functions better than pancreaticoduodenectomy (PD). Zinc is primarily absorbed in the duodenum and proximal jejunum and plays a critical role in nutritional maintenance and pancreatic regeneration. However, no studies have compared the postoperative pancreatic volume and serum zinc levels between DPPHR and PD. Methods: We retrospectively analyzed 41 patients who underwent DPPHR (n = 23) or subtotal stomach-preserving PD (n = 18) for low-grade pancreatic malignancies at our institution. The remnant pancreatic volumes on postoperative day 7 and 1 year were measured via computed tomography. Nutritional parameters, including serum albumin, prognostic nutritional index (PNI), and serum zinc levels, were compared between the groups. Serum zinc levels were evaluated in patients with DPPHR (n = 11) or PD (n = 7). Results: The DPPHR group demonstrated significantly better preservation of remnant pancreatic volume on postoperative day 7 and 1 year compared to the PD group (p = 0.045 and p = 0.041, respectively). Volume maintenance ratios were also significantly higher in the DPPHR group. Serum albumin levels at 1 year postoperatively were significantly better in the DPPHR group, although no significant difference was found in the PNI. Among patients evaluated for serum zinc, the DPPHR group showed significantly higher zinc levels compared to the PD group (80.3 vs. 65.8 μg/dL, p = 0.017). Conclusions: DPPHR preserves remnant pancreatic volume and maintains serum zinc levels better than PD, potentially contributing to improved postoperative nutritional status and quality of life. Further prospective studies with larger cohorts are warranted to validate these findings.