Hepatectomy inside the Portal Ring in a Patient with Absence of Portal Vein Bifurcation: A Case Report.

INTRODUCTION: Absence of portal vein bifurcation (APB) is a rare congenital anomaly in which the main portal vein does not bifurcate at the hepatic hilum. After giving off posterior and anterior sectoral branches, the trunk curves ventrally around the middle hepatic vein-forming a so-called "portal ring"-and finally enters the umbilical portion of the left portal vein. Hepatectomy performed inside this ring risks compromising perfusion if the portal trunk is injured. We report a case in which anatomical segmentectomy (S4a+S5) was performed for the gallbladder carcinoma with this portal vein anomaly.

CASE PRESENTATION: A 69-year-old man presented with 1 month of epigastric pain. Imaging revealed gallbladder carcinoma invading the gallbladder bed and liver parenchyma, together with APB confirmed by 3D reconstruction. Based on preoperative simulation, we performed anatomical resection of segments 4a and 5 with lymphadenectomy. Intraoperative ultrasonography verified the portal ring anatomy; the anterior Glissonean pedicle (G5) was ligated and the demarcation line was followed for parenchymal transection under intermittent Pringle maneuver (total ischemic time 70 minutes). Operative time was 6 hours 3 minutes, and blood loss 170 mL. Pathology showed nodular gallbladder carcinoma (UICC 8th: pT3a, pN1 [#8p, #12a], cM0; Stage IIIB) with negative margins. The postoperative course was uneventful and the patient was discharged on day 12.

CONCLUSIONS: Preoperative 3D simulation and meticulous intraoperative ultrasonography enabled safe hepatectomy inside the portal ring without compromising portal perfusion. In APB, right-sided major hepatectomy may jeopardize global portal inflow; tailored anatomical resection (S4a+S5) achieved an R0 resection while preserving perfusion.