A suitable animal model for laparoscopic hepatic resection training

Background: There is a growing interest in using laparoscopy for hepatic resection. However, structured training is lacking in part because of the lack of an ideal animal training model. We sought to identify an animal model whose liver anatomy significantly resembled that of the human liver and to assess the feasibility of learning laparoscopic hepatic inflow and outflow dissection and parenchyma transection on this model. Methods: The inflow and outflow structures of the sheep liver were demonstrated via surgical dissection and contrast studies. Laparoscopic left major hepatic resections were performed. Results: The portal hepatis of all 12 sheep (8 for anatomic study and 4 for laparoscopic hepatic resection) resembled that of human livers. The portal vein (PV) was located posteriorly; the common hepatic artery (CHA) and the common bile duct (CBD) were located anterior medially and anterior laterally with respect to the portal hepatis. The main PV bifurcated into a short right and a long left PV. The extrahepatic right PV then bifurcated into right posterior and anterior sectoral PV. The CBD and CHA bifurcated into left and right systems. The cystic duct originated from the right hepatic duct. The cystic artery originated from the right HA in 11/12 animals. The left hepatic vein drained directly into the inferior vena cava (IVC). The middle and the right hepatic veins formed a short common channel before entering the IVC. Multiple venous tributaries drained directly into IVC. Familiarity with sheep liver anatomy allowed laparoscopic left hepatic lobe (left medial and lateral segments) resection to be performed with accuracy and preservation of the middle hepatic vein. Conclusions: The surgical anatomy of sheep liver resembled that of human liver. Laparoscopic major hepatic resection can be performed with accuracy using this information. Sheep is therefore an ideal animal model for advanced surgical training in laparoscopic hepatic resection.