General anesthesia is utilized for segmental liver resection. The aim of performing a segmental or sectorial resection is to remove a solitary benign or malignant liver lesion, although several lesions may be amenable to segmental resection or to treat segmental biliary strictures, trauma, or abscess. The goal is to achieve negative margins around tumor(s), as well as excising any liver parenchyma devascularized from occlusion of segmental portal inflow. Segmental resections can be combined with a contralateral major hepatectomy for complete resection of bilateral disease. Segmental resection is also used in patients with underlying liver dysfunction (e.g., cirrhosis, steatosis, or fibrosis) at risk of liver failure who would not tolerate a major liver resection. Segmental or sectorial resection is commonly utilized in patients with solitary hepatocellular carcinoma or in patients with a single metastasis (e.g., colorectal carcinoma, melanoma).

The anatomical points in the performance of segmentectomy or sectorectomy is primarily dictated by the possible variant inflow that can occur with the right lobe of the liver. The right hepatic inflow that supplies segments 5, 6, 7, and 8 arises from the junction of the right and left portal vein. In a majority of cases, there is a common right portal vein that branches into the right anterior sectorial and right posterior sectorial branches (Fig. 8.2a). However, the main right portal vein leading to the right anterior and right posterior sectorial branches may be absent, instead originating at the same junction as the left portal vein (Fig. 8.2b). Another main portal anatomical points can occur with the early takeoff of the right posterior sectorial vein, with the bifurcation then occurring at the left portal vein and the right anterior sectorial vein (Fig. 8.2c). Inflow within the right hepatic lobe can also vary with segment-6 inflow branches originating from the anterior sectorial branches and creating an isolated segment-7 branch (Fig. 8.2d). This anatomical point is important to ensure that only a single segment of inflow is occluded instead of the entire right lobe or the anterior or posterior segment, respectively.

See Table 8.1. Potential major complications of hepatic resection are bleeding and biliary leakage. Bleeding during segmentectomy and sectorectomy will occur primarily from the outflow hepatic veins. These are thin walled veins that tear easily and can develop lateral tears, which can extend up to the main venous branches or to the inferior vena cava underneath intact hepatic parenchyma. Thus, any form of segmentectomy or sectorial resection must identify all of the major hepatic venous outflow structures to ensure adequate hemostasis and to minimize blood loss. Biliary leakage is primarily a problem in patients who are undergoing some form of bile duct resection and requiring biliary reconstruction (Tanaka et al. 2002). Biliary leakage is less common when performing a segmentectomy or sectorectomy and primarily will occur because of the inadvertent transection of a (small) bile duct without adequate closure. The performance of a segmentectomy should not be automatically assumed to be a lesser operative procedure compared to hepatic lobectomy or some form of extended hepatic lobectomy, since the anatomical relationships may be more complex to appreciate and the resections can be technically more demanding than lobectomies. Recent evaluations have shown that intraoperative blood loss is significantly greater when a nonanatomical resection is performed, compared to an anatomical hepatic segmentectomy or lobectomy, principally because of difficulty with small venous outflow control during resection. Nonanatomical resection is also associated with a higher margin positivity rate (DeMatteo et al. 2000). All segmental resections are not of similar difficulty. A segment-3 resection is technically more straightforward compared to a segment-8 resection. The accessibility of the inflow and outflow structures, the presence of variant anatomy, the depth and quality of the liver parenchyma, and the patient body habitus can make various types of segmental resections more difficult in certain patients.