CHAPTER 13 Hepatectomy
BACKGROUND
A variety of liver resections are commonly performed, including limited resections (e.g., tumor enucleation or wedge resection) and anatomic resections (i.e., removal of a segment or lobe of the liver). The extent of hepatic resection undertaken is, in part, dictated by the type of pathology and its anatomic location. Additionally, the choice of operation depends on the patient’s hepatic reserve. Up to 80% of the liver parenchyma can be removed from a normal liver because the remaining segment will hypertrophy and hepatic function will be restored within days to weeks. In the presence of underlying liver disease, however, significantly less liver parenchyma can be safely removed. The Child’s classification and its modifications are commonly used to assess a patient’s hepatic functional reserve (Table 13-1). In patients classified as Child’s class C, hepatic resection should not be attempted because of the very high risk of postoperative liver failure. Even in patients with well-compensated cirrhosis who are classified as Child’s class A, only limited hepatic resection should be performed.
INDICATIONS FOR HEPATECTOMY
I. Neoplasm: The majority of liver resections in the United States are performed for malignant disease, most commonly for metastatic cancer. Additionally, the increasing burden of hepatocellular carcinoma (HCC) in the United States because of chronic hepatitis C virus infection and cirrhosis has made liver resection and transplantation for HCC more common. In contrast, hepatic resection for cholangiocarcinoma remains relatively uncommon because the majority of patients with this malignancy present with advanced, unresectable disease.
A. Malignant Neoplasms
1. Metastatic cancer: The liver is the first site of metastases in most patients with advanced colorectal cancer. The 5-year survival rate is improved by hepatic resection in appropriately selected patients with colorectal metastases. Generally, patients with three or fewer lesions confined to one lobe of the liver are considered candidates for resection, as are patients with more than three lesions that shrink in response to chemotherapy. Hepatic resection of metastases is rarely beneficial unless it renders the patient free of disease. Contraindications to partial hepatectomy include: (1) involvement of more than six of the eight anatomic liver segments with tumor, (2) involvement of more than 70% of the liver, and (3) involvement of all three hepatic veins. Although optimal margins for resection have not been clearly defined, some studies suggest that patients who undergo anatomic resection (i.e., resection of a lobe or segment of the liver) have superior outcomes compared with those who receive wedge resection. Combinations of resection with local ablative techniques (e.g., radiofrequency ablation) have also been explored for the treatment of patients with multiple metastases.
2. Hepatocellular carcinoma: The surgical management of HCC is frequently complicated by the presence of cirrhosis. Patients who have limited disease and undergo expeditious liver transplantation have superior disease-free survival compared with those who undergo hepatic resection. The United Network for Organ Sharing (UNOS) prioritizes patients who have HCC for transplantation on the basis of the Milan criteria; these include solitary tumors smaller than 5 cm or three or fewer masses, each less than 3 cm in size. Currently, most patients who receive priority listing receive transplants within 90 to 120 days. In contrast, limited resection should be considered in patients with well-compensated cirrhosis (i.e., Child’s class A or no portal hypertension). In the absence of cirrhosis, anatomic hepatic resection is the treatment of choice for HCC (Fig. 13-1).
3. Cholangiocarcinoma: Cholangiocarcinomas are malignancies of the biliary epithelia. These tumors may be classified as intrahepatic, perihilar, or distal extrahepatic. Surgical resection of the bile duct and associated hepatic parenchyma affords the only chance for cure. However, because of their aggressive nature, a minority (<10%) of these tumors are resectable. Partial hepatectomy is indicated in patients with intrahepatic or perihilar disease, whereas pancreaticoduodenectomy (i.e., Whipple procedure) is performed in patients with resectable distal disease.
B. Benign neoplasms: The majority of liver masses are benign. Most are discovered incidentally and do not require resection in the absence of symptoms. The most common benign tumors are hemangiomas, focal nodular hyperplasia, and adenomas. Hepatic adenomas are associated with a risk of spontaneous intra-abdominal hemorrhage and malignant degeneration and sometimes require resection. Adenomas have been linked to the use of oral contraceptives (OCPs), and discontinuation of these agents constitutes first-line therapy. Indications for resection of adenomas include size greater than 2 cm in the absence of OCP use and subcapsular location. Enucleation or wedge resection is usually adequate therapy.
II. Infection: Infection is a rare indication for hepatic resection. Percutaneous drainage of liver abscesses has supplanted hepatic resection and open surgical drainage in the majority of cases of bacterial or fungal infection. However, hepatic resection still plays an important role in the management of parasitic cystic diseases of the liver. Some cysts are treated with drainage and obliteration of the cyst cavity or total cyst excision (pericystectomy). These more conservative surgical procedures are not appropriate for the treatment of large intrahepatic echinococcal cysts (hydatid cysts). Although patients with hydatid cysts are generally treated with albendazole, in many patients, medical treatment is unsuccessful and surgery is required. Such cysts are best treated with partial hepatectomy to avoid spillage of the cyst contents into the peritoneal cavity, which is associated with disseminated cystic disease and a risk of anaphylaxis.
III. Living-Related Liver Transplantation: Living-related liver transplantation has evolved in response to the severe shortage of organ donors. The donation of liver lobes from adults into pediatric recipients has been widely practiced since the 1980s. These operations typically involve resection and transplantation of a small left lateral segment. Living-related transplantation is more challenging in adults because of the requirement for greater hepatic mass. Right hepatic lobectomy is usually necessary to provide sufficient liver volume.
PREOPERATIVE EVALUATION
I. Radiographic Evaluation: Contrast-enhanced CT scan and magnetic resonance imaging (MRI) are the imaging modalities of choice during the planning of a partial hepatectomy. The extent of involvement of venous, arterial, and biliary structures in the potential resection specimen must be delineated. Cross-sectional imaging techniques, such as magnetic resonance angiography and magnetic resonance cholangiography, can also be extremely useful for preoperative planning, particularly for living-related donor hepatectomy. Additionally, volumetric CT and MRI
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