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 allow measurement of hepatic volume and can assist in estimating postoperative remnant volume before planned partial hepatectomy.
II. Laboratory Evaluation: Liver function may be estimated by serologic tests, including LFTs (serum aspartate aminotransferase [AST], alanine aminotransferase [ALT], total bilirubin, and alkaline phosphatase) and coagulation parameters (PT, PTT, INR). Albumin may be used as a marker of long-term protein production, and thrombocytopenia may reflect hypersplenism and portal hypertension. Serum α-fetoprotein levels can be useful in confirming the diagnosis of HCC and can be followed after resection to detect recurrence.
III. Tests of Metabolic Capacity: A variety of tests can be performed to more accurately assess physiologic hepatic function. Tests that measure protein synthesis, microsomal and cytosolic function, hepatic perfusion, and functional hepatocyte mass are available at some centers. Clearance of indocyanine green from the bloodstream can be used to assess hepatic function and has been shown to predict hospital mortality and survival rates after hepatic resection in patients with cirrhosis. Other tests that measure quantitative hepatic metabolic capacity include erythromycin breath tests, galactose elimination capacity, and salivary caffeine clearance.
IV. Liver Biopsy: Biopsy of the liver can provide important information about the presence or absence of normal hepatic architecture, fibrosis, cirrhosis, and fatty infiltration. Liver histology can be helpful preoperatively in determining how much liver can be resected (Fig. 13-2).
COMPONENTS OF THE PROCEDURE AND APPLIED ANATOMY
Resection Nomenclature
Cantlie’s line divides the liver into the right hemiliver (segments V–VIII) and the left hemiliver (segments II–IV), which are the segments that are commonly resected during right and left hepatectomy, respectively. Resection of the hepatic parenchyma to the left of the falciform ligament (segments II and III) is called left lateral segmentectomy. Resection of the hepatic parenchyma to the right of the falciform ligament (segments IV–VIII) has multiple names, including extended right hepatectomy, right trisegmentectomy, and right lobectomy, depending on which nomenclature system is used (Fig. 13-3 and Box 13-1). Other limited anatomic resections, including specific segmental resections that follow the segmental anatomy of the liver, can be performed as well. During nonanatomic wedge resections, the parenchyma and vessels are divided without consideration of the internal hepatic anatomy. Wedge resections are most commonly used for small peripheral tumors in patients with benign disease or in patients with malignant disease who cannot tolerate a formal lobectomy.
BOX 13-1
Nomenclature of Hepatic Resections
| Couinaud (1957) | Goldsmith and Woodburne (1957) |
|---|---|
| Right hepatectomy (segments V, VI, VII, VIII) | Right hepatic lobectomy |
| Left hepatectomy (segments II, III, IV) | Left hepatic lobectomy |
| Right lobectomy* (segments IV, V, VI, VII, VIII) | Extended right hepatic lobectomy* |
| Left lobectomy (segments II, III) | Left lateral segmentectomy |
| Extended left hepatectomy† (segments II, III, IV, V, VIII) [see Fig. 13-3B] | Extended left lobectomy† |
* Also referred to as a right trisegmentectomy (Starzl, 1975, 1980).
† Also referred to as a left trisegmentectomy (Starzl, 1982).
Data from Blumgart LH [ed]: Surgery of the Liver, Biliary Tract, and Pancreas, 4th ed. Philadelphia, Saunders, 2007.
Preoperative Considerations
I. Preoperative antibiotics that cover gram-positive and gram-negative organisms are given within 1 hour before incision.
II. Urinary catheterization is indicated to decompress the bladder and monitor intraoperative and postoperative volume status.
IV. Liver resections may be associated with substantial blood loss, large fluid requirements, and wide fluctuations in blood pressure. Arterial lines are commonly indicated to allow for continuous blood pressure monitoring. Central venous catheters are often inserted to provide durable venous access and allow for the assessment of volume status.
Incision and Exposure
I. Although most hepatic resections can be performed through a right subcostal incision, additional exposure sometimes requires midline or left subcostal extension. Very rarely, a median sternotomy is required to access the intrapericardial inferior vena cava (IVC) (Fig. 13-4).
II. The abdominal cavity is entered, and the abdomen is explored. The liver is evaluated by inspection and bimanual palpation.
III. In many circumstances, especially in patients with malignant disease, an intraoperative ultrasound is useful in confirming the findings of preoperative studies and determining the relationship of the tumor to major vascular structures within the hepatic parenchyma. Enlarged lymph nodes may be sent for frozen section examination to rule out extrahepatic metastases.
IV. The liver is mobilized by selectively dividing its peritoneal attachments. For most resections, the liver is mobilized from the anterior abdominal wall by dividing the falciform ligament (Fig. 13-5).
V. The liver’s attachments to the diaphragm, including the right and left triangular ligaments, are selectively divided, depending on the portion of the liver to be removed (Figs. 13-6 and 13-7). If an anterior wedge resection is to be performed, these ligaments do not have to be divided.
Inflow and Outflow Control
I. Vascular inflow (i.e., hepatic artery and portal vein) and outflow (i.e., hepatic veins and IVC) control are obtained to minimize bleeding during parenchymal transection.
II. If a total lobectomy is to be performed, the hepatic artery and portal vein to that lobe can be dissected and divided. This can be achieved either through dissection of the extrahepatic right or left hepatic arteries or through transection of these pedicles within the liver substance after an opening is created in the liver parenchyma (i.e., hepatotomy) near the liver hilum. More selective inflow control can be obtained by dissecting branches of the hepatic artery or portal vein to specific segments.
III. Outflow control is achieved by dissecting and encircling the specific hepatic vein to the lobe or segment to be removed. Often, these veins are not divided until some portion of the parenchymal dissection has been performed, to allow for decompression of the lobe (Figs. 13-8 and 13-9).
IV. Total hepatic vascular exclusion is an alternative method by which vascular control is obtained. This technique is performed by clamping the IVC above and below the liver. The hepatic artery and the portal vein are controlled via Pringle’s maneuver (Fig. 13-10). Total vascular exclusion of the liver can be associated with significant hemodynamic changes. Therefore, this procedure is used only in select patients in whom more selective methods of inflow and outflow control are inadequate (e.g., patients with large tumors in close proximity to the major hepatic veins or IVC).
Parenchymal Transection
I. The hepatic parenchyma can be divided with a fracture technique, crushing the liver with clamps (Fig. 13-11). Newer devices, such as the ultrasonic dissector or water-jet dissector, are effective and may offer an additional degree of safety because they help to expose blood vessels before division.
II. Bleeding from the cut hepatic surface is controlled with electrocautery, an argon beam coagulator, or suture ligation. Pringle’s maneuver may be helpful in limiting bleeding from the hepatic remnant during hepatic transection.
ADDITIONAL OPERATIVE CONSIDERATIONS
I. Laparoscopic liver resections are being performed with increasing frequency as surgeons become more comfortable with this technique. Laparoscopic resection is typically limited to wedge resection of small peripheral lesions. Although major anatomic hepatectomy has been performed laparoscopically, this approach has not been widely adopted. In patients who undergo laparoscopic resection, decreased length of stay has been reported.
POSTOPERATIVE COURSE
I. Most patients who undergo uncomplicated major anatomic hepatectomy will be discharged from the hospital within 5 to 10 days. Intravenous or epidural analgesia is often necessary in the early postoperative period.
II. Complications
A. A bile leak from the cut surface of the liver, and development of a biloma (bile collection), can complicate postoperative recovery. This complication presents within days of surgery and may be heralded by the appearance of bile in the surgical drain, abdominal pain, or an elevated white blood cell count. Infection of a biloma can result in abscess formation.
B. Postoperative bleeding from the cut surface of the liver is a relatively rare complication of liver resection. Hemoglobin levels and hemodynamic parameters are monitored closely postoperatively.
C. Biliary stricture or obstruction is typically a later complication and presents with jaundice, elevations in total bilirubin, persistent pain in the right upper quadrant, and anorexia.
D. Hepatic function is also closely monitored in the postoperative period, because hepatic insufficiency can occur. This is most commonly observed in patients with compromised liver function who undergo major anatomic resection. In patients with a normal liver, serum ALT and AST levels peak 6 hours after surgery and remain elevated for approximately 3 days. After partial hepatectomy, levels of serum AST and ALT (transaminases) do not usually increase more than 10- to 15-fold; this increase is due to injury of hepatocytes during the procedure. In contrast to this expected mild transaminitis, elevation of coagulation parameters (e.g., INR) several days after hepatectomy is suggestive of hepatic insufficiency. Unfortunately, if severe hepatic insufficiency persists, no curative therapy is available other than liver transplantation.
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