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Radical Upper Abdominal Surgery: Liver, Diaphragm, and Spleen
The prognostic implications associated with the resection of all visible residual disease in patients with advanced-stage ovarian cancer have been clearly established in several retrospective and nonrandomized prospective studies. In 2013, Landrum and colleagues detailed the survival outcomes of patients with no visible residual disease treated with intraperitoneal chemotherapy, reporting a median overall survival of 110 months. Several other authors have also validated these findings.
Over the past decade, improved surgical techniques have resulted in higher rates of total macroscopic tumor clearance. The incorporation of what is commonly referred to as “radical upper abdominal surgery,” inclusive of diaphragm peritonectomy, splenectomy, and hepatic resections or ablative procedures, has been shown to increase the rates of complete tumor resection.
Advanced-stage ovarian cancer frequently involves upper abdominal structures, including the liver, diaphragm, and spleen. This disease distribution is not unexpected, given the physiologic distribution of peritoneal fluid, traveling in a clockwise manner along the right paracolic gutter to the right upper quadrant (RUQ) secondary to bowel peristalsis and diaphragmatic excursion with respiration. As many as 40% of patients with advanced-stage ovarian cancer have bulky tumor on the diaphragm. More specifically, diaphragmatic tumors are frequently identified in the region where the diaphragm peritoneum is reflected onto the posterior aspect of the right lobe of the liver, commonly adherent to and involving both the diaphragmatic and liver surfaces (Morison pouch, hepatorenal recess). This marks the most dependent portion of the abdominal cavity in the supine position.
Furthermore, preoperative radiographic imaging may indicate involvement of the liver parenchyma, gallbladder, and porta hepatis. These locations may also harbor recurrent, malignant lesions, necessitating resection at the time of secondary surgical cytoreduction in appropriately selected patients.
In addition to the RUQ, the left upper quadrant (LUQ) of the abdomen is reportedly involved with metastatic disease in up to 60% of patients with advanced-stage ovarian cancer. The anatomic relationships among the greater omentum, transverse colon, stomach, spleen, and left hemidiaphragm predispose patients to tumor involvement by contiguous extension. Less commonly, metastatic deposits may involve the stomach, splenic hilum, and left diaphragm independently.
Those critical of aggressive upper abdominal surgical resection have implied that upper abdominal disease burden is reflective of disease biology and negatively affects survival independently of surgical outcome. Conversely, published reports demonstrate that extensive upper abdominal resections required to achieve minimal residual disease are associated with extended long-term survival, and thus operative efforts should not be abbreviated because of metastatic disease present in this anatomic region.
Nevertheless, ovarian cancer metastases involving the liver, diaphragm, and spleen are frequently cited as impediments to achieving complete cytoreduction. Safe and effective operative and perioperative management of such disease requires that the surgeons responsible for managing disease in the upper quadrants of the abdomen be familiar with the regional anatomy and be proficient in both excisional and ablative techniques, allowing for complete surgical resection. The use of a multidisciplinary ovarian cancer surgical team, combined with developments in technology and instrumentation, has facilitated the inclusion of extensive upper abdominal procedures to achieve complete surgical cytoreduction in many patients. This chapter presents the relevant anatomy and surgical methods required for a proactive approach to cytoreduction in the upper quadrants, including the liver, diaphragm, and spleen.
Anatomic Considerations
Liver
The liver lies anatomically below the surface of the diaphragm in the RUQ of the abdominal cavity and is the largest gland in the female body, with a weight of approximately 1500 g. The gallbladder is adherent to the ventral surface of the liver and divides the right and left hemilivers, with the base of the liver oriented to the right and the contralateral apex to the left. The surface of the liver is red-brown, and the organ is enveloped by a layer of visceral peritoneum known as the Glisson capsule. The superior boundary of the liver corresponds to approximately the fifth rib; the inferior margin lies just below the costal margin.
The liver is secured by several ligamentous attachments including the round, falciform, triangular, and coronary ligaments ( Fig. 12.1 ). The round ligament, which is the remnant of the obliterated umbilical vein, enters the liver hilum at the leading edge of the falciform ligament, anchoring the liver to the anterior abdominal wall. The falciform ligament can then be followed to the left and right triangular ligaments, which extend anteriorly, where they are referred to as the coronary ligaments, anchoring the liver to the diaphragm’s surface. The right coronary ligament additionally extends to join the peritoneal reflection overlying the right kidney, providing additional retroperitoneal support. It is important to note that, in an analogous fashion to the avascular spaces of the pelvis, these ligaments can be divided in a bloodless manner to facilitate complete mobilization of the right and left hepatic lobes, allowing for surgical resection or ablation, and access to the commonly diseased diaphragm.
The liver is also secured centrally via the gastrohepatic and hepatoduodenal ligaments. The hepatoduodenal ligament is commonly referred to as the porta hepatis and houses the portal vein, hepatic artery, and common bile duct (portal triad). The hepatoduodenal ligament extends from the inferior aspect of the liver surface, to the left of the gallbladder, and attaches to the first and second portions of the duodenum. Immediately dorsal to the hepatoduodenal ligament is the epiploic foramen of Winslow, which can be accessed from the right side of the abdominal cavity, allowing access to the lesser sac. Isolation of the hepatoduodenal ligament facilitates compression of the portal triad, with control of vascular inflow to the liver, also known as the Pringle maneuver. The gastrohepatic ligament is also known as the lesser omentum and represents a double layer of peritoneum that extends from the liver to the lesser curvature of the stomach. The attachment of the lesser omentum to the liver is anterior to the caudate lobe and posterior to the left hemiliver.
Several important anatomic structures lie in close proximity to the liver, and understanding these anatomic relationships is important to the successful completion of a surgical procedure without unintended injury. The hepatic flexure of the transverse colon abuts the right border of the liver, whereas the duodenum is inferior to the liver and covered by the transverse colon and its associated mesentery. In addition, the right kidney and right adrenal gland lie in the right renal fossa, lateral and posterior to the second portion of the duodenum, and can be encountered with lateral dissection and mobilization of the liver in the anatomic region referred to as the Morison pouch.
Physiologically, the liver has several critical functions, including but not limited to storage; metabolism; synthesis of coagulation factors, complement, and proteins; secretion; and detoxification.
Liver Surface
As mentioned earlier, the liver surface is reddish-brown, smooth, and concave, conforming to the shape of the overlying diaphragm. The ligamentous attachments supporting the liver are in union with the Glisson capsule. The exception to the aforementioned relates to the posterior aspect of the liver, where the bare area lies within the boundaries of the coronary or triangular ligaments. The bare area is unique because the liver is in direct communication with the diaphragm’s surface and the inferior vena cava (IVC) and thus traditionally is spared from involvement by metastatic implant in patients with advanced-stage ovarian cancer.
Liver Segments
Grossly, the liver is divided into the right and left lobes by a plane connecting the gallbladder fossa to the center of the suprahepatic IVC (Cantlie line). The right lobe of the liver typically accounts for approximately 65% of the liver mass, with the left lobe accounting for the remainder. Commonly, the falciform ligament is interpreted as an anatomic demarcation between the right and left lobes of the liver. However, this is incorrect, because the falciform divides the left lateral segment from the left medial segment, with important implications in hepatic resections.
Significant advances in the understanding of liver surgical anatomy were ushered in by the French surgeon and anatomist Couinaud, who divided the liver into eight discrete segments ( Fig. 12.2 ). The segments are numbered in a clockwise fashion, beginning with segment I, or the caudate lobe. The caudate lobe represents the most dorsal portion of the liver and is in juxtaposition to the retrohepatic vena cava. The ligamentum venosum, or the fibrous remnant of the ductus venosus, is a continuation of the round ligament, and tumors along the ligamentum venosum often abut the anterior surface of the caudate lobe in the space between the left portal vein and the left hepatic vein. Segments II and III comprise the left lateral segments, whereas segment IV is the left medial segment. Uniquely, segment IV is further divided into segment IVA, cephalad and below the diaphragm, and segment IVB, caudal to segment IVA and adjacent to the gallbladder fossa. Thus, moving in a clockwise direction, the left lobe of the liver is composed of segments I through IV. Segments V, VI, VII, and VIII comprise the right lobe of the liver, with segments V and VIII referred to as the right anterior lobe and segments VI and VII as the right posterior lobe.
The functional hepatic anatomy is additionally demarcated by established fissures (scissura) defined by Bismuth in 1982, indicating the location of the three hepatic veins. The main fissure contains the middle hepatic vein and represents the anatomic delineation. The left hepatic vein drains the left lateral segments and lies within the left fissure. Last, the right hepatic vain courses long the right fissure and separates the right posterior lateral and right anterior lateral sections. Preservation of these veins is critical during segmental resections in order to avoid unintended congestion and necrosis of adjacent hepatic tissue.
Porta Hepatis
The porta hepatis contains three critical anatomic structures: the common bile duct, portal vein, and hepatic artery proper. The liver has a dual blood supply, receiving blood flow from two distinct sources: the proper hepatic artery and the portal vein. The hepatic artery is responsible for approximately 25% of the total blood supply to the liver, whereas the portal vein accounts for the remaining 75%. The common hepatic artery is a branch of the celiac trunk and courses anterior to the pancreas before giving off the gastroduodenal artery inferiorly, where it then becomes the hepatic artery proper, entering the hilum of the liver via the hepatoduodenal ligament. Within the hepatoduodenal ligament the hepatic artery proper is anterior to the portal vein and lies to the left of the common bile duct. The hepatic artery proper then branches to give rise to the right and left hepatic artery. The right hepatic artery commonly runs posterior to the bile duct before entering the right hemiliver. The cystic artery, supplying the gallbladder, arises from the right hepatic artery in variable locations within the Calot triangle.
There are several anatomic hepatic arterial variants, occurring in nearly 25% of patients, with which surgeons should be familiar before performing operative exploration in the region of the porta hepatis. Most commonly, there is a replacement or accessory right hepatic artery arising from the superior mesenteric artery, or an alternate left hepatic artery arising as a branch from the left gastric artery coursing through the hepatogastric ligament. Rarely seen is a complete replacement of the common hepatic artery arising from the superior mesenteric artery.
The portal vein accounts for approximately 75% of the hepatic blood supply. It is formed as the confluence of the splenic and superior mesenteric veins. The portal vein, in addition, receives nutrient-rich blood from the inferior mesenteric vein, which most commonly drains into the splenic vein. The main portal vein runs posterior to the proper hepatic artery and common bile duct before dividing into the right and left portal veins.
The left portal vein often has a longer extrahepatic course and branches sharply to the left before entering the left lobe of the liver at the umbilical fissure. The left portal vein supplies liver segments I, II, III, and IV. Conversely, the right portal vein is often larger in caliber and shorter, with anatomic variants including intraparenchymal branching. Analogous to the hepatic artery, there is significant anatomic variation of the portal venous anatomy, with 20% to 30% of individuals having portal vein trifurcation.
The flow of bile follows a sequential path from the biliary capillaries to the interlobar bile ducts, which merge to ultimately form the right and left hepatic ducts. The right and left hepatic ducts then come together to form the common hepatic duct, which accepts the cystic duct to become the common bile duct. The common bile duct is anterior within the porta hepatis and travels posterior to the duodenum, where it joins the pancreatic duct and empties into the second part of the duodenum via the ampulla of Vater.
Hepatic Veins
Hepatic venous drainage is accomplished via the right, middle, and left hepatic veins, which course through the liver and drain into the suprahepatic inferior vena cava (IVC). The right hepatic vein traditionally drains directly into the IVC, whereas the middle and left hepatic veins commonly merge to form a short trunk before entering the IVC. The right hepatic vein is responsible for the drainage of liver segments V, VI, VII, and VIII; the middle hepatic vein, segments IV, V, and VIII; and the left hepatic vein, segments II and III. The caudate lobe drains directly into the IVC via short perforating veins.
During the course of liver mobilization, catastrophic bleeding can be encountered secondary to inadvertent injury of these venous structures. Specifically, with mobilization of the right lobe of the liver, care must be taken to identify the right hepatic vein, protecting it from injury or laceration. This can also be seen with undue traction before adequate mobilization. Furthermore, 15% of patients may have an accessory right hepatic vein coursing ventral to the hepatocaval ligament. If concern exists, meticulous dissection and identification of these structures are required during surgical exploration.
Adjacent Organs at Risk: Stomach, Duodenum, Right Kidney, and Right Adrenal Gland
The liver and stomach are attached via the hepatogastric ligament. To allow for improved mobilization and exposure, facilitating dissection, oral or nasogastric tube decompression of the stomach can be performed. This can facilitate entry through the hepatogastric ligament, exposing the caudate lobe of the liver.
The duodenum is anatomically adjacent to the head and inferior border of the pancreas and may be encountered during mobilization of the right lobe of the liver and hepatic flexure of the colon and during a paraaortic lymphadenectomy approaching the level of the right renal vein. Thus the surgeon should be aware of the duodenum’s anatomic location and considerations. The duodenum is approximately 25 cm in length and has four parts. The first part of the duodenum is a continuation of the pylorus and lies within the intraperitoneal compartment. It is attached to the liver via the gastroduodenal ligament. The components of the portal triad are located immediately posterior to the first part of the duodenum. The second part of the duodenum is retroperitoneal and travels parallel to the IVC, anterior to the right kidney, and right renal vessels. It is in close proximity to the right inferior lobe of the liver. The third part of the duodenum travels horizontally across the midline, coursing beneath the superior mesenteric artery. The final, fourth part of the duodenum then travels back into the peritoneal cavity, joining the proximal jejunum, where it is suspended by the ligament of Treitz.
The right kidney is in close anatomic approximation with the hepatic flexure of the colon, the second portion of the duodenum, the right lobe of the liver, and the small bowel. The right adrenal gland rests on the superior border of the right kidney. The right kidney is enveloped in perinephric fat and is covered with a fibroareolar layer termed Gerota fascia that, in addition, encompasses the adrenal gland. The Morison pouch is the peritoneal reflection separating the kidney from the right lobe of the liver and is a common location for metastatic ovarian cancer deposits.
The right renal artery courses inferiorly and travels posterior to the IVC and the right renal vein. The right adrenal gland, typically measuring 4 cm in length and 2 cm in width, is triangular and retroperitoneal and rests above the right kidney. Along with the kidney, it is contained within Gerota fascia. The adrenal glands are among the most vascularized organs in the body, which can result in unanticipated bleeding if they are traumatized during mobilization of the posterior right lobe of the liver. The right adrenal vein, which drains directly into the IVC, is also at risk of injury during hepatic mobilization. The right adrenal tissue is a bright yellow-orange color, helping distinguish it from neighboring adipose tissue.
Diaphragm
Anatomically, the diaphragm is a large dome-shaped structure, composed of muscle and fibrous tissue, that separates the thoracic from the abdominal cavities. It plays a principal role in respiration. The thoracic aspect of the diaphragm is in contact with the lung pleura. The contralateral side is lined by the abdominal peritoneum anteriorly and laterally. The medial abdominal diaphragmatic surface is retroperitoneal and corresponds to the bare area previously discussed. The right posterior lateral aspect of the abdominal diaphragm is in contact with the right kidney and represents the caudal boundary of Morison pouch. The left posterior lateral aspect is in contact with the spleen via the phrenorenal ligament, which must be transected during splenectomy.
Muscular Components
The diaphragm is composed of skeletal muscle and originates from three distinct regions. The sternal, costal, and lumbar components of the diaphragm arise from the xiphoid process, lower six ribs, and diaphragm crura, respectively. The posterior boundary of the diaphragm is composed of the lateral and medial arcuate ligaments, which circumscribe the proximal portions of the quadratus lumborum and psoas muscles, respectively. All the muscular fibers insert into the central tendon of the diaphragm, which is an aponeurosis in the center of the diaphragm ( Fig. 12.3 ).
Apertures and Visceral Relations
There are three principal diaphragmatic apertures. The most inferior is the aortic hiatus, which is found at the level of the 12th thoracic vertebra. It lies between the right and left crura of the diaphragm and contains the aorta, azygos vein, and thoracic duct. The esophageal hiatus is at the level of the 10th thoracic vertebral body and is located to the left of the central tendon enveloped by the right crus of the diaphragm. The esophageal hiatus contains the esophagus as well as the anterior and posterior vagal trunks. Lastly, the caval opening is at the level of the eighth thoracic vertebra, passing through the central tendon of the diaphragm. It contains the IVC and branches of the right phrenic nerve. In rare cases, the right hepatic vein may pass through the caval aperture before joining the IVC.
Innervation and Vascular Supply
The vascular supply to the diaphragm is principally composed of the phrenic, pericardiophrenic, and musculophrenic arteries. The phrenic artery is the most cephalad branch of the abdominal aorta, whereas the musculophrenic and pericardiophrenic are branches from the internal thoracic artery. The venous drainage is via the brachiocephalic vein and azygos vein. The diaphragm is primarily innervated by the phrenic nerve, which is formed from cervical nerve roots 3, 4, and 5 (C3, C4, and C5).
Ligaments of the Liver and the Bare Area
As reviewed in the discussion of anatomic considerations for the liver, access to the diaphragm for surgical resection of metastatic implants will require complete liver mobilization. This is accomplished by taking advantage of the avascular planes represented by the falciform, coronary, and triangular ligaments. Furthermore, the bare area is retroperitoneal and spared from intraperitoneal tumor spread, allowing it to be used as an anatomic “boundary” for the posterior dissection. The only exception to this rule is in patients with prior liver mobilization. Mobilization of the liver, by careful dissection along the ligamentous attachments, facilitates maximal exposure of the right diaphragm and hepatorenal recess.
Spleen
Anatomically, the spleen can be found between the greater curvature of the stomach and the left diaphragm. The hilum of the spleen frequently abuts the tail of the pancreas, whereas the inferior border of the spleen is adjacent to the splenic flexure of the colon ( Fig. 12.4 ). The spleen is held in place by several ligamentous attachments including the gastrosplenic, splenocolic, splenorenal (also known as lienorenal), and splenophrenic ligaments. The anterior surface of the spleen lies posterior to the stomach and is frequently in contact with the tail of the pancreas.
The blood supply to the spleen comes from the splenic artery, which is a branch of the celiac trunk. The splenic artery runs along the superior border of the pancreas, entering the spleen at the hilum. During its course, the splenic artery gives off several collateral branches that supply the pancreas including the greater pancreatic artery, in addition to the short gastric arteries and left gastroepiploic artery, which perfuse the greater curvature of the stomach and greater omentum. Analogous to the variations seen in hepatic blood flow, there are several anatomic variations in splenic arterial anatomy.
Pancreas
Given the anatomic proximity of the pancreas to the splenic hilum, a thorough understanding of pancreatic anatomy is critical for operative exploration of the LUQ. The pancreas is a retroperitoneal organ that is yellow and lies anterior to the abdominal aorta and vena cava at the level of the first and second lumbar vertebral bodies. At the time of operative exploration, the peritoneal reflection overlying the pancreas can be easily appreciated at the base of the lesser sac.
The pancreas is composed of a head, uncinate process, and pancreatic neck, body, and tail. The head of the pancreas is intimately related to the second portion of the duodenum, where the pancreatic head rests in the concavity of the most proximal portion of the small bowel. The head of the pancreas lies anterior to the common bile duct, IVC, aorta, right renal artery, and both renal veins and is covered anteriorly by the transverse colon mesentery. The body of the pancreas is superior to and adjacent to the junction between the duodenum and jejunum and is separated from the body of the stomach anteriorly by the lesser sac. There are several important anatomic structures posterior to the body of the pancreas including the splenic vein, inferior mesenteric vein, and aorta, as well as the left kidney and renal vessels.
The pancreatic tail extends to the left colic flexure and in 40% of patients is within 1 cm of the splenic hilum. Consideration of this relationship is important at the time of splenectomy in order to avoid unrecognized injury to the tail of the pancreas. It is important to note that the pancreatic duct of Wirsung courses through the pancreas, from the tail toward the neck, where it joins the common bile duct, emptying into the duodenum via the ampulla of Vater.
The arterial blood supply to the pancreas arises from branches off of the splenic artery, as well as the left gastroepiploic artery and the pancreaticoduodenal artery. The venous drainage is principally into the splenic vein and superior mesenteric vein.
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