Understanding the abdominal and pelvic visceral anatomy is critical to understanding and predicting the pathways by which disease may spread throughout the abdomen and pelvis. The ligamentous attachments that interconnect the intra-abdominal organs are critically important as these are common conduits for the spread of disease. Moreover, the organs and the peritoneal ligaments that support them form the boundaries of the peritoneal cavity, and together, they guide the flow of peritoneal fluid throughout the abdomen and pelvis. Neoplastic and inflammatory processes that extend into the peritoneal cavity may spread through the ascitic fluid that flows through these peritoneal spaces.
Disease may spread through the abdomen and pelvis by a variety of mechanisms. For example, intra-abdominal malignancies may metastasize through hematologic routes, and tumors may spread by directly invading adjacent tissues and organs or via the lymphatic system. When tumors break through the visceral peritoneum, they may also spread via intraperitoneal seeding. While hematologic spread of disease is beyond the scope of this chapter, direct invasion, lymphatic extension, and intraperitoneal seeding will be discussed relative to the anatomy that guides these pathways for the spread of disease in the abdomen and pelvis [1].
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Direct invasion and lymphatic extension occur through the peritoneal ligaments and mesenteries that interconnect the abdominal viscera with other organs in the abdomen and pelvis, the retroperitoneum, and the body wall. Moreover, these structures guide the flow of peritoneal fluid through the abdomen and pelvis, thereby dictating the routes of spread through intraperitoneal seeding. In short, understanding these pathways for the spread of disease ties closely to a clear understanding of a ligamentous anatomy of the abdomen and pelvis.
The gastrohepatic and hepatoduodenal ligaments form an important pathway of disease from the lesser curvature of the stomach to the porta hepatis and retroperitoneum. The gastrohepatic ligament extends from the lesser curvature of the stomach to the porta hepatis, inserting into the fissure for the ligamentum venosum. Containing the left gastric artery, the left gastric vein or coronary vein, and associated lymphatics, the gastrohepatic ligament may be recognized on cross-sectional imaging as the fatty plane connecting the lesser curvature of the stomach to the left lobe of the liver and containing these vessels (Fig. 6.1). Nodes in the gastrohepatic ligament are typically 8 mm or less in diameter, somewhat smaller than elsewhere in the abdomen [2]. Care must be taken to avoid misidentifying unopacified loops of bowel, the pancreatic neck, or the papillary process of the caudate lobe as enlarged nodes in the gastrohepatic ligament [3, 4].
An important highway of disease is provided in the left upper abdomen by the gastrosplenic and splenorenal ligaments, connecting the gastric greater curvature to the splenic hilum and the retroperitoneum, respectively (Fig. 6.4). The gastrosplenic ligament is a rather thin delicate structure that connects the superior third of the greater curvature of the stomach to the splenic hilum. This ligament contains the left gastroepiploic and short gastric vessels and their associated lymphatics. The gastrosplenic ligament can direct diseases arising in the stomach to the splenic hilum, and both neoplastic and inflammatory disease may invade the spleen via this pathway.
As the gastrohepatic and hepatoduodenal ligaments in the right abdomen and the gastrosplenic and splenorenal ligaments in the left abdomen form important pathways of disease from the upper abdominal viscera to the retroperitoneum, the gastrocolic ligament and transverse mesocolon form a similar pathway in the mid-abdomen. The gastrocolic ligament (greater omentum) connects the inferior two thirds of the greater curvature of the stomach to the transverse colon (Fig. 6.6). On the left, the gastrocolic ligament is continuous with the gastrosplenic ligament, and on the right, it ends at the gastroduodenal junction near the hepatoduodenal ligament. Embryologically, the gastrosplenic ligament gives rise to the gastrocolic ligament and the transverse mesocolon in the adult, with fusion of the anterior and posterior leaves of the embryonic gastrosplenic ligament. In consequence, the gastrocolic ligament has a potential space within it that can fill with fluid when tense ascites in the lesser sac dissects open this potential space. This can result in a cyst-like appearance within the gastrocolic ligament/greater omentum.
The gastrocolic ligament contains the gastroepiploic vessels and associated lymphatics which can help identify the ligament as the fatty plane connecting the stomach to the transverse colon. Both benign and malignant diseases from the inferior two thirds of the greater curvature of the stomach may spread to the transverse colon via this pathway, and vice versa (Fig. 6.7). The transverse mesocolon completes the pathway from the stomach to the retroperitoneum in the mid-abdomen; disease involving the stomach and transverse colon are connected via the gastrocolic ligament, and disease involving the transverse colon and pancreas/retroperitoneum are connected by the transverse mesocolon. In addition, the greater omentum continues inferior to the transverse colon as a fatty veil that forms an important nidus for carcinomatosis, as commonly occurs with ovarian, gastric, colon, and pancreatic cancers [10, 11]. Sometimes, gastroepiploic collaterals may be recognized in the gastrocolic ligament which should raise concern about the possibility of splenic venous compromise as what commonly occurs in pancreatic carcinoma.
A thorough understanding of the peritoneal ligaments and mesenteries as well as the peritoneal spaces that they define can inform the pathways by which inflammatory and neoplastic diseases may spread throughout the abdomen and pelvis. 2ff7e9595c
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