Lymphatics of abdomen and pelvis
The lymphatics of the abdomen and pelvis represent a network of vessels and nodes that collect and transport lymph. One important role of the lymphatic system includes the removal of various substances (cellular waste, water, proteins) from the interstitial fluid. It is also involved in fat absorption from the gut and protection against pathogens.
Lymph is filtered through lymph nodes which house immune cells that continuously sample it, ready to mount an immune response. It is a similar situation to airport security checks - unavoidable by everyone due to their strategic positioning, uncomfortable for delinquents, and constantly checking every single person.
|Abdominal wall||Superficial system: to axillary, parasternal and superficial inguinal lymph nodes
Deep system: to lumbar lymph nodes
|Retroperitoneum||To lumbar lymph nodes|
|Gastrointestinal tract||To superior and inferior mesenteric lymph nodes|
|Adrenal glands||To lumbar lymph nodes|
|Urinary system organs||To lumbar and iliac lymph nodes|
|Reproductive organs||To lumbar, iliac and inguinal lymph nodes|
|Abdomen and pelvis||To thoracic duct|
This article will focus on the lymphatics of the abdomen and pelvis, explaining the drainage of the organs found here and the location of their associated lymph nodes.
- Abdomen and pelvis drainage
- Abdominal wall
- Small and large intestines
- Liver and gallbladder
- Urinary bladder
- Reproductive organs
- Clinical information
Abdomen and pelvis drainage
Lymph from abdominal organs reaches the lumbar (right, left) and intestinal lymphatic trunks bypassing via relay lymph nodes surrounding the great abdominal vessels. These trunks unite at the cisterna chyli, forming the thoracic (left lymphatic) duct. This major lymphatic vessel empties into the venous circulatory system at the junction between the left subclavian and internal jugular veins. Lymphatic drainage of the pelvis closely resembles the abdomen. Lymph from the pelvic viscera reaches the common iliac lymph nodes bypassing via relay nodes (external iliac, internal iliac, sacral) located in the vicinity of the great pelvic blood vessels. The lumbar lymphatic trunks subsequently collect the lymph from the common iliac lymph nodes.
The anterior abdominal wall consists of two lymphatic drainage systems:
- a superficial system which drains the skin and subcutis, and
- a deep system which primarily drains the musculature and bones.
The superficial system is divided into two territories by a horizontal, imaginary plane passing through the umbilicus (transumbilical plane). The majority of the lymph in the supraumbilical territory is drained by lymphatic vessels which empty into the anterior, or pectoral axillary lymph nodes, while a small portion ends up into the parasternal lymph nodes. In turn, lymphatic vessels found in the infraumbilical territory follow the superficial epigastric vessels and drain into the superficial inguinal lymph nodes.
In contrast, the lymphatic vessels of the deep system follow the course of some slightly deeper vessels, and follow three primary pathways:
- The superior epigastric pathway which follows the superior epigastric artery and drains into the parasternal nodes.
- The inferior epigastric pathway which follows the inferior epigastric artery and drains into the external iliac nodes.
- The intercostal pathway which follows in the inferior intercostal and subcostal arteries to the posterior mediastinal nodes.
The lymphatic drainage of the posterior abdominal wall follows a similar pattern, with both superficial and deep lymphatic networks draining this region. Superficial drainage is achieved in both the lumbar and iliac regions via lymphatic vessels which follow the superficial circumflex blood vessels. The deeper lymphatic vessels follow two primary drainage pathways:
The peritoneum is a serous membrane that lines the abdominal wall and the majority of internal organs.
Posterior to it one can find the retroperitoneal space, which houses the anatomical structures not lined by the visceral peritoneum (e.g. the kidneys, ascending/descending colon etc.). How is lymph drained from the retroperitoneum? The retroperitoneal, or lumbar lymph nodes are commonly located around the abdominal aorta and inferior vena cava, forming three distinct groups: left lumbar (para-aortic), right lumbar (para-caval), and intermediate lymph nodes. The latter group is situated between the two great abdominal vessels.
The left lumbar, or para-aortic, lymph nodes are situated in the vicinity of the abdominal aorta. They are divided into several subgroups and drain parts of the gastrointestinal tract, the internal organs located on the left side of the abdomen, the left testis/ovary, as well as some deep tissues of the posterior abdominal wall. In contrast, the right lumbar, or para-caval, lymph nodes surround the inferior vena cava. They also consist of several sub-groups and drain parts of the gastrointestinal tract and other structures located mainly on the right-hand side of the abdomen(e.g. right kidney and adrenal gland), as well as the right gonad. It’s quite logical, right? If you remember that the aorta is located slightly to the left within the abdomen, while the inferior vena cava is more to the right, then learning becomes logical without the need of brute memorization.
|Left lumbar (paraaortic)||
Location: adjacent to abdominal aorta
Groups: preaortic (celiac, superior mesenteric, inferior mesenteric), lateral aortic, retroaortic
Drainage: gastrointestinal tract, left-sided abdominal structures, left testis/ovary
|Right lumbar (paracaval)||
Location: adjacent to inferior vena cava
Groups: precaval, lateral caval, retrocaval
Drainage: gastrointestinal tract, right-sided abdominal structures, right testis/ovary
|Intermediate lumbar||Location: between abdominal aorta and inferior vena cava|
As you know, the peritoneum surrounds several internal organs, so let’s take them one at a time and to explore their lymphatic drainage. The stomach is an organ of the digestive system consisting of four parts and two curvatures, all of which are closely related to its lymphatic drainage. The lymph vessels draining this entire organ travel along the lesser and greater curvatures of the stomach, ultimately emptying in the gastric and gastroomental lymph nodes. The pyloric part is drained by the pyloric lymph nodes, which subsequently empty into the celiac lymph nodes. The latter are located around the celiac trunk.
Small and large intestines
Moving further along the digestive system, we come across the small and large intestines. The small intestine is anchored to the abdominal by the mesentery, a key structure involved in its lymphatics. The mesentery contains an extensive lymphatic network of approximately 150 lymph nodes which are arranged into three stations:
- the juxta-intestinal nodes (found along peripheral arterial arcades)
- the intermediate mesenteric nodes (along the jejunal and ileal arteries), and
- (central) superior mesenteric nodes (along the length of the superior mesenteric artery).
Lymph from the lacteal passes sequentially through these group of lymph nodes before finally ending up in the superior mesenteric lymph nodes. Lymph from the proximal duodenum flows through superior pancreaticoduodenal, pyloric, hepatic lymph nodes which drains to the celiac lymph nodes. The terminal ileum is also an exception because lymph follows the ileocolic artery towards the ileocolic lymph nodes. The lacteals of the small intestine are important for the transportation of fats and fat soluble vitamins.
The large intestine represents the last part of the gastrointestinal system and consists of several parts, each one with its own lymphatic drainage.
|Cecum||Cecal lymph nodes -> Ileocolic lymph nodes -> Superior mesenteric lymph nodes|
|Appendix||Appendicular lymph nodes -> superior mesenteric lymph nodes|
Inferior part: ileocolic and paracolic lymph nodes;
Superior part: right colic nodes -> superior mesenteric lymph nodes and/or right lumbar nodes
|Transverse colon||Middle colic lymph nodes -> superior mesenteric lymph nodes|
|Descending colon||Right nodes -> inferior mesenteric lymph nodes|
|Sigmoid colon||Sigmoid lymph nodes -> inferior mesenteric lymph nodes|
Superior part: superior rectal & pararectal lymph nodes -> inferior mesenteric lymph nodes
Inferior part: pararectal lymph nodes -> sacral and internal iliac lymph nodes
Above pectinate line: internal iliac lymph nodes
Below pectinate line: superficial inguinal lymph nodes
In the end, the celiac and mesenteric lymph nodes, which drain the majority of the gastrointestinal tract, as you can see, flow into the intestinal lymphatic trunk.
Liver and gallbladder
The liver and gallbladder are two accessory organs of the digestive system responsible for many important functions, for example, detoxification and fat emulsification. The lymphatics of the liver are separated into superficial and deep systems:
- The superficial lymphatic network is located within the superficial fibrous capsule of the liver (Glisson’s capsule). Lymph vessels from the anterior/convex aspect of the liver follow the portal triads, draining into the hepatic lymph nodes located at the porta hepatis. Lymph continues into the celiac lymph nodes, which subsequently drain into the cisterna chyli. In contrast, the superficial lymphatic vessels of the posterior aspect of the liver drain mainly into the phrenic (diaphragmatic) lymph nodes and posterior mediastinal lymph nodes. After passing through several relay stations along the way, lymph from these regions ultimately reaches the right lymphatic and thoracic ducts.
- The deep lymphatics of the liver follow the connective tissue around the hepatic veins all the way to the inferior vena cava, where they flow in the posterior mediastinal lymph nodes. These also empty in the right lymphatic and thoracic ducts.
The lymphatics of the gallbladder and biliary system drain to three destinations, these being the cystic and hepatic lymph nodes, as well as the lymph node of the omental foramen. From these locations, the lymph continues towards the celiac lymph nodes.
The pancreas is another accessory organ of the digestive system that also plays a crucial role in the endocrine system. It is both an exocrine gland that facilitates digestion and an endocrine gland that releases mainly insulin and glucagon. The tail of the pancreas is drained by lymphatic vessels that empty into the splenic lymph nodes located along the splenic artery. Lymph drained from the body of the pancreas is largely emptied into the superior and inferior pancreatic lymph nodes, while vessels draining the head primarily empty into pancreaticoduodenal lymph nodes. Lymph from these sets of lymph nodes is subsequently transported to the superior mesenteric or celiac lymph nodes.
The spleen has a very similar lymphatic drainage to the tail of the pancreas. Lymphatic vessels travel along the splenic artery and empty into the splenic lymph nodes. As you know, these flow into the celiac lymph nodes.
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The kidneys are two retroperitoneal organs responsible for blood filtration and urine production. Their lymphatic drainage follows the course of the renal veins and ends in the para-caval (right lumbar) and para-aortic (left lumbar) lymph nodes.
Sitting on top of the kidneys are the adrenal glands, two endocrine organs that can induce the ‘flight-or-fight’ response when facing danger. Their lymphatic vessels drain in the ipsilateral lumbar lymph nodes.
The urine produced in the kidneys travels via the ureters to the urinary bladder, where it is finally stored until urination. The ureters descend from the renal pelvis of the kidney, transporting urine to the urinary bladder. When describing the lymphatics of the ureters, these can be divided into three parts; the superior third is drained by the lumbar lymph nodes, the middle third by the common iliac lymph nodes, while the inferior third by the internal and external iliac nodes.
Lymph from the urinary bladder reaches the internal and external iliac lymph nodes. The former drains mostly the neck and fundus of the urinary bladder. The urinary bladder is continued by the urethra, a tubular structure that transports urine to the external environment. The female urethra drains mostly to the internal iliac lymph node. However, the longer male urethra flows in two directions: the proximal part to the internal iliac lymph nodes and the distal part to the inguinal lymph nodes.
Reproduction is essential for the survival of the human species because it involves the generation of new offspring and passing on our genes to future generations. The male reproductive system consists of several anatomical parts, some of which are internal while others are external. They are outlined in the following table, together with their lymphatic drainage.
|Testes & Epididymis||
Right testis: right lumbar (paracaval) lymph nodes
Left testis: left lumbar (paraaortic) lymph nodes
|Ductus deferens, Ejaculatory ducts, Seminal vesicles, Bulbourethral glands, Prostate gland||Internal and external iliac lymph nodes|
Skin: superficial inguinal lymph nodes
Glans penis & corpora cavernosa: superficial inguinal, deep inguinal and external iliac lymph nodes
|Scrotum||Superficial inguinal lymph nodes|
The female reproductive system has similar functions to its male counterpart, however it is more complex due to the necessity of accommodating a developing fetus. It is also associated with an intricate hormonal menstrual cycle that induces significant physiological and local anatomical changes within the body. The lymphatics of each specific part are outlined below:
|Ovaries||Right and left lumbar lymph nodes|
|Fallopian tubes||Right/Left lumbar and internal iliac lymph nodes|
Fundus: lumbar and superficial inguinal lymph nodes
Body: external iliac lymph nodes
Cervix: internal iliac and sacral lymph nodes
Superior part: internal and external iliac lymph nodes
Middle part: internal iliac lymph nodes
Inferior part: sacral and common iliac lymph nodes
External orifice: superficial inguinal lymph nodes
|Vulva (external female genitalia)||Superficial and deep inguinal lymph nodes|
Normal and healthy lymph nodes have a diameter less than 1 cm. Although they may be larger in adolescents and children, a lymph node greater than 1 cm in diameter is considered lymphadenopathy. This condition can be localized, involving only a few lymph nodes in a respective area, or generalized, which is a frequent sign of a systemic disease.
When discovering a local lymphadenopathy it is important to take a thorough patient history, focusing on constitutional symptoms like fever, weight loss, and night sweats which often indicate a serious pathology. Then, the location, size, shape, consistency, mobility, tenderness, regularity, skin changes, and elevation of the lymph node should be examined. Generally speaking, a painless, fixed, irregular, and hard nodule raises the suspicion of malignancy. The main abdominopelvic lymph nodes that can be palpated are the inguinal ones, but in case of abdominal or pelvic carcinomas, a left supraclavicular lymph node enlargement (Virchow-Troisier sign) is possible.