The cisterna chyli is a major reservoir within the body’s lymphatic system, acting as a central collection point for fluid before it is returned to the bloodstream. Its name, derived from Latin, translates to “chyle cistern,” which hints at its specialized function in handling digestive products. This dilated sac is situated deep within the abdomen, serving a crucial role in maintaining fluid balance and transporting dietary fats. Understanding the cisterna chyli requires examining its precise location and the unique fluid it collects.
Anatomical Location and Structure
This structure is a saccular dilation of the lymphatic channels, typically located in the retroperitoneal space behind the lining of the abdominal cavity. The cisterna chyli is most commonly positioned in front of the L1 and L2 vertebral levels. It usually lies slightly to the right of the abdominal aorta, nestled behind the right crus of the diaphragm.
Physically, the cisterna chyli is an elongated, sac-like structure that marks the lower end of the thoracic duct, the largest lymphatic vessel in the body. Its size and shape can be quite variable, sometimes appearing as a thin tube, a bulbous sac, or a plexus of vessels. It commonly extends between 5 to 7 centimeters in length, acting as a confluence point for several major lymphatic trunks from the lower body.
Primary Role in Lymphatic Drainage
The function of the cisterna chyli is to act as a receiving tank for lymph fluid draining from the lower half of the body. It collects fluid from the intestinal trunk, which drains the gastrointestinal tract, and the two lumbar lymphatic trunks, which drain the lower extremities, pelvis, and abdominal wall. This convergence makes it the most common drainage trunk for a large portion of the body’s lymphatics.
A unique substance collected here is chyle, a milky fluid that gives the structure its name. Chyle is lymph enriched with emulsified fats and fat-soluble vitamins absorbed from the small intestine following a meal. The cisterna chyli is instrumental in the transport of dietary lipid products, ensuring these absorbed fats are delivered to the circulatory system. The cisterna chyli is recognized as the origin point of the thoracic duct, which ascends through the diaphragm to carry this collected fluid toward the neck, where it re-enters the bloodstream.
Clinical Significance
When the cisterna chyli’s drainage pathway is blocked or damaged, specific health conditions can arise. A major consequence of leakage is chylous ascites, a rare condition characterized by the accumulation of fat-rich lymph within the abdominal cavity. This leakage can occur due to traumatic injury, surgical damage to the retroperitoneal lymphatics, or obstruction by tumors or other masses.
Obstruction or damage to the cisterna chyli or its tributaries contributes to lymphedema, a condition of swelling, particularly in the lower extremities, due to impaired fluid drainage. In medical imaging, the structure serves as a landmark for diagnostic procedures like lymphangiography, which helps pinpoint the source of a chyle leak or obstruction. Due to its location adjacent to the abdominal aorta and major lymph node groups, the cisterna chyli is of interest in surgical oncology during procedures for abdominal malignancies.