The paraaortic lymph node is lymph tissue located near the aorta, right in front of several lumbar vertebrae. Another term for the paraaortic lymph node is periaortic lymph node. As part of the lymphatic system, a paraaortic lymph node helps drain dead cells and immune system-neutralized foreign bodies. In particular, a paraaortic lymph node helps drain the organs in the pelvis and the lower part of the digestive system.

A peri-aortic lymph node can be classified based on its location. The preaortic group is located in front of the aorta. Each preaortic lymph node drains sections of the gastrointestinal tract found in the abdomen until the mid-rectum. The preaortic group can further be divided into the superior mesenteric, celiac, and inferior mesenteric lymph nodes, according to their arrangement around the superior mesenteric, celiac, and inferior mesenteric arteries. These arteries are the major blood supplier of the digestive system.

The set of periaortic lymph nodes located near the third and fourth lumbar vertebral bodies, just behind the aorta, is called the retroaortic or postaortic group. These retroaortic lymph nodes receive drainage from the left lateral aortic glands and the right lateral aortic glands. The sets of glands are collectively termed the lateral group.

In males, the left and right lateral aortic glands drain the testes; in females, they drain the ovaries, uterus, and Fallopian tubes. They also drain the kidneys, adrenals, lateral abdominal muscles, and common iliac glands. The right lateral aortic glands are located anterior to the inferior vena cava, around the area where the renal vein terminates. Left lateral aortic glands are arranged in a chain structure on the left of the abdominal aorta.

Any infection or pathology in the parts of the gastrointestinal tract located in the abdomen and pelvic organs drain into the paraaortic lymph node. When there is a suspicion of cancer or when doctors want to know how widely cancer has spread into the abdominal and pelvic cavities, a biopsy of the paraaortic lymph node is performed. Usually, a surgeon performs a procedure called mediastinoscopy, whereby a lighted camera is inserted within the chest in order to visualize the paraaortic lymph node. Instruments used for biopsy are then inserted into the chest, together with the mediastinoscope, in order to get a sample of the paraaortic lymph node. Determining which lymph nodes have cancer is important because it allows staging of the disease and it lets the doctor know about a patient’s prognosis or outcome.

The dissection or removal of a para-aortic lymph node is also important in the surgical treatment of cancer. Para-aortic node dissection usually involves the lateral group, which has approximately 20 nodes on each side. Typically, the surgeon starts dissecting at the region where the aorta bifurcates or branches off, and removes the lymph node chains up to the renal veins or the superior mesenteric artery. The peri-aortic lymph nodes are in close proximity to the aorta, which is the largest blood vessel of the body. Therefore, great care is undertaken during lymph node biopsy and dissection.