The veins of the human body are thousands of tiny tunnel-like vessels that carry blood around a circuit in the body, to feed its cells, deliver oxygen, and carry out waste and impurities, and to then be cleaned and oxygenated through the heart and lungs. The veins are different sizes and are connected to various muscles, organs, and other tissue, and each have a different function.
The inferior vena cava carries blood back to the heart from the lower body. It is also known as the posterior vena cava, although inferior vena cava is more commonly used. This large vein functions to carry de-oxygenated blood, which is when oxygen in the blood has been fed and then removed by certain tissues. This de-oxygenated blood is darker than other blood.
To perform its function, the inferior vena cava starts at the legs and runs the blood upward, behind or posterior to the abdomen or stomach, and then emptying it into the right atrium of the heart. This atrium is located in the back, lower right part of the heart. As it runs past the lower torso of the body, the inferior vena cava also runs parallel to the right vertebra part of the spinal column.
At the head of the inferior vena cava or where it begins, there are two large leg veins that meet. These are the iliac veins and they merge at the fifth lumbar vertebra, which is in the small of the back. It is here that the inferior vena cava takes over to transport this de-oxygenated blood back to the heart.
Health Problems With the Inferior Vena Cava:
It is rare for the inferior vena cava to rupture as it has a very low pressure. However, it is not so rare for the vein to become compressed because of where it is located and how it functions. An enlarged aorta and conditions such as colorectal cancer, ovarian cancer, and renal cell carcinoma are typical reasons for the inferior vena cava to become compressed. The uterus can also cause pressure because of where it is located, and unconscious pregnant women need to be turned to their left side consistently to avoid this compression and allow the healthy flow of blood to return. It is rare but straining to defecate can also cause a restriction in blood flow through the inferior vena cava and in turn, lead to syncope or fainting.
Because of its size and function, it is possible for exsanguinations (blood loss) to occur and quite rapidly, if there has been serious trauma to the inferior vena cava. This is often due to accident or injury. Occlusion is also life-threatening and this may be associated with liver transplants, deep vein thrombosis, and instrumentation including catheters placed in the femoral vein. These too are rare and doctors and surgeons are typically alert to risk factors for the inferior vena cava during surgery or other serious illnesses and conditions that may occur.