The inferior vena cava is a large heart vein that brings deoxygenated blood from parts of the lower body, including the legs, abdomen and pelvis, to the heart to be oxygenated. From the heart, this blood is then pumped back through the body to deliver oxygen to the body cells. Also known as the posterior vena cava, this large vein empties into the right atrium of the heart, connecting on the lower, rear side of the atrium. Its complementary vein, the superior vena cava, which delivers blood from the upper part of the body, also empties into the right atrium but does so through the top part of the chamber.
Numerous veins from the lower part of the body empty into the inferior vena cava, including the iliac, testicilar, hepatic, renal and suprarenal veins. These smaller veins serve specific areas of the lower body, then join together as the blood continues its journey back through the heart. In turn, the iliac vein and other tributaries are fed by even smaller veins, and still smaller veins feed those veins, ensuring that deoxygenated blood from every cell of the body is circulated back through the heart.
Some problems that can develop within the inferior vena cava include compression and thrombosis. Compression is a more common problem with this vein and can occur because of different factors. In some cases, the vein is compressed by the aorta, and, more commonly, by the growing uterus during the course of pregnancy. For this reason, pregnant women are advised to sleep on their left side in order to reduce the possibility of compressing this large vein, which can lead to dizziness and fainting. For the same reasons, unconscious pregnant women should also be turned onto their left sides while awaiting treatment.
Thrombosis of the inferior vena cava is relatively rare and occurs because of various clotting disorders that cause deep vein thrombosis or lead to an overall higher risk of blood clots within the veins. A possible treatment for thrombosis is the placement of a filter, which breaks up developing clots in the vein. Unfortunately, the filter sometimes can cause an obstruction in the vein, which leads to other complications. Additional causes of obstruction, other than compression, include tumors such as renal cell carcinoma. Blockages or other obstructions are also referred to as inferior vena cava syndrome.