What is the inferior vena cava?

The inferior vena cava, also referred to as the posterior vena cava, is the largest vein in the human body. It is responsible for carrying deoxygenated blood from the lower body (lower limbs and all organs located below the diaphragm) to the heart. Located mainly in the abdominal cavity (only a small portion starts in the chest cavity), it lies posterior to the abdominal cavity and runs vertically along the right side of the spine. It enters the right atrium at the lower right, back side of the heart. 

The inferior vena cava is approximately 22 cm in length (18 of which run through the abdomen) and about 30mm in diameter. It is formed by the confluence of two large veins: the left and right common iliac veins, each of which are formed by the fusion of internal iliac veins and external iliac veins. The iliac veins are responsible for collecting blood from the lower limbs, pelvis, external genitalia, and abdominal wall. Deoxygenated blood runs through the internal iliac veins from the organs and walls of the basin, genitals, buttocks, back and upper thigh regions. In the external iliac veins, deoxygenated blood flows through from the lower limbs and the corresponding abdominal wall.

Inferior vena cava syndrome (IVCS) is a result of obstruction of the inferior vena cava. It is most often caused by invasion, pressure from a surrounding structure or tumor, or by thrombosis in the vein itself. Deep vein thrombosis refers to the formation of a blood clot within a deep vein. It can lead to symptoms such as swelling and pain, and even more severe life threatening complications such as pulmonary embolism. IVCS obstruction can also occur during pregnancy and lead to complications such as decreased heart rate, decrease in renal function and an increase in venous pressure. Symptoms associated with IVCS include edema of the lower extremities, tachycardia, distress, and possible supine hypotensive syndrome. Patients may even be asymptomatic, or they may present symptoms only after complications have occurred.

Treatment of IVCS obstruction depends on the cause of the obstruction, the seriousness of the symptoms, the patient’s overall health as well as their own preferences. Classifying the cause can help the clinician to make the correct diagnosis. In cases involving deep vein thrombosis, medical management may include anticoagulation therapy, thrombolytic agents or even the use of an IVC filter, which traps large blood clot formations and prevents them from traveling through the vena cava to the heart and lungs. It is essential that the patient receive the most appropriate form of treatment in order to prevent further complications (which can be severe or even fatal) from arising. 


What function does the inferior vena cava serve?

The inferior vena cava is solely responsible for collecting and transporting deoxygenated blood from the lower portion of the body (lower limbs and all organs located below the diaphragm) into the right atrium of the heart. The right atrium is located on the lower right back side of the heart. The corresponding vein that carries deoxygenated blood from the upper portion of the body is known as the superior vena cava.