Vena Cava: What to Know

Medically Reviewed by Jabeen Begum, MD on September 30, 2022
4 min read

The vena cava is a large vein that collects blood from either the upper or lower half of your body. It receives blood from several smaller veins. This is blood with the oxygen removed that the vena cava transports to the right side of the heart. Blockage or injury of a vena cava can have serious consequences for your health. 

A vena cava (plural: venae cavae) is a large vein that carries blood to the heart. You have two venae cavae: the superior vena cava and the inferior vena cava. Together, these large veins carry deoxygenated (with the oxygen removed) blood from all over the body to the right atrium of the heart. This blood moves to the right ventricle of the heart, which pumps it to the lungs through the pulmonary artery.

These large veins are formed by the merging of smaller veins. After the venae cavae are formed, smaller veins connect with them along their path. The blood from all over the head, arms, and chest is collected by various veins that all contribute to the superior vena cava. Similarly, the blood from the lower limbs, pelvis, and abdominal organs all reach the inferior vena cava.

When you're at rest, your heart pumps five to six liters of blood a minute. If you're exercising hard, this can go up to 35 liters a minute. The venae cavae bring this blood back.

The venae cavae are veins, so they have one job — to carry blood from all the tissues and organs of the body to the heart. 

The superior vena cava carries blood drained from the parts of the body above the diaphragm — the head, neck, arms, shoulder, and chest.

The inferior vena cava transports blood from your lower limbs, liver, digestive system, kidneys, reproductive system, and other organs and tissues of the body below the diaphragm.

The superior vena cava begins behind the sternum (breast bone) near the right first rib. It travels down and drains into the right atrium at the level of the third rib. It is a short vein about 7 centimeters long and runs close to the right lung in the space between the two lungs.

The inferior vena cava goes up the abdomen on the right side of the spine (vertebral column). After connecting with the hepatic vein, it goes through the diaphragm, the muscle that helps you breathe and separates your chest cavity from your abdomen. In the chest, the inferior vena cava lies on the right side of the space between the lungs. Reaching the heart, it opens into the right atrium.

The two venae cavae are in line with each other vertically. This allows doctors to pass a guidewire or catheter from the superior vena cava through the right atrium and into the inferior vena cava.

Any blockage of a vena cava can cause difficulty in blood flow. Blockage of the superior vena cava can cause:

  • Swelling of your upper body
  • Breathlessness
  • Cough
  • Headache
  • Angina (pain in the chest)
  • Flushing of the face
  • Difficulty swallowing

Blockage of the inferior vena cava can cause:

  • Pain and swelling in your legs
  • Weight gain
  • Back pain

If you notice any of these symptoms, you should consult your healthcare provider.

Obstruction of a vena cava reduces blood flow through it. Some conditions that cause this:

  • Tumors in the nearby organs, most often lung cancers and lymphomas
  • Blood clots
  • Birth defects

The inferior vena cava can be injured by gunshots, stab wounds, or surgery. Injury to this vein causes lots of blood to be lost quickly and can lead to death. Surgeons clamp the vein above and below the injured part and try to repair it. As a last resort, the inferior vena cava can be tied off (ligated), but this results in significant problems later.

The superior vena cava may be injured during medical procedures. Repair is challenging because clamping the superior vena cava stops blood flow from the head and brain. Outcomes can be poor.

Deep vein thrombosis (DVT) is a condition in which blood clots form in the veins of the legs and pelvis. These clots sometimes detach from their place and reach the inferior vena cava. They then pass through the right side of the heart, leading to a dangerous condition called pulmonary embolism. DVT is treated with medicines to prevent clotting. Your doctor may advise the placement of a filter in the inferior vena cava to prevent any detached blood clots from reaching the heart.

Blockage of the blood flow in a vena cava needs treatment. Obstruction caused by a tumor is treated with surgery, chemotherapy, or radiation therapy. Medicines are prescribed to reduce blood clot formation. Tubes called stents can be placed inside a blood vessel to allow blood flow.

Your venae cavae are needed for your continuing good health. To keep them healthy:

  • Be physically active.
  • Eat a diet low in saturated fats.
  • Reduce stress.
  • Get medical treatment for high blood pressure, high cholesterol, and diabetes.