The inferior vena cava (IVC) is the largest vein in the human body. It collects deoxygenated blood returning from the lower half of the body (below the diaphragm), including the legs, abdomen, and pelvic organs, and carries it to the right atrium of the heart.
The IVC is formed by the joining of the two common iliac veins in the abdomen and ascends along the right side of the spine before passing through the diaphragm and entering the heart. It works in conjunction with the superior vena cava (SVC), which drains blood from the upper body (head, neck, arms, and chest), to return all systemic venous blood to the right side of the heart, from where it is pumped to the lungs.
In critical care and cardiac procedures, the IVC is clinically relevant in several ways. Central venous catheters placed in the femoral vein (in the groin) have their tip in the IVC. IVC filters are occasionally inserted to catch blood clots migrating from the leg veins before they can reach the lungs. During cardiac catheterisation, right heart catheters are advanced through the IVC into the right heart to measure pressures. In cardiac arrest resuscitation, venous return (blood flowing back to the heart through the IVC and SVC) is maintained partly by effective chest compressions.
The diameter of the IVC on ultrasound, and how it changes with breathing, is used at the bedside to estimate fluid status and guide fluid management decisions in critical care.
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