Understanding Venous Disease Inferior vena cava syndrome, or IVCS, refers to a sequence of signs and symptoms related to obstruction or compression of the inferior vena cava (IVC), a large vein that carries blood from the lower and middle part of the body back to the heart. Iliofemoral venous obstruction is a partial or complete blockage of the iliac and femoral veins (In the pelvis and thigh). See more