Inferior vena cava (thoracic part)

Vena cava inferior (pars thoracica) · Dolní dutá žíla (hrudní část)

Veins

Looks like

The last short stretch of the body's largest vein, passing through the diaphragm into the bottom of the right atrium.

Brings all the blood from the legs, pelvis and abdomen back into the heart.

Pressure here rises in right-heart failure, swelling the liver and legs. Very rarely, kidney or liver cancers grow up it towards the heart.