The structure that does not cross the midline is -
In the left side, inferior phrenic vein, suprarenal vein, and the gonadal vein drains into left renal vein, whereas on the right side, they drain into inferior vena cava directly. So they do not cross the midline on the left side.
Left gonadal vein
Left renal vein
Left branchiocephalic vein
Hemiazygos vein