What does occluding a vein for venipuncture accomplish?

The correct answer is that occluding a vein for venipuncture allows blood to pool in the site. By applying pressure to the vein, you temporarily restrict the flow of blood back to the heart, which causes blood to accumulate in the vein. This pooling makes the veins more prominent and easier to locate and puncture for blood collection. It essentially enhances the visibility and accessibility of the vein for venipuncture, making the procedure more efficient.

This technique is critical in ensuring that the procedure can be performed quickly and with greater accuracy, reducing the number of attempts needed to obtain a sample and minimizing stress for the animal.