What is the primary purpose of using a tourniquet during venipuncture?

The primary purpose of using a tourniquet during venipuncture is to make veins more visible and easier to puncture. When the tourniquet is applied, it temporarily restricts venous blood flow while allowing arterial blood to continue to flow into the arm. This causes the veins to become engorged with blood, making them bulge and more prominent beneath the skin, which aids the healthcare professional in locating a suitable vein for the needle insertion.

The application of a tourniquet enhances the chances of successful venipuncture by ensuring that the selected vein is secure and easily accessible. While the other options may have some relevance in different contexts, they do not reflect the primary function of the tourniquet as effectively as its role in vein visibility and accessibility.