What is the primary reason for using a tourniquet during venipuncture?

Using a tourniquet during venipuncture is fundamental for making veins more prominent. When a tourniquet is applied above the site where blood is to be drawn, it restricts venous blood flow, causing the veins to engorge with blood temporarily. This process dilates the veins, making them larger and more visible, thus facilitating easier access for the needle insertion.

This is particularly advantageous for practitioners, as it enhances the chances of a successful draw on the first attempt, reducing discomfort for patients. Visibility of veins can vary greatly among individuals, and the use of a tourniquet is a standard practice that effectively aids in the identification of suitable puncture sites, especially in patients with smaller or deeper veins.