What is the purpose of a tourniquet during venipuncture?

The purpose of a tourniquet during venipuncture is to constrict blood flow, which enhances the visibility of the veins. When a tourniquet is applied, it temporarily occludes venous return while maintaining arterial supply, leading to engorgement of the veins. This makes them more prominent and easier to locate for the phlebotomist, thereby facilitating the successful insertion of the needle.

While enhancing blood flow to the site may seem beneficial, the specific function of a tourniquet is to minimize venous flow rather than enhance it. The tourniquet does not prevent movement per se, as it is mainly focused on making veins more accessible. Additionally, it does not directly reduce pain; while a properly performed venipuncture may involve less discomfort, the primary role of the tourniquet is focused on vein accessibility rather than patient comfort.