What is the purpose of using a tourniquet during venipuncture?

The purpose of using a tourniquet during venipuncture is primarily to restrict blood flow, which helps to engorge the veins and makes them more visible and easier to puncture. When the tourniquet is applied above the venipuncture site, it temporarily occludes venous return, causing increased pressure in the veins and making them stand out against the surrounding tissue. This is particularly helpful for identifying a suitable vein for collecting blood samples, especially in patients with smaller or deeper veins.

The effectiveness of a tourniquet in enhancing vein visibility is crucial for successful venipuncture, as it increases the likelihood of obtaining a good specimen while minimizing patient discomfort and complications associated with multiple attempts at venipuncture.