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

Using a tourniquet during venipuncture serves primarily to help locate veins. When a tourniquet is applied above the site of the intended needle insertion, it temporarily restricts venous blood flow. This restriction causes the veins to fill with blood, making them more prominent and easier to locate and access for drawing blood. The enhanced visibility of the veins allows the healthcare professional to select an appropriate site for the venipuncture, improving the chances of a successful blood draw on the first attempt.

While reducing discomfort, preventing blood clotting, and increasing blood flow may be relevant in certain contexts, these aspects are not the primary function of a tourniquet during this procedure. The main goal is to facilitate easier identification and access to the veins, ensuring a smoother and more efficient process for both the patient and the technician.