What is the purpose of using a tourniquet during phlebotomy?

The purpose of using a tourniquet during phlebotomy is to engorge the veins and make them easier to access. When a tourniquet is applied above the site of the venipuncture, it restricts blood flow and causes the veins to fill with blood, thereby increasing their visibility and making them more prominent. This helps the phlebotomist to identify suitable veins for drawing blood, particularly in patients with smaller or deeper veins.

The other options, while related to certain aspects of the phlebotomy process, do not accurately describe the primary function of the tourniquet. For example, cleaning the skin is an important step in infection control and is achieved through antiseptic techniques rather than the use of a tourniquet. Similarly, while a tourniquet might help reduce discomfort indirectly by improving the chances of a successful venipuncture on the first attempt, its main purpose is not pain reduction. Lastly, warming the blood sample may promote better blood flow but is not a role of the tourniquet; other methods are used for warming blood if needed.