What is the primary purpose of using a tourniquet during a blood draw?

The primary purpose of using a tourniquet during a blood draw is to access a vein more easily. When a tourniquet is applied, it temporarily restricts blood flow in the veins of the arm, causing the veins to become more prominent and easier to locate. This makes it simpler for the phlebotomist to identify and puncture a suitable vein for drawing blood. With the increased visibility and engorgement of the veins, the procedure can be conducted more efficiently, which is critical for both patient comfort and the successful collection of the blood sample.

While minimizing pain, ensuring blood flows into the tube, and maintaining cleanliness and sterility are all important considerations during a blood draw, they are secondary to the primary goal of facilitating access to the vein.