What is the primary reason for using a tourniquet during phlebotomy?

Using a tourniquet during phlebotomy primarily serves to make veins more prominent for easier blood access. When the tourniquet is applied, it temporarily restricts venous blood flow while allowing arterial blood flow to continue. This causes the veins to become engorged with blood, making them more visible and palpable. Consequently, this enhanced visibility facilitates easier identification and access to a suitable vein for venipuncture, which is crucial for successful blood collection.

While restricting blood flow may have some impact on accuracy and may improve the visualization of veins, the main aim is to enhance the accessibility of the veins themselves. Minimizing patient movement and ensuring calmness are important considerations during the procedure, but they do not directly relate to the primary action of the tourniquet itself.