ASCP (American Society for Clinical Pathology) Phlebotomy Technician Certification Practice Exam

The primary purpose of a tourniquet during venipuncture is to decrease blood flow temporarily. When the tourniquet is applied, it restricts venous blood return to the heart, which leads to an accumulation of blood in the veins of the area, causing them to engorge and become more prominent. This engorgement makes it easier for the phlebotomist to locate and access the veins for blood collection.

While stabilizing the arm and making veins more prominent are benefits of using a tourniquet, they are secondary effects rather than the primary purpose. Similarly, using a tourniquet to distract the patient is not relevant to its primary function and does not apply to the clinical procedure's goals. The main role remains focused on temporarily reducing blood flow to facilitate the venipuncture process more effectively.