What is the role of a tourniquet in the blood collection process?

In the blood collection process, the role of a tourniquet is to aid in locating the vein by temporarily restricting blood flow. When applied, the tourniquet creates a buildup of blood in the veins, making them more prominent and easier to see and palpate. This vascular engorgement allows the healthcare provider to accurately identify the best site for venipuncture, thereby increasing the chances of successful blood draw on the first attempt.

The tourniquet is designed to restrict venous blood flow while allowing arterial flow to continue, leading to a visible swelling of the veins. This technique is particularly beneficial when the veins are difficult to locate, ensuring a smoother and more efficient blood collection process. It is important to note that the tourniquet should not be left on for extended periods, as prolonged restriction can lead to complications or complications in the sample's quality.