What is the role of a tourniquet during blood collection?

The role of a tourniquet during blood collection is to constrict blood flow and make veins more prominent. When a tourniquet is applied above the site of venipuncture, it temporarily restricts the venous blood flow. This causes the blood to accumulate in the veins, thereby distending them and making them easier to locate and access with a needle. This is particularly important in individuals with small or difficult-to-access veins.

The prominence of the veins increases the likelihood of successful blood draw and minimizes the risk of multiple punctures. Proper placement and use of the tourniquet are critical to ensure an effective collection process while also minimizing potential discomfort for the patient.