What is the purpose of a tourniquet in venipuncture?

The purpose of a tourniquet in venipuncture is primarily to distend veins for better visibility. When a tourniquet is applied to the upper arm, it temporarily constricts the blood flow in the veins, causing them to become engorged and more prominent. This makes it easier for the healthcare professional to locate a suitable vein for the blood draw.

By enhancing the visibility of the veins, the tourniquet facilitates a more successful and efficient venipuncture procedure, reducing the risk of multiple attempts and discomfort for the patient. Once the vein is identified and the needle inserted, the tourniquet is typically released to restore normal blood flow, which helps to decrease the risk of hematoma formation and to ensure proper blood collection.

Other options like slowing down the blood flow or preventing contamination do not accurately reflect the primary goal of using a tourniquet. Additionally, while security of the needle in place is important, it is achieved through other means, such as hand positioning and stabilization, rather than with the use of a tourniquet.