What is one purpose of using a tourniquet during blood collection?

Using a tourniquet during blood collection serves the primary purpose of enlarging the veins for easier access. When a tourniquet is applied above the site of venipuncture, it temporarily restricts blood flow, causing the veins to become engorged with blood. This increased visibility and palpability of the veins make it much easier for the healthcare provider to locate and puncture the appropriate vein, thus improving the chances of successful blood collection.

In contrast, other options do not accurately describe the function of a tourniquet. For instance, while sterilizing the puncture site is essential for preventing infections, this is achieved through the use of antiseptic solutions rather than the application of a tourniquet. Tourniquets do not serve to increase blood pressure in a clinical context; they are intended to facilitate venous access, not to influence systemic blood pressure. Lastly, while preventing contamination of the sample is crucial, this is managed through proper technique and equipment sterilization, rather than through the use of a tourniquet. Therefore, the correct answer highlights the role of the tourniquet in optimizing venous access for blood collection.