During which phase of a blood draw should a tourniquet be applied?

Applying a tourniquet should occur before needle insertion during a blood draw. This action is vital because it temporarily constricts blood flow in the veins, making them more prominent and easier to access. By engorging the veins with blood, the technician can better visualize and palpate the vein, which increases the chances of a successful venipuncture.

Using the tourniquet at this stage helps prepare the site for the blood draw, ensuring that the technician can accurately identify a suitable vein, reducing the risk of multiple attempts and minimizing discomfort for the patient.

Other phases mentioned are not appropriate for tourniquet application. For example, applying it after blood is drawn could lead to complications such as hemoconcentration, which can affect test results. Using it during the healing process is unnecessary and inappropriate, as the tourniquet's purpose is to facilitate access to the vein before drawing blood, not afterward.