American Medical Certification Association (AMCA) Phlebotomy Practice Exam

When should the tourniquet be released during a blood draw?

1. Before inserting the needle

2. Once blood flow has been established

3. After the first specimen is drawn

4. When the patient expresses discomfort

The correct answer is: Once blood flow has been established

Releasing the tourniquet once blood flow has been established is crucial for several reasons. The primary purpose of the tourniquet is to engorge the veins, making them easier to locate and puncture. However, once blood flow begins, keeping the tourniquet applied can lead to complications such as hemoconcentration, where the blood cells concentrate within the sample, potentially causing inaccurate test results. Additionally, prolonged application can increase discomfort for the patient, and may elevate potassium levels due to the stasis of blood flow. Releasing the tourniquet at this point ensures that the specimen obtained is of good quality and reduces the likelihood of complications during the blood draw. Prior to blood flow, during the procedure, or based on patient feedback are not the appropriate times to release it, as they do not contribute to the optimal conditions for collecting a sample.