NHA Phlebotomy Certification Practice Exam

What can cause hemolysis of a blood sample?

1. Vigorously shaking the tube

2. Using expired tubes

3. Improper needle gauge

4. Insufficient blood volume

The correct answer is: Vigorously shaking the tube

Hemolysis of a blood sample occurs when red blood cells are destroyed, releasing hemoglobin into the plasma. One of the primary causes of hemolysis is the mechanical disruption of blood cells. Vigorously shaking a collection tube can create turbulence that damages the fragile membrane of red blood cells. This physical agitation can lead to the rupture of these cells, resulting in hemolysis. While there are other factors that may contribute to the hemolysis of blood samples—such as using expired tubes which may have degraded materials, using an improper needle gauge that could affect the blood cell integrity, or insufficient blood volume that might lead to increased hemodilution—the key aspect of this scenario is the action that causes immediate mechanical stress on red blood cells. Shaking the tube vigorously directly targets the integrity of these cells, making it the most accurate answer in this context.