What causes hemolysis?

• A. Shaking the specimen and using too small a needle
• B. Using proper technique
• C. Delay in processing
• D. High ambient temperature only

Answer: (A)

Hemolysis happens when red blood cells rupture, releasing hemoglobin into the plasma or serum. The most direct way this occurs during collection is mechanical stress on the cells. Shaking the specimen applies force that can break the fragile cell membranes, and drawing through a needle that’s too small increases shear forces as blood is forced through a narrow opening. Together, these actions physically damage the cells and cause hemolysis, which can then distort many test results. Using proper technique—gentle handling, an appropriately sized needle, and careful mixing rather than vigorous shaking—helps prevent this. While delays in processing or high temperatures can also affect samples, the described mechanical handling is the primary cause in this scenario.