Which factor is a known contributor to hemolysis during collection?

• A. Using a small-gauge needle.
• B. Using a large-gauge needle.
• C. Gentle mixing after collection.
• D. Drawing from an IV line.

Answer: (A)

Hemolysis during collection happens when red blood cells are subjected to mechanical stress as they’re drawn into the collection system. Using a thinner needle creates a narrow pathway, which speeds the blood flow and increases shear forces on the cells as they pass through the needle and into the evacuated tube. That higher shear can rupture cell membranes, releasing hemoglobin and yielding a hemolyzed sample. A larger-diameter needle reduces these stresses, allowing the blood to flow with less turbulence and damage. The other options don’t reflect the same direct mechanical cause: gentle mixing helps avoid other sample issues, and drawing from an IV line can introduce dilution or contamination rather than the primary shear-related damage that comes from a small needle.