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Preanalytic Errors

Preanalytical Error

What is it?

How does it happen?

What is the result?


Red blood cells (RBCs) break and release contents of cell into plasma.

  • Needle incorrectly positioned in vein; cells forced to squeeze through opening.
  • Needle gauge too small; slow blood return into tube.
  • Vigorous mixing or shaking of tube.
  • Alcohol on skin that has not had sufficient time to dry.
  • Some test results may be falsely elevated. (Potassium is especially affected by hemolysis.)
  • Patient may have to be re-drawn.

Clotted specimen

Clumped or clotted cells in specimen that requires anticoagulated or whole blood

  • Insufficient mixing of blood with anticoagulant in tube.
  • Delay in mixing tube.
  • Slow filling tube.
  • Inaccurate test results for cell counts and clotting studies.
  • Patient may have to be re-drawn.
Tube filled to incorrect volume

Too little or too much blood in tube.

  • Tube removed from needle too quickly.
  • Vacuum in tube has been compromised due to use of tube past the expiration date (Results in a short fill).
  • Manual fill of tube may lead to over-fill.
  • Test results may be unreliable due to dilution errors.
  • Patient may have to be re-drawn.