| Preanalytical Error | What is it? | How does it happen? | What is the result? |
| Hemolysis | 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.
|
