Phlebotomy: Effects of vigorous mixing of blood vacuum tubes on laboratory test results


Intravenous literature: Lima-Oliveira, G., Lippi, G., Salvagno, G.L., Montagnana, M., Gelati, M., Volanski, W., Boritiza, K.C., Picheth, G. and Guidi, G.C. (2012) Effects of vigorous mixing of blood vacuum tubes on laboratory test results. Clinical Biochemistry. Nov 10. .


OBJECTIVE: To evaluate the effect of tubes mixing (gentle vs. vigorous) on diagnostic blood specimens collected in vacuum tube systems by venipuncture.

DESIGN AND METHODS: Blood was collected for routine coagulation, immunochemistry and hematological testing from one hundred volunteers into six vacuum tubes: two 3.6mL vacuum tubes containing 0.4mL of buffered sodium citrate (9NC) 0.109mol/L: 3.2W/V%; two 3.5mL vacuum tubes with clot activator and gel separator; and two 3.0mL vacuum tubes containing 5.9mg K(2)EDTA (Terumo Europe, Belgium). Immediately after the venipuncture all vacuum tubes (each of one additive type) were processed through two different procedures: i) Standard: blood specimens in K(2)EDTA- or sodium citrate-vacuum tubes were gently inverted five times whereas the specimens in tubes with clot activator and gel separator were gently inverted ten times, as recommended by the manufacturer; ii) Vigorous mix: all blood specimens were shaken up vigorously during 3-5seconds independently of the additive type inside the tubes. The significance of the differences between samples was assessed by Student’s t-test or Wilcoxon ranked-pairs test after checking for normality. The level of statistical significance was set at P<0.05.

RESULTS: No significant difference (P<0.05) was detected between the procedures for all tested parameters. Surprisingly only a visual alteration was shown by the tubes mixed vigorously.

CONCLUSION: Our results drop out a paradigm suggesting that the incorrect primary blood tubes mixing promotes laboratory variability. We suggest that similar evaluation should be done using other brands of vacuum tubes by each laboratory manager.

Main page


Comments are closed.