• Use of tubes or syringes or wet clean.
  • Inappropriate use of anticoagulants or wrong proportion.
  • Ligature placement for a very long time before the puncture.
  • Perforation of the deep vein with the formation of a hematoma and subsequent tissue injury, which by producing histic input factors in the blood can dilute the sample and also accelerate the process of blood clotting.
  • Removing blood clot too slowly with part of the blood in the syringe or collection tube.


  • Introduction of the blood collection tube for emptying the syringe under pressure and with the needle attached, which facilitates the formation of foam and the onset of hemolysis.
  • Excessive agitation of the mixture blood – anticoagulant foaming (hemolysis) or insufficient agitation with microclots appearance.


  • Patient identification errors when performing the sampling.
  • Insufficient filling of the tubes that contain a certain proportion of anticoagulant.
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