Effect of delay and storage on whole-blood clotting analysis as determined by thrombelastography.

The thrombelastogram (TEG) measures the viscoelastic properties of clotting blood, displaying a visual trace of all phases of coagulation and fibrinolysis. Thrombelastography can be performed on whole blood (WBTEG) or on citrated blood or plasma, citrated samples facilitating delayed analysis but requiring recalcification of the sample. The aim of this study was to investigate the effect of delay and storage method on WBTEG measurement. Thrombelastographic analysis of coagulation in whole blood was investigated after delays of 3 and 6 minutes in polystyrene syringes (PS3 and PS6) and 3 minutes in silicone-coated glass tubes (SG3). Thrombelastograms of the delayed samples were compared with those measured immediately. Silicone-coated glass tubes activated coagulation, as seen by shorter r times (p < 0.01), shorter r + k times (p < 0.01), and larger maximum amplitude (ma) values (p < 0.01) compared with TEG values determined immediately after sampling. In the SG3 group, 20% of samples had clotted by 3 minutes, and the use of SG tubes for this purpose cannot be recommended. A delay of 6 minutes in PS had less effect on the activation of clotting in the earlier stages in that the r time was prolonged (p < 0.01). However, there appeared to be some activation later in that k time was shorter (p < 0.01) and ma was wider (p < 0.05). Overall, a 3-minute delay in PS produced the best values.(ABSTRACT TRUNCATED AT 250 WORDS)