Thromboelastography: a reliable test?

The thromboelastograph (TEG), a measure of global haemostasis, is routinely used during cardiac and hepatic surgery to optimize blood product selectio n and usage. It has recently been suggested that it may also be a useful to ol to screen patients with hypercoagulable states. Limited published data o n performance characteristics has led to speculation regarding its consiste ncy and, therefore, validity of the results. This study was designed to ass ess the effect of stability of blood samples prior to testing, repeated sam pling, intra- and inter-assay variability using the native, celite, tissue factor (TF) and Reopro-modified TEG. Analysis of native and celite samples after storage over 90 min showed a period of instability up to 30 min. Ther eafter, all parameters between 30 and 90 min were stable [P = not significa nt (NS)]. When the same sample was repeatedly assayed, both native and celi te TEG parameters showed a significant change towards hypercoagulability (P < 0.01), whereas the TF and Reopre-modified TEG showed no change. Intra- a nd inter-assay variability on samples tested after 30 min showed excellent reproducibility for all parameters (P = NS). The data suggest that the TEG is a useful tool in haemostasis but requires a formal standard operating pr ocedure to be adopted that takes into account the initial period of sample instability. (C) 2001 Lippincott Williams Wilkins.