Intra- and inter-centre standardisation of thromboelastography (TEG®)

Thromboelastography is used for assessment of coagulation and to guide administration of blood products peri-operatively. There is currently no method of standardisation in the UK, nor an approved method of proving quality. We investigated the reproducibility of thromboelastography by testing whole blood with no coagulation abnormality in three phases. Where a single operator performed multiple assays on the same blood sample at a single location, we found considerable variation, with 21% of R- and 25% of K-time measurements lying outside a set tolerance range (median ± 20%). Where samples were analysed by different operators in a single location, this finding was repeated. Where blood was transported in a citrated form for simultaneous analysis in multiple locations, results were more consistent, suggesting improved stability. Across all phases of testing there was good reproducibility of the maximum amplitude. Further examination of the results indicated less variation where analysis was performed on blood taken from the same kaolin vial compared with results from different vials. Our preliminary study indicates that R- and K-times may be highly variable, which we hypothesise may be due to variable mixing of blood and kaolin. We intend to repeat this study in the context of coagulopathy, where variability in results could potentially impact upon transfusion practice.