Thromboelastographic Assessment of the Differential Sensitivity of Three Contact Activators to Coagulation Factor Deficiencies in Hemocell Environments

Background: Thromboelastography (TEG) assesses global coagulation, but its sensitivity for factor deficiencies is reportedly low and may depend on the contact activator. However, the differential TEG sensitivity of contact activators for individual factor deficiencies in whole blood containing platelets and red blood cells remains unclear. This study assessed the relative sensitivity of three contact activators for detecting single coagulation factor deficiencies in reconstituted whole-blood samples using TEG. Methods: Reconstituted whole-blood samples with graded activities of FII, FV, FVIII, FIX, FX, FXI, and FXII were prepared by mixing platelets, plasma, and red blood cells, and analyzed by TEG using kaolin-, ellagic acid-, and colloidal silica-based activators (KL, EA and CS). Relative sensitivity was assessed via: (1) the factor activity at which R time first showed a statistically significant prolongation; (2) a novel metric, Sensitivity for Detecting Factor Deficiencies (SDFD), defined as the normalized relative change in R time, enabling comparison without reference ranges. Results: KL showed the broadest and highest sensitivity, detecting significant prolongation at the mildest deficiency levels for most factors. EA showed intermediate-to-high sensitivity and the highest sensitivity for FXII. CS was the least sensitive except for FV. Notably, the activity threshold of KL for exceeding the reference range was substantially lower than that for statistical significance. Conclusions: The sensitivity of TEG to coagulation factor deficiencies is dependent on the contact activator. KL showed the highest overall sensitivity to factor deficiencies, while EA showed the highest sensitivity for FXII deficiency under the conditions of this study. R time of KL can be significantly prolonged yet still stay within the reference range. This mismatch calls for more sensitive TEG reagents and stricter ranges.