Impact of a 15-minute incubation on citrated TEG (thromboelastography) results in adult surgical patients-a prospective observational study.

Abstract

The thromboelastography (TEG) 6s Global Hemostasis Cartridge package insert recommends a 15-minute incubation of citrated blood prior to testing; however, most centers run samples immediately. Limited data are available to evaluate how incubation affects results and thus influences hemostatic transfusion decisions. In this single-center prospective study, 35 adult surgical and critical care patients were enrolled. Paired citrated samples were tested immediately upon laboratory arrival vs after a 15-minute benchtop incubation at room temperature. Primary endpoints included changes in citrated kaolin-reaction time (CK-R), kaolin with heparinase-reaction time (CKH-R), citrated kaolin-maximum amplitude (CK-MA), Citrated Rapid Thromboelastography Maximum Amplitude (CRT-MA), and citrated functional fibrinogen-maximum amplitude (CFF-MA) (fibrin-fibrinogen contribution). Paired t tests were used for analysis, and percent differences were calculated as [(Incubated - Immediate) / Incubated] × 100%. Categorical interpretation shifts (low/normal/high) were also assessed. A 15-minute incubation significantly shortened CK-R (8.5 ± 3.4 vs 7.4 ± 3.1 minutes; P < .01) and CKH-R (7.2 ± 2.7 vs 6.9 ± 2.5 minutes; P < .01), with mean percent changes of -17% and -12%, respectively. CK-MA decreased marginally (57.0 ± 16.0 vs 56.2 ± 12.4 mm; P < .01), while CFF-MA remained unchanged (P = .976). Notably, 23% of CK-R results shifted interpretation categories after incubation, whereas no CFF-MA categories changed. A 15-minute incubation significantly shortens CK-R/CKH-R and marginally decreases CK-MA, potentially normalizing hyper- or hypocoagulable readings. Omitting incubation risks misclassification and inappropriate plasma/prothrombin complex concentrate administration. Strict adherence to the manufacturer's incubation protocol is recommended except in emergencies, and local transfusion algorithms should specify whether "immediate" or "incubated" TEG cutoffs apply.