Major obstetric haemorrhage: monitoring with thromboelastography, laboratory analyses or both?

BACKGROUND: Haemorrhage is a common cause of morbidity and mortality in the obstetric population. The aim of this study was to compare the use of thromboelastography and laboratory analyses to evaluate haemostasis during major obstetric haemorrhage. A secondary aim was to evaluate correlations between the results of thromboelastography, laboratory analyses and estimated blood loss.

METHODS: Forty-five women with major obstetric haemorrhage and 49 women with blood loss <600 mL were included. The following thromboelastography analyses were performed: time to start of clotting (TEG-R), time to 20 mm of clot firmness (TEG-K), rate of clot growth (TEG-Angle), maximum amplitude of clot (TEG-MA) and lysis after 30 min (TEG-LY30). In addition, platelet count, activated partial thromboplastin time, prothrombin time, fibrinogen, antithrombin and D-dimer were measured.

RESULTS: Thromboelastography variables reflecting clot stability and fibrinolysis were decreased in women with massive obstetric haemorrhage compared to women with normal bleeding, while clot initiation was accelerated. Laboratory analyses also showed impaired haemostasis with the most pronounced differences in platelet count, fibrinogen concentration and antithrombin activity. The strongest correlations existed between fibrinogen and TEG-MA and between estimated blood loss and TEG-MA, fibrinogen and antithrombin, respectively.

CONCLUSIONS: Impaired haemostasis, demonstrated by thromboelastography and laboratory analyses, was found after an estimated blood loss of 2000 mL. Thromboelastography provides faster results than standard laboratory testing which is advantageous in the setting of on-going obstetric haemorrhage. However, laboratory analyses found greater differences in coagulation variables, which correlated better with estimated blood loss.