Viscoelastic Testing in an Obstetric Population at High Risk of Hemorrhage

Rotational thromboelastometry (ROTEM) is a point-of-care viscoelastic test used in trauma for goal-directed transfusion. However, there are limited data on baseline ROTEM parameters in the U.S. obstetric population. Obtaining baseline parameters is a first step in implementing a goal-directed massive transfusion protocol in obstetric hemorrhage.

Our study aimed to establish pre- and postdelivery baseline parameters in a high-risk obstetric population and determine their association with postpartum hemorrhage (PPH).

Prospective observational study of patients ≥34 weeks' gestation, at high risk of PPH, admitted for delivery. INTEM, EXTEM, FIBTEM, and APTEM assays were performed at the time of admission to labor and delivery and then 2 hours after delivery. Primary outcome was pre- and postdelivery ROTEM parameters among women without PPH. A sample size of 60 women was needed for >90% power to detect at least 50% correlation between pre- and postdelivery assuming a loss of 10% of participants to follow-up.

Of 60 women in the study, 10 (17%) had PPH. Baseline characteristics were not different between those with or without PPH. Pre- and postdelivery ROTEM parameters were not significantly different except for APTEM. None of the patients who had PPH, compared with 4 (10%) of those who did not, had shortened clotting time and higher maximum clot firmness in postdelivery APTEM compared with EXTEM, a pattern suggestive of hyperfibrinolysis (p = 0.4).

In this study, we describe baseline ROTEM parameters in women at high risk of PPH. The majority of patients did not have a ROTEM pattern that is suggestive of hyperfibrinolysis, for which tranexamic acid is thought to be beneficial. Based on our findings, previously established obstetric transfusion thresholds for goal-directed massive transfusion protocols are likely valid for the majority of the obstetric population regardless of the presence of comorbidities or pregnancy complications.

· ROTEM parameters do not vary significantly before and after delivery.. · Most patients did not have a hyperfibrinolysis pattern, for which tranexamic acid is thought to be beneficial.. · Previous goal-directed obstetric transfusion thresholds are likely valid in most populations..