Obstetric hemorrhage and coagulation: an update. Thromboelastography, thromboelastometry, and conventional coagulation tests in the diagnosis and prediction of postpartum hemorrhage.

Globally, postpartum hemorrhage (PPH) is the leading cause of maternal morbidity and mortality. In the current treatment of severe PPH, first-line therapy includes transfusion of packed cells and fresh-frozen plasma in addition to uterotonic medical management and surgical interventions. In persistent PPH, tranexamic acid, fibrinogen, and coagulation factors are often administered. Secondary coagulopathy due to PPH or its treatment is often underestimated and therefore remains untreated, potentially causing progression to even more severe PPH. In most cases, medical and transfusion therapy is not based on the actual coagulation state because conventional laboratory test results are usually not available for 45 to 60 minutes. Thromboelastography and rotational thromboelastometry are point-of-care coagulation tests. A good correlation has been shown between thromboelastometric and conventional coagulation tests, and the use of these in massive bleeding in nonobstetric patients is widely practiced and it has been proven to be cost-effective. As with conventional laboratory tests, there is an influence of fluid dilution on coagulation test results, which is more pronounced with colloid fluids. Fibrinogen seems to play a major role in the course of PPH and can be an early predictor of the severity of PPH. The FIBTEM values (in thromboelastometry, reagent specific for the fibrin polymerization process) decline even more rapidly than fibrinogen levels and can be useful for early guidance of interventions. Data on thromboelastography and thromboelastometry in pregnant women are limited, particularly during the peripartum period and in women with PPH, so more research in this field is needed.