Changes in thromboelastography parameters in pregnancy, labor, and the immediate postpartum period.

OBJECTIVE: To demonstrate changes in clot mechanics during pregnancy, and to determine the effect that delivery has on immediate postpartum thromboelastography parameters. METHODS: In an observational cross-sectional/longitudinal study, thromboelastography was performed on whole blood aliquots obtained from women carrying singleton pregnancies attending a center in London, UK, between December 2013 and March 2014. Thromboelastography was repeated 6hours after delivery among patients recruited in the third trimester or labor. Bleeding questionnaires were completed and routine clinical/demographic data obtained. RESULTS: Overall, 112 women were included. The thromboelastography parameters were significantly correlated with length of pregnancy. From the third trimester to the postpartum period, there was a significant decrease in time until fibrin formation (R value; 5.8 vs 5.0minutes, P=0.036) and in time to reach a certain clot strength (amplitude of 20mm; K value; 1.3 vs 1.1minutes, P=0.007). From established labor to after delivery, there was a significant increase in clot lysis at 60minutes after the maximum amplitude of clot formation (LY60; 1.8% vs 3.1%, P=0.001). CONCLUSION: The present study describes a novel finding regarding changes in clot mechanics in late pregnancy/puerperium and supports the concept of using thromboelastography as part of the routine assessments at delivery.