An in vitro investigation of the coagulation effects of exogenous oxytocin using thromboelastography in healthy parturients.

Background: We investigated the coagulation effects in vitro of exogenous oxytocin in whole blood of healthy term parturients.

Methods: Thromboelastography (TEG®) was performed on kaolin-activated citrated blood samples from 25 healthy, term, nonlaboring parturients. We compared the in vitro effects on the maternal thromboelastographic profile of 3 different exogenous oxytocin concentrations (22.5, 30.1, and 32.9 μU/mL) and a control (0 μU/mL). These exogenous oxytocin concentrations were chosen to approximate maternal plasma oxytocin concentrations during elective cesarean delivery, vaginal delivery, and nonelective cesarean delivery, respectively.

Results: Increasing the oxytocin concentration was significantly associated with hypercoagulable effects as observed with TEG® (decreasing reaction time, clot formation time, and Tmax; increasing α angle and maximum rate of thrombus generation). Compared with control samples, the median percentage change (interquartile range) in TEG® values for samples with the highest exogenous oxytocin concentration (32.9 μU/mL) was largest for reaction time: -40.3% (-45.8%, -22.2%); and Tmax: -39.2% (-42.9%, -28.5%).

Conclusion: The results of this in vitro investigation suggest that exogenous oxytocin is associated with modest hypercoagulable effects in the maternal blood of healthy term parturients.