///2010 Abstract Details
2010 Abstract Details2018-05-01T17:52:49+00:00

In vitro effects of oxytocin on the coagulaton profile of parturients using thromboelastography.

Abstract Number: 9
Abstract Type: Original Research

Alexander Butwick F.R.C.A.1 ; Scott Harter M.D.2

Introduction:

Oxytocin is used routinely in obstetric practice as prophylaxis to reduce postpartum bleeding following delivery.(1) However there is limited understanding of the interaction and potential effects of oxytocin on the coagulation system.(2) The aim of this in vitro study was to assess the coagulation effects of exogenous oxytocin on whole blood of pregnant patients using thromboelastography (TEG). The calculated oxytocin concentrations used in this study were based on maternal plasma oxytocin concentrations during vaginal delivery (VD), elective cesarean delivery (CS1) and non-elective cesarean delivery (CS2).(3)

Methods:

Following IRB approval, 25 patients with uncomplicated singleton pregnancies at term (37-41 wks) for elective induction of labor (IOL) were enrolled. Prior to commencing IOL, venous blood (4.5 ml) was collected in a citrated tube (0.5ml 0.105M). For each patient, four different solutions containing citrated blood (CB) were produced in separate vials as follows: 1 ml CB (control); 1 ml + 23 μU of oxytocin (Ox-CS1); 1ml CB +34 μU of oxytocin (Ox-CS2); 1 ml+31 μU of oxytocin (Ox-VD).(3) After mixing by inversion 8-10 times, 360 μL of kaolin-activated whole blood was pipetted into a plastic cup in a pre-warmed TEG machine. Each sample was recalcified with 10 L of CaCl2, and TEG analysis was commenced within 1 minute of reconstituted sample preparation. Data was analyzed using one-way ANOVA or χ-squared tests; P value < 0.05 was considered significant.

Results:

TEG data are shown in Table 1. The r times were significant increased with Ox-VD and Ox-CS2 versus Ox-CS1 and the control group respectively (P <0.001). Values for α angle, maximum amplitude, maximum rate of thrombin generation and thrombin generated (VCurve) were similar in all oxytocin and control groups. Tmax values were significantly shorter in Ox-Vd and Ox-Cs2 groups versus Ox-Cs1 and control groups respectively (P < 0.05) (Table 1).

Discussion: The results of our in vitro TEG study indicate that modest hypercoagulable changes occur with oxytocin concentrations at 31 μU/ml and 34 μU/ml compared to 23 μU/ml and controls using whole citrated blood from term pregnant patients. Further work is needed to assess the potential effects of iv oxytocin on the coagulation system in the postpartum period following VD, CS1 and CS2.

References:

1. Curr Opin Obstet Gynecol 2004;16:143-50. 2. Eur J Pharmacol 1997;323:205-13.

3. Arch Gynecol Obstet 1987;241:13-23.



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