Uterine and fetal Doppler flow changes after misoprostol and oxytocin therapy for induction of labor in post-term pregnancies.

OBJECTIVES: To compare the effect of misoprostol vs. oxytocin on blood flow in uteroplacental circulation during labor induction. METHODS: Ninety-one women with indications for induction of labor were assigned to receive either misoprostol 50 microg per vagina every 4 h as needed or intravenous oxytocin by means of a randomization table generated by computer. Doppler velocimetry of umbilical, uterine and arcuate arteries was performed immediately before and 2-3 h after administration of misoprostol or oxytocin. Pulsatility index (PI), resistance index (RI) and systolic/diastolic (S/D) ratios were measured for these arteries. The SAS system was used to perform statistical analysis. RESULTS: There were no significant changes of PI, RI and S/D ratios in umbilical arteries during misoprostol and oxytocin inductions. Vaginal application of misoprostol significantly increased PI, RI and S/D ratios in arcuate arteries and S/D ratio in uterine arteries. CONCLUSIONS: Our results indicate that intravaginal misoprostol administration increases uteroplacental resistance but probably does not substantially affect placental perfusion.