Misoprostol May Be Effective Oxytocin Alternative

Misoprostol May Be Effective Oxytocin Alternative

Misoprostol is a safe and effective alternative to titrated intravenous for addressing abnormalities of the active phase of labor, according to new research published in Obstetrics and Gynecology.

Based on misoprostol’s uterotonic properties, Dr. April T. Bleich, from the department of obstetrics and gynecology at the University of Texas Southwestern Medical Center at Dallas, and colleagues hypothesized that misoprostol would be a logical option for labor augmentation. In their controlled study, women were randomized to receive oxytocin (N=174) prepared as a 20 unit/L solution in isotonic saline and administered by using calibrated infusion pumps or to misoprostol (N=176) given 75 micrograms orally, up to two doses 4 hours apart. (Bleich and colleagues conducted a previous study and determined this dose produced sufficient uterine activity while minimizing uterine tachysystole and hypertonus). Women included in the study were at least 16 years old and had the following characteristics: gestational age 36 weeks or more, singleton, cephalic presentation, reassuring fetal heart rate, cervical dilation between 4 and 8 cm.

Bleich et al. found that the type of delivery did not differ significantly between groups, with cesarean delivery rates of 10% and 11% for women in the misoprostol and oxytocin groups, respectively. They also noted a higher overall incidence of uterine tachysystole, hypertonus, or both in the misoprostol as compared with participants in oxytocin group. However, this uterine activity was not associated with emergency cesarean delivery or with any other adverse maternal or neonatal outcomes.

Authors acknowledged that the study was limited by the fact that it was not blinded, and that it was not sufficiently powered to detect uncommon neonatal outcomes or such adverse maternal outcomes as postpartum hemorrhage, uterine atony, and the need for cesarean hysterectomy. As such, they believe clinicians should remain optimistic but cautious regarding their findings.

“We are of the view that our study suggests that oral misoprostol is an effective agent for augmentation of labor, although this study has not established its safety when uncommon outcomes are considered,” Bleich and colleagues concluded.

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Bleich AT, Villano KS, Lo JY, et al. Oral misoprostol for labor augmentation: a randomized controlled trial. Obstet Gynecol. 2011;118(6):1255-60.

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