Reference: Obstet Gynecol 2017 Jun;129(6):1046
Induction of labor is indicated for various conditions during pregnancy, including late term pregnancy, diabetes refractory to treatment, preeclampsia, chronic hypertension, and suspected fetal compromise (Obstet Gynecol 2009 Aug;114 (2 Pt 1):386-97). Methods for induction often are based upon the Bishop score. A low Bishop score (<5) is an indicator of likely extended latent phase of labor and higher rates of cesarean delivery (Obstet Gynecol 2005 Apr;105(4):690-7). To prevent complications such as postpartum hemorrhage (PPH), chorioamnionitis, and endometritis related to extended latent phase, methods should be considered to shorten labor length (Obstet Gynecol 2005 Apr;105(4):705-9). Both the Foley catheter and oxytocin infusions are well established mechanisms to induce labor. Observational studies exploring their concurrent use have had mixed outcomes, but the concurrent use of Foley catheter and oxytocin infusion to increase delivery rate within 24 hours has not been investigated.
A randomized controlled trial of 323 women (mean age 27 years) with singleton pregnancy at ≥ 24 weeks gestation evaluated the safety and delivery outcomes of concurrent use of Foley catheter and oxytocin infusion for induction of labor. The women were randomized to either concurrent use of Foley and oxytocin infusion (defined by oxytocin infusion initiation within one hour of Foley placement) or sequential use (defined by oxytocin infusion after the Foley was expelled spontaneously or had remained in place for at least 12 hours). The randomization was generated separately for nulliparous and multiparous women to allow for power to detect differences between these groups. The primary outcome was delivery within 24 hours after Foley placement. Several pre-specified secondary outcomes were delineated including total time from induction to delivery and mode of delivery as well as maternal and fetal outcomes (complications such as tachysystole, chorioamnionitis, and postpartum hemorrhage [PPH]).
Baseline characteristics were similar among groups. The rate of vaginal delivery within 24 hours in nulliparous women was 64% in the concurrent use group vs. 43% in the sequential use group (risk ratio 1.5, 95% CI 1.12-2; NNT 5). In the multiparous group, 87% of those with concurrent use delivered within 24 hours compared to 72% of those with sequential use (risk ratio 1.22, 95% CI 1.02-1.45; NNT 7). Median time to delivery in the nulliparous group was 20.9 hours with concurrent use vs. 26.1 hours with sequential use (p < 0.001). In the multiparous group, median time to delivery was 14. 9 hours in the concurrent group vs. 18.6 hours in the sequential group (p = 0.013). In both groups, concurrent use was also associated with increased use of regional anesthesia (p < 0.01 for each) and longer duration of oxytocin infusion (p < 0.01 for each). There were no significant differences in maternal or neonatal outcomes (such as tachysystole, chorioamnionitis, PPH, and neonatal intensive care unit admission) in either the nulliparous or multiparous groups.
Induction of labor, regardless of the indication, requires consideration of available methods to ensure maternal and fetal safety and prevent adverse outcomes. This study demonstrated a significantly increased likelihood of delivery within 24 hours of catheter placement as well as a significant reduction in labor time with concurrent use of a Foley catheter and oxytocin. The validity of these results, however, is limited by methodological concerns. These include lack of blinding of both patients and the physicians administering treatment, and a lack of statistical power for subgroups (such as premature prelabor rupture of membranes or vaginal birth after cesarean delivery). Further research is needed to evaluate the effect of concurrent use on adverse fetal outcomes and additional clinically relevant maternal outcomes.
For more information, see the Labor induction and cervical ripening in Dynamed Plus. DynaMed users, see the Labor induction and cervical ripening topic in Dynamed Classic.
ALISON N. HUFFSTETLER, MD
completed her medical training at American University of the Caribbean School of Medicine and completed her Family Medicine residency at the University of Virginia. She is completing a fellowship in Public Policy as the Robert L. Phillips Jr. Fellow at Georgetown University in conjunction with the Robert Graham Center. She is interested in a career in academic medicine including full spectrum care with focus on obstetrics and women’s health.
Faculty contributions by Katharine C. DeGeorge, MD, MS.