Evidence summary
Time to delivery is shortened with combined therapy
Two recent high-quality meta-analyses investigated the effect of adding oxytocin to transcervical Foley balloon placement for cervical dilation. A network meta-analysis, including 30 RCTs (with 6465 pregnant patients), examined the efficacy of multiple combinations of cervical ripening methods.1 A subset of 7 trials (n = 1313) compared oxytocin infusion with transcervical Foley (inflated to 30-60 mL) to Foley alone. Patients were at > 24 weeks’ gestation with a live fetus and undergoing elective or medical induction of labor; exclusion criteria were standard contraindications to vaginal delivery.
Compared to Foley alone, Foley plus oxytocin reduced both the time to the primary outcome of vaginal delivery (mean duration [MD] = –4.2 h; 95% CI, –1.9 to –6.5) and the time to overall (vaginal and cesarean) delivery (MD = –3.1 h; 95% CI, –1.5 to –4.6). There were no differences in rates of cesarean section, chorioamnionitis, epidural use, or neonatal intensive care unit admission. This analysis did not stratify by parity.1
In a standard meta-analysis, researchers identified 6 RCTs (N = 1133) comparing transcervical Foley balloon and oxytocin to Foley balloon alone for cervical ripening in pregnant patients at > 23 weeks’ gestation (1 trial was limited to patients at > 37 weeks’ gestation).2 Foley balloons were inflated with 30 to 60 mL saline, and oxytocin infusions started at 1 to 2 mU/min and were titrated up to 10 to 40 mU/min. Balloon time was usually 12 hours, but not always stated.
The authors found no statistically significant difference in cesarean rates (the primary outcome) between Foley plus oxytocin vs Foley alone (relative risk [RR] = 0.91; 95% CI, 0.76-1.1). Overall delivery within 12 hours was more likely with combined therapy (RR of remaining pregnant = 0.46; 95% CI, 0.34-0.63), but delivery at 24 hours was not (RR = 0.94; 95% CI, 0.92-1.05). However, in a sub-analysis by parity, nulliparous women who received combined therapy had higher overall delivery rates in 24 hours than did multiparous women (RR = 0.77; 95% CI, 0.62-0.97).2
Adding oxytocin may allow shorter transcervical balloon times
One recent RCT (N = 177) compared labor induction with oxytocin and a single trans-cervical balloon (Cook catheter with only the intrauterine balloon inflated) removed at either 6 or 12 hours.3 Patients were pregnant women (mean age, 31 years) with a term singleton vertex pregnancy, a Bishop score ≤ 6, and no contraindications to vaginal delivery. All patients received a balloon inflated to 60 mL with an oxytocin infusion (2-30 mU/min). The intervention group had the balloon removed at 6 hours, while the control group had it removed at 12 hours.
The mean Bishop score changed by 6 points in each group. Time to overall delivery (the primary outcome) was significantly shorter with 6 hours of balloon time than with 12 hours (19.2 vs 24.3 h; P < .04). Overall delivery within 24 hours was also significantly more likely in the 6-hour group (67.4% vs 47.4%; P < .01), although vaginal delivery in 24 hours did not change (74% vs 59%; P = .07). No differences were seen in cesarean delivery rates or maternal or neonatal morbidity rates.
A look at fixed-dose vs titrated oxytocin
Another RCT (N = 116) examined the effectiveness of cervical ripening using a Foley balloon plus either fixed-dose or titrated low-dose oxytocin.4 Patients (mean age, 26 years) had singleton pregnancies at ≥ 37 weeks’ gestation with a Bishop score < 6 and presented for induction of labor. Foley balloons were inflated to 30 mL, and patients received either a fixed oxytocin infusion of 2 mU/min or a titrated infusion starting at 1 mU/min, increasing by 2 mU/min every 30 minutes to a maximum of 20 mU/min.
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