Oxytocin Compared to Buccal Misoprostol for Induction of Labor after Term Prelabor Rupture of Membranes

Nulliparas at Term with Premature Rupture of Membranes and an Unfavorable Cervix: Labor Induction with Prostaglandin or Oxytocin? A Retrospective Matched Case Study

Background: Induction of labor (IOL) in nulliparas with premature rupture of membranes (PROM) and an unfavorable cervix at term poses challenges. Our study sought to investigate the impact of prostaglandin E2 (PGE2) compared to oxytocin on the duration of IOL in this specific group of parturients. Methods: This was retrospective matched-case study. All nulliparas with term PROM who underwent induction between January 2006 to April 2023 at Shaare Zedek Medical Center were identified. Cases induced by either PGE2 or oxytocin were matched by the following criteria: (1) time from PROM to IOL; (2) modified Bishop score prior to IOL ≤ 5; (3) newborn birthweight; and (4) vertex position. The primary outcome was time from IOL to delivery. Results: Ninety-five matched cases were identified. All had a modified Bishop score ≤ 5. Maternal age (26 ± 4.7 years old, p = 0.203) and gestational age at delivery (38.6 ± 0.6, p = 0.701) were similar between the groups. Matched factors including time from PROM to IOL (23.5 ± 19.2 versus 24.3 ± 21.4 p = 0.780), birth weight of the newborn (3111 g versus 3101 g, p = 0.842), and occiput anterior position (present on 98% in both groups p = 0.687) were similar. Time from IOL to delivery was significantly shorter by 3 h and 36 min in the group induced with oxytocin than in the group induced with PGE2 (p = 0.025). Within 24 h, 55 (58%) of those induced with PGE2 delivered, compared to 72 (76%) of those induced with oxytocin, (p = 0.033). The cesarean delivery rates [18 (19%) versus 17 (18%)], blood transfusion rates [2 (2%) versus 3 (3%)], and Apgar scores (8.8 versus 8.9) were similar between the groups (PGE2 versus oxytocin, respectively), p ≥ 0.387. Conclusions: Induction with oxytocin, among nulliparas with term PROM and an unfavorable cervix, was associated with a shorter time from IOL to delivery and a higher rate of vaginal delivery within 24 h, with no difference in short-term maternal or neonatal adverse outcomes.

Methods for the induction of labor: efficacy and safety

This review assessed the efficacy and safety of pharmacologic agents (prostaglandins, oxytocin, mifepristone, hyaluronidase, and nitric oxide donors) and mechanical methods (single- and double-balloon catheters, laminaria, membrane stripping, and amniotomy) and those generally considered under the rubric of complementary medicine (castor oil, nipple stimulation, sexual intercourse, herbal medicine, and acupuncture). A substantial body of published reports, including 2 large network meta-analyses, support the safety and efficacy of misoprostol (PGE1) when used for cervical ripening and labor induction. Misoprostol administered vaginally at doses of 50 μg has the highest probability of achieving vaginal delivery within 24 hours. Regardless of dosing, route, and schedule of administration, when used for cervical ripening and labor induction, prostaglandin E2 seems to have similar efficacy in decreasing cesarean delivery rates. Globally, although oxytocin represents the most widely used pharmacologic agent for labor induction, its effectiveness is highly dependent on parity and cervical status. Oxytocin is more effective than expectant management in inducing labor, and the efficacy of oxytocin is enhanced when combined with amniotomy. However, prostaglandins administered vaginally or intracervically are more effective in inducing labor than oxytocin. A single 200-mg oral tablet of mifepristone seems to represent the lowest effective dose for cervical ripening. The bulk of the literature assessing relaxin suggests this agent has limited benefit when used for this indication. Although intracervical injection of hyaluronidase may cause cervical ripening, the need for intracervical administration has limited the use of this agent. Concerning the vaginal administration of nitric oxide donors, including isosorbide mononitrate, isosorbide, nitroglycerin, and sodium nitroprusside, the higher incidence of side effects with these agents has limited their use. A synthetic hygroscopic cervical dilator has been found to be effective for preinduction cervical ripening. Although a pharmacologic agent may be administered after the use of the synthetic hygroscopic dilator, in an attempt to reduce the interval to vaginal delivery, concomitant use of mechanical and pharmacologic methods is being explored. Combining the use of a single-balloon catheter with dinoprostone, misoprostol, or oxytocin enhances the efficacy of these pharmacologic agents in cervical ripening and labor induction. The efficacy of single- and double-balloon catheters in cervical ripening and labor induction seems similar. To date, the combination of misoprostol with an intracervical catheter seems to be the best approach when balancing delivery times with safety. Although complementary methods are occasionally used by patients, given the lack of data documenting their efficacy and safety, these methods are rarely used in hospital settings.

Oxytocin Versus Oral Misoprostol for Induction of Labor in Pregnant Women with Term Prelabor Rupture of Membranes: a Randomized Clinical Trial

This study compares the effectiveness and safety of oxytocin infusion against oral misoprostol for inducing labour in pregnant women with term prelabor membrane rupture. We randomized 173 pregnant women presenting with term prelabor rupture of membranes (PROM) at Ain Shams University Maternity Hospital into Group A (underwent induction of labor (IOL) by 25μg misoprostol oral tablet every 4 h, for maximum 5 doses) and an identical Group B: (underwent IOL by oxytocin infusion according to the hospital protocol). Our primary outcome was rate of vaginal delivery within 24 h, while the secondary outcomes included the time till active phase, induction to delivery interval, maternal pyrexia, nausea and vomiting, fetal distress, Apgar score, birth weight, and neonatal intensive care unit admission. Both groups showed high rates of vaginal delivery (82.4% & 87.1% for misoprostol group and oxytocin group respectively) with no significant difference between the two groups (p=0.394). However, patients induced by misoprostol took significantly less time to reach active phase with a shorter induction to delivery interval as compared to patients induced with oxytocin. This difference was clear in multiparous women, but not observed in primiparous women when subgroup analysis was done. No significant difference was found as regards other outcomes. Our study showed that both oral misoprostol and oxytocin are effective and safe for IOL in patients with PROM, with shorter induction-delivery interval in patients induced by oral misoprostol, an effect that is clear in multiparous but not primiparous women. TRIAL REGISTRATION: NCT05215873, on 31/01/2022, "retrospectively registered".

Novel Evidence-Based Labor Induction Algorithm Associated with Increased Vaginal Delivery within 24 Hours

OBJECTIVE

This study aimed to assess whether concordance with our proposed labor induction algorithm is associated with an increased rate of vaginal delivery within 24 hours.

STUDY DESIGN

We conducted a retrospective review of 287 induction of labors (IOLs) at a single urban, tertiary, academic medical center which took place before we created an evidence-based IOL algorithm. We then compared the IOL course to the algorithm to assess for concordance and outcomes. Patients age 18 years or over with a singleton, cephalic pregnancy of 36^6/7 to 42^0/7 weeks' gestation were included. Patients were excluded with a Bishop's score >6, contraindication to misoprostol or cervical Foley catheter, major fetal anomalies, or intrauterine fetal death. Patients with 100% concordance were compared with <100% concordant patients, and patients with ≥80% concordance were compared with <80% concordant patients. Adjusted hazard ratios (AHRs) were calculated for rate of vaginal delivery within 24 hours, our primary outcome. Competing risk's analysis was conducted for concordant versus nonconcordant groups, using vaginal delivery as the outcome of interest, with cesarean delivery (CD) as a competing event.

RESULTS

Patients with 100% concordance were more likely to have a vaginal delivery within 24 hours, n = 66 of 77 or 85.7% versus n = 120 of 210 or 57.1% (p < 0.0001), with an AHR of 2.72 (1.98, 3.75, p < 0.0001) after adjusting for delivery indication and scheduled status. Patients with 100% concordance also had shorter time from first intervention to delivery (11.9 vs. 19.4 hours). Patients with ≥80% concordance had a lower rate of CD (11/96, 11.5%) compared with those with <80% concordance (43/191 = 22.5%; p = 0.0238). There were no differences in neonatal outcomes assessed.

CONCLUSION

Our IOL algorithm may offer an opportunity to standardize care, improve the rate of vaginal delivery within 24 hours, shorten time to delivery, and reduce the CD rate for patients undergoing IOL.

KEY POINTS

· Studies on IOL have focused on individual steps. A labor induction algorithm allows for standardization.. · Algorithm concordance is associated with decreased time to delivery.. · Algorithm concordance is associated with decreased CD rate..

Sublingual Misoprostol versus Oxytocin to Induce Labor in Term Premature Rupture of Membranes in Pregnant Women: A Randomized Single-Blind Controlled Trial

Objective. The aim of this study was to compare maternal and neonatal outcomes between sublingual misoprostol and oxytocin on stimulating labor in term premature rupture of membranes (PROM) in pregnant women. Materials and method. This randomized single-blind control trial was conducted at Bhumibol Adulyadej Hospital (BAH), Royal Thai Air Force, Bangkok, Thailand, between September 2020 and February 2021. Subjects were term pregnant women who had PROM and came to BAH for delivery. Participants were allocated into study (misoprostol) and control (oxytocin) groups. The study and control groups were, respectively, administered sublingual misoprostol and intravenous oxytocin to induce labor. Induction time and second stage of labor were recorded. Neonatal outcomes and maternal and fetal complications were also recorded and analyzed. Result. A total of 170 women were enrolled and equally divided into study and control groups. Mean maternal age, body mass index, parity, gestational age, and bishop score of both groups were comparable. Induction time of the study group was statistically shorter than the control group (338 and 399 min, respectively). Duration of active phase (450/427 min) and the second stage (19/21 min) of labor between study and control groups were not significantly different. Cesarean section delivery rate of study was lower than the control group (13.3 and 28.8%, $p=0.002$ ). Intrapartum complications, neonatal outcomes, and intra- and postpartum complications among both groups were not significantly differentiated. There was no instance of postpartum hemorrhage or uterine rupture in the present study. Conclusion. Induction time and cesarean section rates of sublingual misoprostol group were significantly lower than the intravenous oxytocin group in full-term PROM pregnancy.