Early vs. delayed amniotomy in individuals undergoing pre-induction cervical ripening with transcervical Foley balloon: a meta-analysis

Abstract

Objectives: To systematically review randomized controlled trials (RCTs) and perform a meta-analysis comparing early amniotomy with delayed amniotomy in individuals undergoing pre-induction cervical ripening by Foley balloon. The primary outcome was the rate of cesarean delivery. Understanding the impact of the timing of amniotomy on the rate of cesarean delivery is crucial for obstetricians and healthcare providers when making decisions about the management of labor induction.

Data sources: Data were sourced from electronic databases, including PubMed, OVID, Cochrane Library, Web of Science, and ClinicalTrials.gov through February 2024. The review adhered to Preferred Reporting Item for Systematic Reviews guidelines and registered with PROSPERO (ID CRD42023454520).

Study eligibility criteria: Inclusion criteria comprised RCTs comparing early amniotomy with delayed amniotomy in individuals undergoing cervical ripening by Foley balloon. Early amniotomy was defined as amniotomy soon after cervical ripening. Delayed amniotomy was defined as withholding amniotomy until after the onset of the active phase of labor, until at least 4 hours from either initiation of oxytocin or Foley balloon removal/expulsion, or until achieving >4 cm of dilation. Participants included nulliparous or multiparous individuals with singleton pregnancies undergoing labor induction at 37 weeks or later.

Study appraisal and synthesis: A systematic literature search was conducted using defined search terms including "early amniotomy," "delayed amniotomy," "induction of labor," "cervical ripening," and "Foley balloon," and "Foley catheter." The quality of the included trials was assessed using the Cochrane Risk of Bias Tool for randomized controlled trials. The primary outcome was cesarean delivery. Secondary outcomes included outcomes related to labor duration and neonatal outcomes. Pooled relative risks (RR) and weighted mean differences (WMD) with 95% confidence intervals were calculated.

Results: Five trials involving 849 participants undergoing induction and cervical ripening by Foley balloon were included. The rate of cesarean delivery did not differ between individuals randomly assigned to the early amniotomy group compared with those assigned to the delayed amniotomy group (22.9% vs. 23.3%; RR 1.00; 95% CI 0.65-1.55). Early amniotomy compared to delayed amniotomy was associated with a higher proportion of delivery within 24 hours (79.9% vs. 67.1%; RR 1.19; 95% CI 1.04-1.36). Early amniotomy compared with delayed amniotomy was associated with a shorter interval from oxytocin to delivery (WMD -1.5 hours; 95% CI -2.1 to -0.8), from Foley expulsion to vaginal delivery (WMD -2.5 hours; 95% CI -4.8 to -0.1), and from the start of oxytocin to vaginal delivery (WMD -1.8 hours; 95% CI -3.2 to -0.4). Other outcomes were not significantly different.

Conclusion: Early amniotomy following cervical ripening by Foley balloon in individuals with singleton pregnancies did not impact rates of cesarean delivery compared with delayed amniotomy but led to shorter duration for various labor progress outcomes.

Keywords: Cesarean delivery; Early artificial rupture of membranes; Labor induction; Randomized Controlled Trial.