Severe perineal lacerations in induction of labor versus expectant management: A systematic review and meta-analysis of randomized controlled trials

Abstract

Objective: This study aimed to evaluate if induction of labor (IOL) is associated with an increased risk of severe perineal laceration.

Data sources: A systematic search was conducted in MEDLINE, Ovid, Scopus, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials, and CINHAL using a combination of keywords and text words related to "induction of labor," "severe perineal laceration," "third-degree laceration," "fourth-degree laceration," and "OASIS" from inception of each database until January 2023.

Study eligibility criteria: We included all randomized controlled trials (RCTs) comparing IOL to expectant management of a singleton, cephalic pregnancy at term gestation that reported rates of severe perineal laceration.

Study appraisal and synthesis and methods: The primary outcome of interest was severe perineal laceration, defined as 3rd- or 4th-degree perineal lacerations. We conducted meta-analyses using the random effects model of DerSimonian and Laird to determine the relative risks (RR) or mean differences with 95% confidence intervals (CIs). Bias was assessed using guidelines established by Cochrane Handbook for Systematic Reviews of Interventions.

Results: A total of 11,187 unique records were screened and ultimately eight RCTs were included, involving 13,297 patients. There was no statistically significant difference in the incidence of severe perineal lacerations between the IOL and expectant management groups (209/6655 [3.1%] vs 202/6641 [3.0%]; RR 1.03, 95% CI 0.85, 1.26). There was a statistically significant decrease in the rate of cesarean birth (1090/6655 [16.4%] vs 1230/6641 [18.5%], RR 0.89, 95% CI 0.82, 0.95) and fetal macrosomia (734/2696 [27.2%] vs 964/2703 [35.7%]; RR 0.67: 95% CI 0.50, 0.90) in the IOL group.

Conclusion: There is no significant difference in the risk of severe perineal lacerations between IOL and expectant management in this meta-analysis of RCTs. Furthermore, there is a lower rate of cesarean births in the IOL group, indicating more successful vaginal deliveries with similar rates of severe perineal lacerations. Patients should be counseled that in addition to the known benefits of induction, there is no increased risk of severe perineal lacerations.

Keywords: 3rd-degree laceration; 4th-degree laceration; OASIS; induction of labor; severe perineal laceration; vaginal delivery.