Induction of labor in women that had a previous cesarean delivery

Retrospective evaluation of labor induction with scar uterus at the university hospital of Rennes

OBJECTIVE

The aim of the study was a retrospective evaluation of labor induction in women with one previous cesarean section. The primary outcome was the mode of delivery. We also studied the severe maternal and neonatal morbidity and identify some prediction factors of vaginal delivery after labor induction after one previous cesarean section.

STUDY DESIGN

This was a retrospective observational monocentric study performed over the period from January 1st, 2016 to April 30th, 2020 at the university hospital of Rennes. Were included women with scar uterus because of one previous cesarean section with a viable singleton fetus in cephalic presentation and an induction of labor for medical reason, at term. Multivariate logistic regression analysis was used to analyze prediction of vaginal delivery after labor induction after one previous cesarean section. We also studied maternal (included uterine rupture, loss of blood, obstetrical injury of anus sphincter) and neonatal (APGAR score, arterial umbilical pH after 1 minute of life and eventual admission to neonatal unit) morbidity. We used a stepwise multivariate logistic regression model to select variables for multivariate analysis. The model with the lowest Akaike Index Criteria was chosen.

RESULTS

The study enrolled 353 women with scar uterus: 121 women were induced by balloon catheter, 57 by osmotic cervical dilatators, 91 by oxytocin alone, 84 by amniotomy. Vaginal delivery rate was 47,9%. There was 45% of vaginal delivery in the group with Bishop < 6 before induction of labor versus 62% in the group with Bishop ≥ 6. There was no statistically significative difference in neonatal and maternal severe morbidities between vaginal delivery and cesarean section: 4,5% of severe maternal morbidities (n = 16). Among their, we highlighted 7 uterine ruptures (3,8%). We observed also 3% of postpartum severe hemorrhage in vaginal delivery group (n = 5) against 1,6% in cesarian section group (n = 3) with no statistical significant difference (p = 0,632). Regarding to the obstetric perineal tears and lacerations we noticed 1,2% of OASIS 3 (n = 2) and 0,6% of OASIS 4 (n = 1). Severe neonatal morbidities were comparable by mode of delivery without significant difference: APGAR score at 5 min was similar (p = 1), as well as arterial umbilical pH after 1 min. (p = 0.719) and admissions to a neonatal unit (p = 1). Two variables were statistically associated with vaginal delivery after labor induction in women with scar uterus: Bishop score ≥ 6 (OR = 0,44; 95%CI: 0,25-0,81) and/or previous vaginal delivery after cesarean section (OR = 0,17; 95%CI: 0,08-0,35).

CONCLUSION

With 47,9% of vaginal delivery after labor induction in women with scar uterus, only 3.8% (n = 7/353) of uterine ruptures, less than 1% APGAR < 7 at 5 min (n = 3/353), induction on scar uterus should be consider in obstetrical practice. Bishop score ≥ 6 and/or previous vaginal delivery after cesarean section are associated to vaginal delivery after labor induction.

Oxytocin use in trial of labor after cesarean and its relationship with risk of uterine rupture in women with one previous cesarean section: a meta-analysis of observational studies

BACKGROUND

Trial of labor after a previous cesarean delivery (TOLAC) has reduced the rate of cesarean sections (CS). Nevertheless, the widespread use of TOLAC has been limited by an increase in adverse outcomes, the most serious one being the risk of symptomatic uterine rupture, which is possibly associated with oxytocin. In this meta-analysis, we explored the risk association between oxytocin use and uterine rupture in TOLAC.

METHODS

Multiple electronic databases (PubMed, Embase, Web of Science, and Google Scholar) were searched for cross-sectional studies reporting on TOLAC, oxytocin and uterine rupture, which were published between January 1986 and October 2019. The bias-corrected Hedge's g was calculated as the effect size using the random-effects model. A two-sample Z test was used to compare the differences in synthetic rates between groups. The Newcastle-Ottawa Scale (NOS) was used to evaluate the risk of bias. Quality of the evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) certainty ratings system.

RESULTS

A total of 14 studies, which included 48,457 women who underwent TOLAC, met the inclusion criteria. The pooled rate of vaginal birth after a cesarean section (VBAC) and the rate of uterine rupture in spontaneous labor were 74.3 and 0.7%, respectively. In addition, the pooled rate of VBAC and the rate of uterine rupture in the induction labor group was 60.7 and 2.2%, respectively. The women who had spontaneous labor had a significantly higher rate of VBAC (p = 0.001) and a lower rate of uterine rupture (p = 0.0003) compared to induced labor. The pooled rates of uterine rupture in women using oxytocin and women not using oxytocin in TOLAC were 1.4% and 0.5%, respectively, and the difference was significant (p = 0.0002). Also, the synthetic rate of uterine rupture in oxytocin augmentation among women with spontaneous labor and women who had a successful induction of labor were 1.7% and 2.2%, respectively, without significant difference (p = 0.443).

CONCLUSIONS

Women with induced labor had a higher risk of uterine rupture compared to women with spontaneous labor following TOLAC. Oxytocin use may increase this risk, which could be influenced by the process of induction or individual cervix condition. Consequently, simplified and standardized intrapartum management, precise protocol, and cautious monitoring of oxytocin use in TOLAC are necessary.

Factors associated with successful vaginal birth after a cesarean section: a systematic review and meta-analysis

Background

Evidence for the relationship between maternal and perinatal factors and the success of vaginal birth after cesarean section (VBAC) is conflicting. We aimed to systematically analyze published data on maternal and fetal factors for successful VBAC.

Methods

A comprehensive search of Medline, Embase, and the Cumulative Index to Nursing and Allied Health Literature, from each database’s inception to March 16, 2018. Observational studies, identifying women with a trial of labor after one previous low-transverse cesarean section were included. Two reviewers independently abstracted the data. Meta-analysis was performed using the random-effects model. Risk of bias was assessed by the Newcastle-Ottawa Scale.

Results

We included 94 eligible observational studies (239,006 pregnant women with 163,502 VBAC). Factors were associated with successful VBAC with the following odds ratios (OR;95%CI): age (0.92;0.86–0.98), obesity (0.50;0.39–0.64), diabetes (0.50;0.42–0.60), hypertensive disorders complicating pregnancy (HDCP) (0.54;0.44–0.67), Bishop score (3.77;2.17–6.53), labor induction (0.58;0.50–0.67), macrosomia (0.56;0.50–0.64), white race (1.39;1.26–1.54), previous vaginal birth before cesarean section (3.14;2.62–3.77), previous VBAC (4.71;4.33–5.12), the indications for the previous cesarean section (cephalopelvic disproportion (0.54;0.36–0.80), dystocia or failure to progress (0.54;0.41–0.70), failed induction (0.56;0.37–0.85), and fetal malpresentation (1.66;1.38–2.01)). Adjusted ORs were similar.

Conclusions

Diabetes, HDCP, Bishop score, labor induction, macrosomia, age, obesity, previous vaginal birth, and the indications for the previous CS should be considered as the factors affecting the success of VBAC.