Predicting Cesarean Delivery After Induction of Labor Among Nulliparous Women at Term

Using the Probability of Cesarean from a Validated Cesarean Prediction Calculator to Predict Labor Length and Morbidity

OBJECTIVE

To determine if increasing predicted risk of cesarean was associated with longer labor length and increased morbidity among women undergoing induction with an unfavorable cervix.

STUDY DESIGN

Using a publically available database, we evaluated whether a previously validated prediction model for cesarean delivery after induction was associated with labor length, maternal morbidity (third-/fourth-degree lacerations, endometritis, blood transfusion, wound infection, venous thromboembolism, hysterectomy, intensive care unit admission, and death), and neonatal morbidity (blood transfusion, encephalopathy, intraventricular hemorrhage, severe respiratory distress syndrome, necrotizing enterocolitis, and sepsis). Full-term (≥37 weeks) singleton gestations with intact membranes and an unfavorable cervix (Bishop score ≤6 and dilation ≤2 cm) undergoing induction of labor were included.

RESULTS

A total of 8,466 women met the inclusion criteria. Each category increase in cesarean probability (<20, 20-39.9, 40-59.9, ≥60%) was associated with an increase in labor length (9.6, 10.8, 11.7, and 11.9 hours, respectively; p < 0.001). With increasing predicted probability of cesarean there, was also a significant increase in maternal morbidity with each category (2.6, 4.7, 5.1, 6.1%; p = 0.001) and increase in neonatal morbidity (0.9, 1.5, 2, 2.2%; p = 0.002).

CONCLUSION

Using a validated prediction model for cesarean delivery among women induced with an unfavorable cervix, increasing predicted probability of cesarean is associated with longer labor length and increased maternal and neonatal morbidity.

Combining Spinal-Epidural Anesthesia versus Single-Shot Spinal Anesthesia for Cesarean Delivery: A Meta-Analysis of 5 Randomized Controlled Trials

Background

This study compared combined spinal-epidural anesthesia (CSEA) and single-shot spinal anesthesia (SSSA) by performing a meta-analysis.

Material/Methods

An electronic search of relevant studies was done through 2017. Primary endpoints included duration of surgery, and time for (1) sensory recovery to thoracic vertebra (T10), (2) maximal sensory, (3) motor blockade, and (4) motor recovery. Secondary endpoints were the adverse effects. RevMan 5.3 analytical software was used with odds ratios (OR) and 95% confidence intervals (CIs) as the analytic parameters. Standard deviation and mean were used to evaluate data by weighted mean differences (WMDs) with 95% CI.

Results

A total of 370 patients were analyzed. A similar duration of surgery was observed with CSEA and SSSA (WMD: 0.24, 95%CI: −3.41–3.89; P=0.90). Time to maximal sensory blockade (WMD: 0.96, 95%CI: −2.91–4.83), time to maximal motor blockade (WMD: 0.25, 95%CI: −2.46–2.96), time for complete motor recovery (WMD: −6.28, 95%CI: −29.42–16.86), and time for sensory recovery to T10 vertebra (WMD: 0.42, 95%CI: −11.07–11.91) were not significantly different. Adverse effects such as hypotension (OR: 1.49, 95%CI: 0.27–8.31), pruritus (OR: 0.23, 95%CI: 0.03–2.18), nausea/vomiting (OR: 0.84, 95%CI: 0.12–5.99). and shivering (OR: 0.53, 95%CI: 0.11–2.56) were also similar with CSEA and SSSA.

Conclusions

CSEA was not associated with significantly different maximal duration of sensory/motor blockade, complete motor recovery, sensory regression to T10, or adverse drug events compared to SSSA. Hence, both should be considered effective in cesarean delivery.

Prediction models for determining the success of labor induction: A systematic review

INTRODUCTION

The purpose of this study was to systematically identify and compare clinical models using universally accessible clinical and demographic factors that were derived and/or validated to predict the success of labor induction with a view to making recommendations for practice.

MATERIAL AND METHODS

MEDLINE, Embase, www.clinicaltrials.gov, and PubMed (for non-MEDLINE and studies in-progress) were searched from inception to November 2017. Only studies that derived and/or validated clinical prediction models using variables obtained through antenatal history and digital cervical examination were included. Two reviewers independently screened titles and abstracts and extracted data from eligible studies into a standardized form. Extracted data included: participant characteristics, sample size, variables considered and included, endpoint definitions, study design and model performance. The Prediction Study Risk of Bias Assessment Tool (PROBAST) was used to appraise included studies. In view of clinical and methodologic heterogeneity between studies, only descriptive analysis was possible. The protocol was registered with the PROSPERO International prospective register of systematic reviews [CRD42017081548].

RESULTS

The search identified 16 studies describing 14 prediction models derived between 1966 and 2018. Models varied and demonstrated major limitations with regard to methodology, scope and performance. Of the derived models, six were internally validated and three were externally validated. Performance was most commonly measured using the area under the receiver operator characteristic curve, which ranged from 0.68 to 0.79, 0.67 to 0.77 and 0.61 to 0.73 for derived, internally validated and externally validated models, respectively. The risk-of-bias of included studies ranged from some studies fulfilling only 36% and some others fulfilling 86% of eligible PROBAST items.

CONCLUSIONS

No published model can be recommended for use at the bedside to determine the success of vaginal birth after labor induction. Based on the limitations of included models, a list of recommendations for improving model performance and utilization is provided, as well as measures for encouraging appropriate use of prediction models. The attitudes of women and care providers, and the clinical and resource implications must be explored prior to recommending the use of prediction models for determining the success of labor induction.

"Doing something" about the cesarean delivery rate

There is a general consensus that the cesarean delivery rate in the United States is too high, and that practice patterns of obstetricians are largely to blame for this situation. In reality, the US cesarean delivery rate is the result of 3 forces largely beyond the control of the practicing clinician: patient expectations and misconceptions regarding the safety of labor, the medical-legal system, and limitations in technology. Efforts to "do something" about the cesarean delivery rate by promulgating practice directives that are marginally evidence-based or influenced by social pressures are both ineffective and potentially harmful. We examine both the recent American Congress of Obstetricians and Gynecologists (ACOG)/Society for Maternal-Fetal Medicine Care Consensus Statement "Safe Prevention of Primary Cesarean Delivery" document and the various iterations of the ACOG guidelines for vaginal birth after cesarean delivery in this context. Adherence to arbitrary time limits for active phase or second-stage arrest without incorporating other clinical factors into the decision-making process is unwise. In a similar manner, ever-changing practice standards for vaginal birth after cesarean driven by factors other than changing data are unlikely to be effective in lowering the cesarean delivery rate. Whether too high or too low, the current US cesarean delivery rate is the expected result of the unique demographic, geographic, and social forces driving it and is unlikely to change significantly given the limitations of current technology to otherwise satisfy the demands of these forces.

A validated calculator to estimate risk of cesarean after an induction of labor with an unfavorable cervix

BACKGROUND

Induction of labor occurs in >20% of pregnancies, which equates to approximately 1 million women undergoing an induction in the United States annually. Regardless of how common inductions are, our ability to predict induction success is limited. Although multiple risk factors for a failed induction have been identified, risk factors alone are not enough to quantify an actual risk of cesarean for an individual woman undergoing a cesarean.

OBJECTIVE

The objective of this study was to derive and validate a prediction model for cesarean after induction with an unfavorable cervix and to create a Web-based calculator to assist in patient counseling.

STUDY DESIGN

Derivation and validation of a prediction model for cesarean delivery after induction was performed as part of a planned secondary analysis of a large randomized trial. A predictive model for cesarean delivery was derived using multivariable logistic regression from a large randomized trial on induction methods (n = 491) that took place from 2013 through 2015 at an academic institution. Full-term (≥37 weeks) women carrying a singleton gestation with intact membranes and an unfavorable cervix (Bishop score ≤6 and dilation ≤2 cm) undergoing an induction were included in this trial. Both nulliparous and multiparous women were included. Women with a prior cesarean were excluded. Refinement of the prediction model was performed using an observational cohort of women from the same institution who underwent an induction (n = 364) during the trial period. An external validation was performed utilizing a publicly available database (Consortium for Safe Labor) that includes information for >200,000 deliveries from 19 hospitals across the United States from 2002 through 2008. After applying the same inclusion and exclusion criteria utilized in the derivation cohort, a total of 8466 women remained for analysis. The discriminative power of each model was assessed using a bootstrap, bias-corrected area under the curve.

RESULTS

The cesarean delivery rates in the derivation and external validation groups were: 27.7% (n = 136/491) and 26.4% (n = 2235/8466). In multivariable modeling, nulliparity, gestation age ≥40 weeks, body mass index at delivery, modified Bishop score, and height were significantly associated with cesarean. A nomogram and calculator were created and found to have an area under the curve in the external validation cohort of 0.73 (95% confidence interval, 0.72-0.74).

CONCLUSION

A nomogram and user-friendly Web-based calculator that incorporates 5 variables known at the start of induction has been developed and validated. It can be found at: http://www.uphs.upenn.edu/obgyn/labor-induction-calculator/. This calculator can be used to augment patient counseling for women undergoing an induction with an unfavorable cervix.

Cervical dilation balloon combined with intravenous drip of oxytocin for induction of term labor: a multicenter clinical trial

OBJECTIVE

This study aimed to investigate the effectiveness and safety of a method combining double-balloon catheter for cervical ripening and intravenous drip of oxytocin on the induction of term labor, providing the reference for clinical safety.

METHODS

A total of 120 pregnant women with a gestation between 37⁺⁰ and  41⁺⁶ weeks, indications of labor induction, singleton pregnancy with cephalic presentation were enrolled. The patients were divided into the research group receiving cervical dilation balloon combined with intravenous drip of oxytocin and the control group receiving an intravenous drip of oxytocin at a concentration of 0.5% for labor induction (n = 60 for each). The effectiveness and safety of labor induction were evaluated by the rates of successful cervical ripening promotion and labor induction, as well as the vaginal delivery rate, induced labor time, total duration of labor, the total amount of postpartum hemorrhage within 24 h after giving birth, the incidences of postpartum hemorrhage, cervical laceration, puerperal infection and neonatal outcomes.

RESULTS

There was no statistical difference in the basal demographic and clinical characteristics, including ages, gestational weeks, delivery times and Bishop scores at admission between two groups. The rate of successful cervical ripening promotion (research vs. control = 90.00% vs. 55.00%), the rate of successful induction (95.00% vs. 40.00%), the vaginal delivery rate (93.33% vs. 63.33%), the induced labor time (15.03 ± 5.40 vs. 30.68 ± 10.82 h), and the total duration of labor (8.12 ± 2.65 vs. 15.01 ± 6.06 h) were significantly different between two groups (all P < 0.05). There was no significant difference in the total amount of postpartum hemorrhage, incidences of postpartum hemorrhage, cervical laceration, puerperal infection as well as the neonatal outcomes, including neonatal weight, neonatal asphyxia and incidence of meconium aspiration syndrome between two groups.

CONCLUSIONS

Compared to labor induction of oxytocin, the method combining double-balloon catheter for cervical ripening and intravenous drip of oxytocin for the induction of term labor has a higher vaginal delivery rate, shorter total duration of labor, and does not increase the incidences of postpartum hemorrhage and neonatal infection, which is a more effective and safer method for induction of term labor.

Labor induction and cesarean delivery: A prospective cohort study of first births in Pennsylvania, USA

BACKGROUND

Mode of delivery at first childbirth largely determines mode of delivery at subsequent births, so it is particularly important to understand risk factors for cesarean delivery at first childbirth. In this study, we investigated risk factors for cesarean delivery among nulliparous women, with focus on the association between labor induction and cesarean delivery.

METHODS

A prospective cohort study of 2851 nulliparous women with singleton pregnancies who attempted vaginal delivery at hospitals in Pennsylvania, 2009-2011, was conducted. We used nested logistic regression models and multiple mediational analyses to investigate the role of three groups of variables in explaining the association between labor induction and unplanned cesarean delivery-the confounders of maternal characteristics and indications for induction, and the mediating (intrapartum) factors-including cervical dilatation, labor augmentation, epidural analgesia, dysfunctional labor, dystocia, fetal intolerance of labor, and maternal request of cesarean during labor.

RESULTS

More than a third of the women were induced (34.3%) and 24.8% underwent cesarean delivery. Induced women were more likely to deliver by cesarean (35.9%) than women in spontaneous labor (18.9%), unadjusted OR 2.35 (95% CI 1.97-2.79). The intrapartum factors significantly mediated the association between labor induction and cesarean delivery (explaining 76.7% of this association), particularly cervical dilatation <3 cm at hospital admission, fetal intolerance of labor, and dystocia. The indications for labor induction only explained 6.2%.

CONCLUSIONS

Increased risk of cesarean delivery after labor induction among nulliparous women is attributable mainly to lower cervical dilatation at hospital admission and higher rates of labor complications.

A randomized trial of Foley balloon induction of labor trial in nulliparas (FIAT-N)

BACKGROUND

With an increasing rate of induction of labor, it is important to choose induction methods that are safe and efficient in achieving a vaginal delivery. The optimal method for inducing nulliparous women with an unfavorable cervix is not known.

OBJECTIVE

We sought to determine if induction of labor with simultaneous use of oxytocin and Foley balloon vs sequential use of Foley balloon followed by oxytocin decreases the time to delivery in nulliparous women.

STUDY DESIGN

We conducted a randomized controlled trial of nulliparous women presenting for induction at a single institution from December 2013 through March 2015. After decision for induction was made by their primary provider, women with gestational age ≥24 weeks with a nonanomalous, singleton fetus in vertex presentation with intact membranes were offered participation. Exclusion criteria included history of uterine surgery, unexplained vaginal bleeding, latex allergy, or contraindication to vaginal delivery. Participants were randomized to either simultaneous (oxytocin and Foley balloon) or sequential (oxytocin after expulsion of Foley balloon) induction group. The primary outcome was time from induction to delivery. Secondary outcomes included mode of delivery, estimated blood loss, postpartum hemorrhage, chorioamnionitis, and composite neonatal outcome. Maternal and neonatal outcomes were collected via chart review. Analyses were done on an intention-to-treat basis.

RESULTS

A total of 166 patients were enrolled; 82 in the simultaneous and 84 in the sequential group. There were no differences in baseline characteristics in the 2 groups. Patients who received simultaneous oxytocin with insertion of a Foley balloon delivered significantly earlier (15.92 vs 18.87 hours, P = .004) than those in the sequential group. There was no difference in rate of cesarean delivery, estimated blood loss, postpartum hemorrhage, chorioamnionitis, or composite neonatal outcome.

CONCLUSION

Simultaneous use of oxytocin and Foley balloon for induction of labor results in a significantly shorter interval to delivery in nulliparas.