Comparison of digital and ultrasonographic examination of the cervix in predicting time interval from induction to delivery in women with a low Bishop score

Comparing Pre-Induction Ultrasound Parameters and the Bishop Score to Determine Whether Labor Induction Is Successful

Background and Objectives: The incidence of labor induction is steadily increasing worldwide. The main aim of this study was to evaluate the ultrasound parameters and their mutual correlation and to analyze the parameters' predictive capability in assessing the success of labor induction. The secondary goal was to assess patients' tolerability and acceptance of transvaginal ultrasound and digital gynecological examination. Materials and Methods: This prospective observational follow-up study included 252 women selected for labor induction. The transvaginal ultrasound examination measured the posterior cervical angle, cervical length, the length and width funneling of the cervix, the distance between the head of the fetus and the external uterine os, and the position of the fetal occiput. After the ultrasound, a digital vaginal examination was performed (according to the Bishop score), and the women were asked to rate their perception of pain for each procedure. Results: The most common indication for labor induction was post-term pregnancy (57.59%), and the most common method of labor induction was oxytocin with amniotomy (70%). The results showed that a significant independent prediction of vaginal delivery could be provided based on the Bishop score and cervical length. Other investigated ultrasound parameters, the length and width of the funneling of the cervix (p < 0.001), the fetal head stage (p < 0.001), and the size of the posterior cervical angle (p < 0.05), showed statistical significance in relation to the success of labor induction. Patients reported lower discomfort and pain during transvaginal ultrasound examination (mean score 2, IQR 3) compared to digital examination (mean score 5, IQR 4), with p < 0.001. Conclusions: The results imply that the assessment of ultrasound parameters before induction of labor is necessary to predict the outcome and reduce the possibility of complications. In terms of tolerability and choice by the patients, the transvaginal ultrasound examination was better rated than the vaginal gynecological examination.

Reliability and Reproducibility of Analyzing 3D Transperineal Ultrasound Volumes Obtained in the First Phase of Labor - A Pilot Study

PURPOSE

The aim of this study was to investigate the reliability and reproducibility of transperineal ultrasound (TPUS) in the initial phase of labor. As TPUS is a common method, it could supplement vaginal palpation and even replace it in certain situations. In addition, we used a 4-dimensional method for the assessment of cervical effacement.

MATERIALS AND METHODS

54 women in labor were included and underwent TPUS. The resulting images from the acquired 4D volumes were evaluated after the examination for the first time and a second time after 21 days. The measured values were cervical length, dilatation and effacement, the angle of progression (AoP), and head-perineum distance.

RESULTS

54 patients were examined. TPUS images were unable to be evaluated in 12 patients because of cervical dilatation of more than 5 cm or poor image quality. Thus, 42 measurements were included. The concordance correlation coefficients according to Lin are satisfactory overall, with one exception for cervical effacement. The accuracy component of cervical length (CCCLin: 0.93; accuracy: 1.00), dilatation (CCCLin: 0.93; accuracy: 1.00), and AoP (CCCLin: 0.87; accuracy: 1.00) is excellent and still high for the head-perineum distance (CCCLin: 0.89; accuracy: 0.96) and cervical effacement (CCCLin: 0.77; accuracy: 0.97).

CONCLUSION

TPUS is a valuable noninvasive tool with good diagnostic accuracy for the AoP, cervical length, and dilatation. Our study provides support for the use of TPUS to complement a vaginal examination. It should not replace a digital examination but should serve as a suitable alternative method for monitoring labor progression in the future.

An analysis of misoprostol effectiveness in second trimester pregnancy terminations

Background/Aim: Misoprostol is frequently used as a single agent in pregnancy terminations. However, it increases the risk of uterine rupture in patients who have had previous uterine surgery and terminations due to stillbirths. Therefore, it is used with concern by clinicians. The aim of this study was to evaluate the clinical features of the groups that responded and did not respond to termination treatment with misoprostol in a tertiary center and to investigate its efficacy and safety. Methods: The study design was comprised of a retrospective cohort study. A total of 114 second trimester pregnancies (between 13-24 weeks gestational age) were included in the study. These pregnancies were indicated for termination based on the prenatal diagnosis unit for fetal or maternal causes. According to the International Federation of Gynecology and Obstetrics (FIGO) directions, misoprostol was applied in the following dosages: for 13-17 weeks gestational ages, one tablet per 6 hours; for 18-26 gestational ages, ½ tablet per 6 hours; and for other indications 2 tablets per 3 hours were administered. If the patient had had a previous cesarean operation, all doses were halved. After the first 24 hours, the percentage and demographics results, such as age, body mass index (BMI), gravida, number of cesareans, number of curettages, cervical lengths, BISHOP scores, gestational age, amniotic fluid index, and fetal cardiac beat of the patients with miscarriage, were recorded. Results: The number of cases resulting in miscarriage within 24 hours were 84 (73.7%) and within 48 hours were 14 (12.2%). The total of misoprostol doses used were 8 tablets of 200 mg, mean time until the complete abortion was 17 hours. Sixteen patients required additional treatment, of whom four required Foley catheterization, five required D&E, seven required resting, and no one required a hysterectomy. Uterine rupture occurred in two patients who needed laparotomic surgery. The maternal age (P=0.340), BMI (P=0.790), gravida (P=0.270), previous cesarean history (P=0.390), previous curettage number (P=0.520), cervical length (P=0.380), Bishop score (P=0.190), gestational age (P=0.072), amniotic fluid index (P=0.470) and presence of fetal cardiac beat (P=0.350) were similar between groups Conclusion: Our results indicated that misoprostol is a safe, useful, and effective treatment option for second trimester medical terminations. Caution should be exercised in its use in patients with a history of uterine surgery.

Predictive factors for vaginal delivery by induction of labor in uncomplicated pregnancies at 40-41 gestational weeks: A Japanese prospective single-center cohort study

AIM

We investigated cervical parameters predictive of vaginal delivery in elective labor induction among women at 40-41 gestational weeks.

METHODS

This Japanese prospective single-center cohort study was conducted between July 2019 and June 2020. We enrolled women with an uncomplicated singleton pregnancy who underwent labor induction at 40-41 gestational weeks. We analyzed background characteristics and cervical parameters, including Bishop score, cervical length, posterior cervical angle, and changes in cervical parameters before and after cervical dilatation. The endpoint was the rate of vaginal delivery.

RESULTS

Of 142 eligible participants, all 24 multiparous women underwent vaginal delivery. Among the nulliparous women (n = 118), the following categories showed significantly higher rates of vaginal delivery: Bishop scores of ≥6 before and after dilatation, compared with Bishop score <6 (adjusted prevalence ratio (aPR) [95% confidence interval (CI)]; 1.58 [1.17-2.13] and 1.56 [1.13-2.14], respectively) and cervical length of <10 and 10-20 mm before dilation, compared with cervical length of >30 mm (aPR [95% CI]; 1.47 [1.00-2.15] and 2.13 [1.42-3.18], respectively). The posterior cervical angle and other background characteristics showed no significant associations. Furthermore, women with cervical lengths of ≥20 mm before and <20 mm after dilatation showed a higher rate of vaginal delivery, compared to cervical length of ≥20 mm even after dilatation (aPR [95% CI]; 1.95 [1.19-3.20]).

CONCLUSIONS

High Bishop score, short cervical length, and changes in cervical length with dilatation are potential independent predictors of vaginal delivery following elective labor induction in nulliparous women at 40-41 gestational weeks.

The use of ultrasound, fibronectin and other parameters to predict the success of labour induction

Induction of labour is a common obstetrical procedure and is undertaken when the benefits of delivery are considered to outweigh the risks of continuation of pregnancy. However, more than one-fifth of induction cases fail to result in vaginal births and lead to unplanned caesarean deliveries, which compromise the birth experience and have negative clinical and resource implications. The need for accurate prediction of successful labour induction is increasingly recognised and many researchers have attempted to evaluate the potential predictability of different factors including maternal characteristics, Bishop score, various biochemical markers and ultrasound markers and derive predictive models to address this issue.

The Value of Posterior Cervical Angle as a Predictor of Vaginal Delivery: A Preliminary Study

Accurate prediction of failure to progress and rapid decision making regarding the mode of delivery can improve pregnancy outcomes. We examined the value of sonographic cervical markers in the prediction of successful vaginal delivery beyond 34 weeks of gestation. A retrospective chart review was carried out. Medical information of singleton gestations delivered at a single center from 1 July 2019 to 30 August 2020 was collected. Transvaginal sonographic records of cervical length, anterior and posterior cervical angles, and cervical dilatation were obtained and re-measured. The value of these markers and clinical characteristics of mother and baby on vaginal delivery were investigated and compared to women who underwent cesarean section. A total of 90 women met the inclusion criteria. The rate of vaginal delivery was 75.6%. There were no differences found in terms of maternal age, rate of abortion, induction of labor, premature rupture of membranes, preterm labor, hypertension, diabetes, cervical length, and neonatal sex and weight. The prediction of vaginal delivery was provided by parity, maternal body mass index, and posterior cervical angle. The area under the receiver operating characteristic curve for prediction of vaginal delivery was 0.667 (95% CI 0.581–0.864, p = 0.017) for the posterior cervical angle, with a cutoff of 96.5°. Regression analysis revealed a posterior cervical angle ≥96.5° in the prediction of vaginal delivery (adjusted odds ratio: 6.24; 95% confidence interval: 1.925–20.230, p = 0.002). Posterior cervical angle ≥96.5° is associated with successful vaginal delivery. It is simple and easy to measure and can be useful in determining the mode of delivery.

Towards an evidence-based approach to optimize the success of labour induction

Induction of labour is a two-step process involving cervical ripening and the initiation of uterine contractions, with the goal of achieving vaginal birth. To optimize the chance of a safe and timely vaginal birth, the process of induction of labour should be evidence based and individualized to the given person and situation. In this study, we lay out a framework for how this should be done, emphasizing on careful clinical assessment and planning, flexibility in the strategy of induction, patience during the ripening and latent phases of labour, and thoughtful consideration regarding changing the strategy if active labour is not initially achieved. The goal of this review is to present the current evidence on this topic in the form of a user-friendly protocol that can be easily adapted to institutional practice.

Contribution of ultrasonography to the prediction of the induction-delivery interval: The ECOLDIA prospective multicenter cohort study

INTRODUCTION

To evaluate the ability of preinduction ultrasonographic cervical length to predict the interval between induction and delivery in women at term with a Bishop score of 4 to 6 at induction.

STUDY DESIGN

This multicenter prospective observational cohort recruited 334 women from April 2010 to March 2014. Inclusion criteria were women with singleton pregnancies at a gestational age ≥37 weeks, with no previous caesarean, a medical indication for induction of labor, and a Bishop score of 4, 5, or 6. All women underwent cervical assessment by both transvaginal ultrasound and digital examination (Bishop score). The induction protocol was standardized. The primary outcome measure was the induction-delivery interval. Hazard ratios (HR) and their 95% confidence intervals (95% CI) were used to assess potential predictors.

RESULTS

Mean gestational age at induction was 40.1 weeks, 60.8% of the women were nulliparous, and the cesarean rate was 13.4%. The mean induction-delivery interval was 20.8 h (± 10.6). Delivery occurred within 24 h for 56.9% (n=190) of the women. An ultrasonographic cervical length measurement less than 25 mm (HR=1.50, 95% CI 1.18-1.91, P<0.01) and parity (HR=1.41, 95% CI 1.21-1.65, P<0.01) appeared to predict induction-delivery interval. The cervical length cutoff to reduce the induction-delivery interval was 25 mm.

CONCLUSION

A cervical length cutoff of 25 mm was associated with shorter induction-delivery interval in women at term with a Bishop score of 4 to 6.

Sonographic measurement of cervical length and head perineum distance before labor to predict time of delivery

OBJECTIVES

This was an observational study on cervical length and head perineum distance and the prediction of time of delivery. One-hundred and twenty-five nulliparous women with uncomplicated, term, singleton pregnancy were recruited when they presented to the labor ward with show or infrequent painful uterine contractions (less than three contractions in ten minutes on a 30 min cardiotocogram). Apart from digital vaginal examination to assess cervical length and dilatation, sonographic cervical length and head perineum distance were measured by two-dimensional ultrasound. We compared women who delivered within 72 h of presentation of labor symptoms, with women who did not. After excluding ten women whose labor was induced and delivered within 72 h of presentation, one hundred and fifteen women were included for final data analysis.

MAIN FINDINGS

Forty-nine women (42.6%) delivered while sixty-six women (57.4%) remained undelivered at 72 h of presentation of symptoms of labor. There was no statistically significant difference between the two groups on age, presence of show, contractions, fetal head station and presentation and mode of delivery. For the group who had delivered within 72 h of presentation of labor symptoms, the mean sonographic cervical length was 1.87 cm ± 0.62 cm, while the head perineum distance was 6.01 cm ± 1.15 cm. For the other group, the mean sonographic cervical length was 2.10 cm ± 0.83 cm; head perineum distance was 6.03 cm ± 1.18 cm. There was no statistically significant difference between the groups for both sonographic cervical length (p = .90); and head perineum distance (p = .08). We also compared the cervical length measured by digital vaginal examination versus sonography. The median sonographic measurements were 1.47 cm, 2.11 cm and 2.79 cm at "1 cm," "2 cm" and "3 cm" digital vaginal measurement, respectively. However, there was extensive overlap between digitally and sonographically measured cervical length. Prediction accuracy of cervical length and head perineum distance was poor. The area under curve (AUC) of receiver operating characteristic (ROC) curve were 0.433 for sonographic cervical length and 0.501 for HPD.

CONCLUSION

Transperineal sonographical assessment of cervical length and head perineum distance before labor was not useful in predicting the time of delivery. However, it can be explored as an alternative assessment method when digital vaginal examination is not preferred.

Clinical and ultrasonographic parameters in assessment of labor induction success in nulliparous women

Purpose: Evaluation of simplified Bishop score and ultrasound cervicometry in the assessment of labor induction success in nulliparous women.Methods: Prospective cohort study included 146 nulliparous women with singleton pregnancy and indications for labor induction. Prior to labor induction, cervicometry and Bishop score were determined. Upon delivery, patients were classified as those delivered vaginally and by cesarean section (CS) after unsuccessful labor induction.Results: Bishop score >5 was found in 47.95% of vaginally delivered women and 12.33% of patients delivered by CS (p < .01). Cervicometry had appropriate findings in 34.2% of vaginally delivered women and 75.3% of those delivered by CS (p < .01). Bishop score (>5 versus ≤5) had lower sensitivity (52.05%) and specificity (12.33%) than cervicometry (good versus unfavorable findings) (sensitivity 65.75%, specificity 75.34%) for prediction of labor induction success. If Bishop score was ≤5, cervicometry had 50.0% sensitivity and 78.13% specificity, while if Bishop score was >5, 82.86% sensitivity and 55.56% specificity. Obtained model for predicting labor induction outcome in nulliparous women based on their clinical and ultrasonographical characteristics identified the Bishop score as the most important predictor.Conclusions: Study confirmed the usefulness of simplified Bishop score and ultrasound cervicometry in the assessment of labor induction success in nulliparous women.

Transvaginal sonographic measurement of cervical length versus Bishop score in labor induction at term for prediction of caesarean delivery

OBJECTIVE

The current study aims to compare between a transvaginal sonographic measurement of cervical length and Bishop score in the induction of labor (IOL) at term for prediction of cesarean delivery (CD).

MATERIALS AND METHODS

A prospective cohort study included 320 full-term pregnant women attending Ain Shams Maternity Hospital in the period from August 2017 to February 2018 were enrolled. Seventy-three women were delivered by CD (positive group), and 247 women were delivered vaginally (negative group). All patients had a vaginal examination for assessing the Bishop Score before IOL then a transvaginal ultrasound for assessment of cervical length. IOL was initiated by using PGE1 analog. The primary outcome measure was the accuracy of the cervical length or the bishop score for prediction of the CD.

RESULTS

In our current study, CD was achieved in 22.8% of all participants while vaginal delivery was achieved in 77.8% after IOL by misoprostol 25 micrograms within 24 h from the beginning of induction. Both the cervical length and Bishop Score had poor predictive value for CD (AUC = 0.694 and 0.623, respectively).

CONCLUSIONS

Both transvaginal sonography for cervical length and Bishop score are useful predictors of the need for CD following labor induction.

Prediction of the induction to delivery time interval in vaginal dinoprostone-induced labor: a retrospective study in a Chinese tertiary maternity hospital

Objective

This study aimed to investigate the potential factors that affect the induction to delivery time interval in women undergoing induction of labor with a controlled-release dinoprostone vaginal insert.

Methods

Pregnant women who presented for delivery at Hubei Maternal and Child Health Hospital from January 2016 to August 2016 were recruited. Finally, 1265 women who underwent labor induction with a vaginal dinoprostone (PGE2) insert were analyzed. Univariate and multivariate linear regression analyses were used to estimate the relevant risks for delivery time.

Results

Among the1265 subjects, the mean delivery time was 18.92 ± 12.50 hours. Univariate and multivariate analyses showed that fetal weight, an obstetric complication (premature rupture of the membranes), and the delivery history were significantly associated with the induction to delivery time. Biparietal diameter was related to the vaginal delivery time in univariate analysis, but there was no significant difference after adjustment in multivariate analysis.

Conclusions

Vaginal dinoprostone is an effective method for successful induction of labor. Gestational age, parity, and fetal weight are major factors that predict the induction to delivery time interval.

Ultrasound cervical length measurement in prediction of labor induction outcome

Induction of labor is one of the most common procedures in modern obstetrics, with an incidence of approximately 20% of all deliveries. Not all of these inductions result in vaginal delivery; some lead to cesarean sections, either for emergency reasons or for failed induction. That's why, It seems necessary to outline strategies for the improvement of the success rate of induced deliveries. Traditionally, the identification of women in whom labor induction is more likely to be successful is based on the Bishop score. However, several studies have shown it to be subjective, with high variation and a poor predictor of the outcome of labor induction. Transvaginal sonography for cervical measurement can be a more objective criterion in assessing the success of labor induction. Many studies have been done recently to compare cervical measurement and Bishop Score in labor induction.This paper reviewed the literature that evaluated sonographic cervical length measurement to predict induction of labor outcome.

Use of translabial three-dimensional power Doppler ultrasound for cervical assessment before labor induction

OBJECTIVE

To compare translabial three-dimensional (3D) power Doppler ultrasound with Bishop score and transvaginal ultrasound measurements for cervical assessment before induction of labor with dinoprostone or cervical ripening balloon.

MATERIALS AND METHODS

Translabial cervical volume and length, vascularization indices and transvaginal cervical length were measured. Results were compared among women who had vaginal delivery at 24 h or less and more than 24 h after the insertion of the dinoprostone vaginal insert or cervical ripening balloon and among women who had vaginal delivery and cesarean delivery for failure to go into labor or failure to progress.

RESULTS

There was no correlation between the time to delivery after a ripening agent was applied and translabial cervical volume, translabial cervical length, vascularization index (VI), flow index (FI), vascularization flow index (VFI), transvaginal cervical length and Bishop scores. The ultrasonographic measurements were no different among women who had vaginal delivery at 24 h or less and more than 24 h and among women who had vaginal delivery and cesarean delivery for failure to go into labor or failure to progress.

CONCLUSION

In this study, we failed to demonstrate the superiority of translabial 3D ultrasonography over Bishop score and transvaginal ultrasonography for predicting the success of induction of labor.

[The opening of the internal cervical os predicts cervical ripening better than Bishop's score in nulliparous women at 41 weeks gestation]

Introduction

L'objectif était d'évaluer la mesure échographique de l’ouverture de l’orifice interne du col dans la prédiction de l’issue de la maturation cervicale et la comparer au Score de Bishop.

Méthodes

Nous avons mené une étude prospective sur 10 mois, entre Juillet 2012 et avril 2013 colligeant 77 femmes nullipares admises pour déclenchement du travail à un terme de 41 SA avec un Score de Bishop < 6. La mesure de l’ouverture de l’orifice interne du col a été réalisée par échographie transvaginale et le score de Bishop a été déterminé par l'examen clinique. Toutes les patientes ont eu une maturation cervicale par des prostaglandines.

Résultats

La maturation cervicale était réussie chez 63 patients (81%). Le Score de Bishop et l’ouverture de l’orifice interne du col se sont révélés statistiquement associés au succès ou l’échec de la maturation cervicale. Le taux de succès de la maturation était de 100% lorsque l’ouverture de l’orifice interne du col était égale ou supérieure à 5 mm (sensibilité: 54%; spécificité: 86%). Les courbes ROC ont montré que la mesure de l’orifice interne du col était plus prédictive de l’issue de la maturation cervicale que le Score de Bishop (Aire sous la courbe respectivement 0.733 et 0.704).

Conclusion

Comparée au score de Bishop, la mesure échographique de l’ouverture de l’orifice interne du col est plus prédictive du succès de la maturation cervicale chez les femmes nullipares à 41 semaines d’aménorrhée avec un col défavorable.

The value of ultrasound measurement of cervical length and parity in prediction of cesarean section risk in term premature rupture of membranes and unfavorable cervix

AIM

To evaluate the influence of cervical length (CL) and parity as prediction factors for assessment of cesarean section (CS) risk in women with premature rupture of membranes (PROM) at term and unfavorable cervix, undergoing induction of labor (IOL) with dinoprostone intracervical gel.

METHODS

A prospective study involved 50 nulliparous and 51 multiparous women admitted for IOL. Pre-induction CL was measured and delivery outcomes were recorded.

RESULTS

Nulliparous women were younger than the multiparous (26.6±5.2 vs. 30.5±4.9; P<0.001) and had longer pre-induction CL (35.6±5.5 vs. 31.5±4.8; P<0.001) and induction-delivery interval (582 vs. 420 min; P<0.001). There was no difference in the mode of delivery, CS indications, Apgar score, neonatal weight, the rate of neonatal intensive care unit admission and perinatal death in respect of parity. CL was significantly shorter in vaginal vs. cesarean deliveries regardless of parity (31.4 vs. 38.8 mm, P<0.001, respectively). Cut-off values of CL for predicting CS were 37.5 mm in nulliparae and 34.5 mm in multiparae.

CONCLUSIONS

CLs of 37.5 mm in nulliparae and 34.5 mm in multiparae were determined as the cut-off values in predicting CS risk in women with PROM at term and unfavorable cervix.

Pre-induction translabial ultrasound measurements in predicting mode of delivery compared to bishop score: a cross-sectional study

Background

By increased concerns about the accuracy of the traditional methods to predict outcomes after induction of labor, developing new standards has a great clinical importance. Here, we compared the predictive value of translabial ultrasound measurements with Bishop Score to determine the suitability of induction of labor.

Methods

A homogenous population of primigravid women was recruited. Induction of labor was performed with low-dose infusion of oxytocin. Translabial ultrasound and assessment of Bishop Score were performed by two different obstetricians. Receiver–operating characteristics curves were obtained to measure area under curve and subsequently, test sensitivity of each method.

Results

One hundred women entered the investigation. Maternal body mass index was significantly higher among candidates of Cesarean section (P: 0.02). Maternal age and fetus weight, gender and occiput position were not determinants of outcomes of induction of labor. Cervical length and fetal head-pubis symphysis distance measured by translabial ultrasound had a test sensitivity of 90 and 88 %, respectively which were slightly higher than sensitivity of Bishop score (84 %).

Conclusion

This study demonstrates that translabial measurements can be a suitable alternative method to monitor labor progress with an admissible predictive value compared with Bishop Score. It is a non-invasive method which provides valuable objective measurements and can be better accepted by women when considering the painful process which is required in evaluating Bishop Score.

Methods for assessing pre-induction cervical ripening

BACKGROUND

Induction of labour is the artificial initiation of labour in a pregnant woman after the age of fetal viability but without any objective evidence of active phase labour and with intact fetal membranes. The need for induction of labour may arise due to a problem in the mother, her fetus or both, and the procedure may be carried out at or before term. Obstetricians have long known that for this to be successful, it is important that the uterine cervix (the neck of the womb) has favourable characteristics in terms of readiness to go into the labour state.

OBJECTIVES

To compare Bishop score with any other method for assessing pre-induction cervical ripening in women admitted for induction of labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2015) and reference lists of retrieved studies to identify randomised controlled trials (RCTs).

SELECTION CRITERIA

All RCTs comparing Bishop score with any other methods of pre-induction cervical assessment in women admitted for induction of labour. Cluster-RCTs were eligible for inclusion but none were identified. Quasi-RCTs and studies using a cross-over design were not eligible for inclusion. Studies published in abstract form were eligible for inclusion if they provided sufficient information.Comparisons could include the following.1. Bishop score versus transvaginal ultrasound (TVUS).2. Bishop score versus Insulin-like growth factor binding protein-1 (IGFBP-1).3. Bishop score versus vaginal fetal fibronectin (fFN).However, we only identified data for a comparison of Bishop score versus TVUS.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the trials for inclusion, extracted the data and assessed trial quality. Data were checked for accuracy.

MAIN RESULTS

We included two trials that recruited a total of 234 women. The overall risk of bias was low for the two studies. Both studies compared Bishop score withTVUS.The two included studies did not show any clear difference between the Bishop score and TVUS groups for the following main outcomes: vaginal birth (RR 1.07, 95% CI 0.92 to 1.25, moderate quality evidence), caesarean delivery (RR 0.81, 95% CI 0.49 to 1.34, moderate quality evidence), neonatal admission into neonatal intensive care unit (RR 1.67, 95% CI 0.41 to 6.71, moderate quality evidence). Both studies only provided median data in relation to induction-delivery interval and reported no clear difference between the Bishop and TVUS groups. Perinatal mortality was not reported in the included studies.For the review's secondary outcomes, the need for misoprostol for cervical ripening was more frequent in the TVUS group compared to the Bishop score group (RR 0.52, 95% CI 0.41 to 0.66, two studies, 234 women, moderate quality evidence). In contrast, there were no clear differences between the Bishop scope and TVUS groups in terms of meconium staining of the amniotic fluid, fetal heart rate abnormality in labour, and Apgar score less than seven. Only one trial reported median data on the induction-delivery interval and induction to active phase interval, the trialist reported no difference between the Bishop group and the TVUS group for this outcome. Neither of the included studies reported on uterine rupture.

AUTHORS' CONCLUSIONS

Moderate quality evidence from two small RCTs involving 234 women that compared two different methods for assessing pre-induction cervical ripening (Bishop score and TVUS) did not demonstrate superiority of one method over the other in terms of the main outcomes assessed in this review. We did not identify any data relating to perinatal mortality. Whilst use of TVUS was associated with an increased need for misoprostol for cervical ripening, both methods could be complementary.The choice of a particular method of assessing pre-induction cervical ripening may differ depending on the environment and need where one is practicing since some methods (i.e. TVUS) may not be readily available and affordable in resource-poor settings where the sequelae of labour and its management is prevalent.The evidence in this review is based on two studies that enrolled a small number of women and there is insufficient evidence to support the use of TVUS over the standard digital vaginal assessment in pre-induction cervical ripening. Further adequately powered RCTs involving TVUS and the Bishop score and including other methods of pre-induction cervical ripening assessment are warranted. Such studies need to address uterine rupture, perinatal mortality, optimal cut-off value of the cervical length and Bishop score to classify women as having favourable or unfavourable cervices and cost should be included as an outcome.

The role of sonographic cervical length in labor induction at term

The purpose of this study is to review the literature examining the role of ultrasound in the induction of labor. Databases including Ovid, PubMed, Web of Science, Google Scholar, and UpToDate were searched and current guidelines from the SOGC, the ACOG, the RCOG, and the RANZCOG were reviewed. Although studies have not demonstrated the superiority of cervical sonography to the Bishop score, the evidence indicates that sonography could be useful in planning induction of labor, significantly reducing the need for cervical ripening agents. A more comprehensive method integrating both sonography and digital exam may be more appropriate.

Induction of labour

OBJECTIVE

To review the most current literature in order to provide evidence-based recommendations to obstetrical care providers on induction of labour.

OPTIONS

Intervention in a pregnancy with induction of labour.

OUTCOMES

Appropriate timing and method of induction, appropriate mode of delivery, and optimal maternal and perinatal outcomes.

EVIDENCE

Published literature was retrieved through searches of PubMed, CINAHL, and The Cochrane Library in 2010 using appropriate controlled vocabulary (e.g., labour, induced, labour induction, cervical ripening) and key words (e.g., induce, induction, augmentation). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to the end of 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence in this document was rated using criteria described in the Report of the Canadian Task Force on Preventative Health Care (Table 1). SUMMARY STATEMENTS: 1. Prostaglandins E(2) (cervical and vaginal) are effective agents of cervical ripening and induction of labour for an unfavourable cervix. (I) 2. Intravaginal prostaglandins E(2) are preferred to intracervical prostaglandins E(2) because they results in more timely vaginal deliveries. (I).

Transvaginal sonographic assessment of cervical length and wedging for predicting outcome of labor induction at term: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis to assess the predictive capacity of transvaginal sonographic assessment of the cervix for the outcome of induction of labor.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library, and manually searched reference lists of review articles and eligible primary articles. Studies in all languages were eligible if published in full. Two reviewers independently selected studies and extracted data on study characteristics, quality and test accuracy. We then calculated pooled sensitivities and specificities (with 95% CIs) and summary receiver-operating characteristics (sROC) curves. Outcome measures were test accuracy of sonographically measured cervical length and cervical wedging for Cesarean section, not achieving vaginal delivery within 24 h and not achieving active labor.

RESULTS

We included 31 studies reporting on both cervical length and outcome of delivery. The quality of the included studies was mediocre. Sensitivity of cervical length in the prediction of Cesarean delivery ranged from 0.14 to 0.92 and specificity ranged from 0.35 to 1.00. The estimated sROC curve for cervical length indicated a limited predictive capacity in the prediction of Cesarean delivery. Summary estimates of sensitivity/specificity combinations of cervical length at different cut-offs for Cesarean delivery were 0.82/0.34, 0.64/0.74 and 0.13/0.95 for 20, 30 and 40 mm, respectively. For cervical wedging in the prediction of failed induction of labor summary point estimates of sensitivity/specificity were 0.37/0.80.

CONCLUSIONS

Cervical length and cervical wedging as measured sonographically at or near term have moderate capacity to predict the outcome of delivery after induction of labor.

A new objective scoring system for the prediction of successful induction of labour

A prospective study was done in 311 women undergoing induction of labour for the formulation of a new score, which will be more objective than the conventional Bishop's score. Pre-induction cervical assessment was done by the transvaginal sonographic parameters followed by the digital examination. Labour induction was successful in 79.09%. A new score was formulated using the parameters having independent association and weighting of individual components was given according to its regression coefficients. A new score with a maximum value of 13 was proposed. The best cut-off point for the new score in receiver operating characteristics curve was six with a sensitivity of 95.5% and specificity of 84.6%. The new score was found to have a better area under the curve than the conventional score.

Effect of cervical length on second trimester pregnancy termination

AIM

To evaluate the value of sonographic measurement of cervical length as a predictor of abortion or delivery within 24 h by misoprostol in second trimester termination of pregnancy (TOP).

MATERIAL AND METHODS

One hundred and sixty-three women underwent TOP between 14 and 26 weeks of pregnancy due to various indications. The primary outcome was abortion within 24 h. Cervical length was measured before transvaginal administration of misoprostol. The effects of cervical length, total misoprostol dose, parity, and gestational age at diagnosis on successful TOP were evaluated.

RESULTS

  One hundred and sixty-three women were eligible who met the inclusion criteria. TOP occurred in 80.5% of patients within 24 h. Parous women had shorter prolonged induction to expulsion period over 24 h (14.1% vs 28.6%, P = 0.061). Total misoprostol dose and history of abortion were parameters that affected induction to delivery period (P = 0.002 and P = 0.041). Using an optimum cutoff of 36 mm, 58.2% sensitivity and 68.2% specificity were obtained. In addition, positive and negative predictive values were 85.36% and 33.3%, respectively. Pregnant women whose preinduction cervical length was shorter than 36 mm had a shorter induction time and needed a lower total misoprostol dose to achieve TOP than women with a cervical length longer than 36 mm (P = 0.027 and P = 0.011, respectively).

CONCLUSION

Transvaginal measurement of cervical length before administration of prostaglandin analogue was not correlated with successful TOP within 24 h. It cannot be used as a predictor in light of our findings.

Outcome of induction of labour using maternal characteristics, ultrasound assessment and biochemical state of the cervix

OBJECTIVE

To assess pre-induction sonographic, digital examination and biochemical changes in the cervix to predict induction outcome.

METHODS

Transvaginal and abdominal scans were performed in 460 women at 37-41 weeks of gestation to determine cervical length (CL), posterior cervical angle (PCA) and foetal occipital position. The Bishop Score (BS) and the absence/presence of phosphorylated form of insulin-like growth factor-binding protein-1 (phIGFBP-1) in cervical secretions were assessed. Independent parameters significantly associated with a vaginal delivery were identified.

RESULTS

A total of 340 (73.9%) women achieved a vaginal delivery following induction. Multivariate analysis indicated that significant independent predictors of vaginal delivery were CL (adjusted odds ratio [AOR]: 0.59, 95% confidence interval [CI]: 0.45-0.79), PCA (AOR: 1.89, 95% CI: 1.09-3.28) and multiparae (AOR: 10.02, 95% CI: 5.10-19.69). For a specificity of 75%, the sensitivity for prediction of vaginal delivery using the BS, the CL and the multivariate model using the identified significant independent predictors were 37.1, 46.8 and 68%, respectively.

CONCLUSION

The combination of sonographic assessment of the cervix and maternal characteristics was superior to the either BS or CL alone in the prediction of the induction outcome. Inclusion of the absence/presence of phIGFBP-1 did not further improve induction outcome.

Prediction of preterm birth: nonsonographic cervical methods

A short cervix in the second trimester is a powerful predictor of preterm birth risk. Multiple cervical length screens for patients in midpregnancy will likely become the standard of obstetrical care as a result of the development of effective methods (eg, cerclage, progesterone) to prevent early delivery in patients with a short cervix. Because of the high cost and infrastructure requirements, providing multiple cervical length evaluations through transvaginal ultrasound will likely be a significant barrier to universal screening. A cost-effective, low-technology method of cervical length screening is necessary to implement such programs. Available data suggest that digital examination is not sufficiently sensitive and reproducible to reliably screen for short cervix in presymptomatic patients in the mid trimester. New modalities for nonsonographic cervical length assessment (ie, Cervilenz) provide for a cost-effective, sensitive, and reproducible method of screening patients for short cervical length, which deserves further research in comparing its efficacy to sonographic cervical length.

The role of cervical Electrical Impedance Spectroscopy in the prediction of the course and outcome of induced labour

Background

Previous work by us and others had suggested that cervical electrical impedance spectroscopy (EIS) may be predictive of the outcome of induced labour. We sought to determine which probe configuration of the EIS device is predictive of the outcome of induced labour and compare this to digital assessment by the Bishop score.

Methods

In a prospective cohort of 205 women admitted for induction of labour, we used four probes of diameter 3, 6, 9 and 12 mm connected to an impedance meter to measure cervical resistivity (CR) in Ohm.meters at 14 electrical frequencies and compared their values to digital assessment of the cervix by the Bishop score for the prediction of the outcome of induced labour. We tested the association of labour characteristics and outcomes with CR and Bishop score by stepwise multilinear regression analyses, and the accuracy of prediction of categorical clinical outcomes by analysis of the area under the curves (AUC) of derived Receiver Operator Characteristic (ROC) curves.

Results

Of the four CR probe dimensions studied, only the 12 mm probe was predictive of any labour indices. In the frequency range 19 - 156 kHz, CR obtained with this probe was higher in women who delivered by caesarean section (CS) than those who delivered vaginally, and in labours lasting > 24 hrs. Cervical resistivity at 78.1 kHz best predicted vaginal delivery [optimal cut-off <2.25 Ohm.meter, AUC 0.66 (95% CI 0.59-0.72), sensitivity 71.0%, specificity 56.5%, LR+ 1.63, LR- 0.51, P < 0.01] and labour duration >24 hrs [optimal cut-off 2.27 Ω.m, AUC 0.65 (95% CI 0.58, 0.72), sensitivity 71%, specificity 59%, LR+ 1.72, LR- 0.50, P < 0.05]. In contrast digital assessment by the Bishop score neither predicted vaginal delivery nor the duration of labour. However, Bishop score predicted time to onset of labour > 12 hours and induction-delivery interval < 24 hrs [optimal cut-off ≤ 4, AUC 0.8 (95% CI 0.75, 0.86), sensitivity 77%, specificity 76%, LR+ 3.3, LR- 0.3, P < 0.05] whilst CR did not.

Conclusion

Cervical resistivity appears predictive of labour duration and delivery mode following induced labour. However the low predictive values obtained suggest that its current design proffers no immediate clinical utility.

Validation of models that predict Cesarean section after induction of labor

OBJECTIVE

Models for the prediction of Cesarean delivery after induction of labor can be used to improve clinical decision-making. The objective of this study was to validate two existing models, published by Peregrine et al. and Rane et al., for the prediction of Cesarean section after induction of labor.

METHODS

We studied consecutive women in whom labor was induced. In all women, we recorded maternal age, height, body mass index, parity, gestational age and the Bishop score prior to induction. Cervical length was measured by transvaginal ultrasound immediately prior to induction of labor. The primary end-point was delivery by Cesarean section. The calibration of the two prediction models was assessed by comparison of predicted and observed Cesarean delivery rates. The discriminative capacity of the models, i.e. the ability of the models to distinguish subjects who had Cesarean section from those who did not (discrimination), was assessed by receiver-operating characteristics (ROC) analysis.

RESULTS

We included 240 women in the study, of whom 27 (11%) had Cesarean delivery. The capacity of cervical length in the prediction of Cesarean delivery was limited. In our study population, both prediction models overestimated the risk of Cesarean delivery. Calibration was better for the Peregrine et al. model than for the Rane et al. model, and the two models had areas under the ROC curve of 0.76 and 0.67, respectively.

CONCLUSION

Current models that predict the occurrence of Cesarean section after induction of labor have only a moderate predictive capacity when applied within a Dutch practice. We do not recommend the use of these prediction models in clinical practice.

Transvaginal ultrasound measurement of cervical length in the supine and upright positions versus Bishop score in predicting successful induction of labor at term

OBJECTIVES

To examine the predictive value of cervical length as measured by transvaginal sonography (TVS) in supine and upright maternal positions for the mode of delivery and induction-to-delivery interval after induction of labor at term, and to compare these measurements with the Bishop score and its predictive value.

METHODS

TVS for cervical length measurement in the supine and upright positions and digital examination of the cervix were performed in 68 nulliparous and 34 parous women before induction of labor at term. In assessing the predictive value of the Bishop score and TVS parameters for a vaginal delivery after labor induction only nulliparous women were included in the analysis, since all the parous women delivered vaginally. Both nulliparous and parous women were included in the analysis of the induction-to-delivery interval. The method of labor induction, oxytocin or prostaglandin, was determined on the basis of the pre-induction Bishop score.

RESULTS

Logistic regression analysis showed in nulliparous women that only the cervical length measured in the upright position was a significant predictor of the need for Cesarean section (odds ratio 1.14; 95% CI, 1.02-1.27). The areas under the receiver-operating characteristics curve in predicting the need for Cesarean section because of failure to progress were higher for the cervical length, both in supine and upright positions, than for the Bishop score (0.66, 0.68 and 0.46, respectively). Only the Bishop score correlated significantly with the induction-to-delivery interval in both nulliparous and parous women. However, this may have been due to a selection bias, as no significant correlation with Bishop score was found when the oxytocin and prostaglandin induction-to-delivery intervals were analyzed separately.

CONCLUSION

Our results suggest that maternal postural change might improve the accuracy of sonographically-measured cervical length for predicting a vaginal delivery after induction of labor at term. However, our results need to be confirmed in a larger and more homogeneous population.

Ultrasound assessment of fetal head-perineum distance before induction of labor

OBJECTIVES

To evaluate fetal head-perineum distance measured by ultrasound imaging as a predictive factor for induction of labor, and to compare this distance with maternal factors, the Bishop score and ultrasound measurements of cervical length, cervical angle and occiput position.

METHODS

The study included 275 women admitted for induction of labor. The fetal head-perineum distance was measured by transperineal ultrasound imaging as the shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum. Cervical length and angle was measured by transvaginal ultrasound examination, and fetal head position was assessed by transabdominal ultrasound imaging. The Bishop score was assessed without knowledge of ultrasound measurements. Receiver-operating characteristics (ROC) curves were used for evaluation of the probability of a successful vaginal delivery. The time from induction to delivery was tested using Cox regression analysis with ultrasound measurements, parity and body mass index (BMI) as possible predictive factors.

RESULTS

Areas under the ROC curve for prediction of vaginal delivery were 62% (95% CI, 52-71%) for fetal head-perineum distance (P = 0.03), 61% (95% CI, 51-71%) for cervical length (P = 0.03), 63% (95% CI, 52-74%) for cervical angle (P = 0.02), 61% (95% CI, 52-70%) for Bishop score (P = 0.03) and 60% (95% CI, 51-69%) for BMI (P = 0.05). The Cesarean delivery rate was 22% among nulliparous and 5% among parous women (P < 0.01). Parity, fetal head-perineum distance, cervical length and cervical angle were contributing factors predicting vaginal delivery within 24 h in a Cox regression model. Occiput posterior position had no significant predictive value.

CONCLUSIONS

Fetal head-perineum distance measured by transperineal ultrasound examination can predict vaginal delivery after induction of labor, with a predictive value similar to that of ultrasonographically measured cervical length and the Bishop score. However, we judge none of these methods used alone to be good enough in a clinical setting.

Induction of labor with prostaglandins for medical reasons: Determining explanatory variables of the induction to delivery time interval for vaginal deliveries and caesarean section

OBJECTIVE

Aim of the study was to examine the influence of the various medical indications on a successful induction of labor by prostaglandins and to determine the explanatory variables.

STUDY DESIGN

Retrospective analysis of 729 pregnancies, which fulfilled following criteria: only one medical indication for induction, 37 completed weeks of gestation or more, alive singleton pregnancy with cephalic presentation and induction with prostaglandins locally. The chosen endpoint was delivery.

RESULTS

The Kaplan-Meier curves demonstrating the percentage of deliveries in function of the time interval from induction to delivery showed a significant longer time interval for those without pre-labor rupture of membranes (PROM) than for those with PROM as indicated by log rank testing (vaginal deliveries and caesarean sections: hazard ratio=0.67, 95% CI=0.48-0.82, P<0.001; vaginal deliveries only: hazard ratio=0.65; 95% CI=0.45-0.80; P<0.001). In a similar way, those without diabetes had a shorter induction to delivery time interval than those with diabetes when all deliveries, including caesarean sections, were considered (hazard ratio=1.59; 95% CI=1.05-2.06; P=0.02), but there was a "borderline missed" statistical difference when only vaginal deliveries were considered (hazard ratio=1.48; 95% CI=0.96-2.03; P=0.08). Subsequently, univariate analysis in a Cox proportional hazards regression model was used to identify possible explanatory variables of the outcome, followed by multivariate analysis using the Cox proportional hazards regression model again in order to determine the independent contribution of each of these variables to the outcome. Uni- and multivariate analysis showed the cervix score, parity, the number of applied vaginal prostaglandin tablets, the gestational age and PROM to be significant explanatory variables of the induction to delivery time interval. Diabetes, body mass index and body weight were related to the outcome in a univariate analysis, but after adjustment in a multivariate analysis these variables were not significant.

CONCLUSION

PROM was the only medical reason to influence the outcome of an induction with prostaglandins locally, other significant explanatory variables were the cervix score, parity, the number of applied prostaglandin tablets and the gestational age, whereas other factors, such as diabetes, body mass index and body weight had no significant influence.

Predicting a failed induction

BACKGROUND

A failed induction usually refers to failure to progress to the active phase of labour; however, there is no consensus regarding when an induction has failed.

AIMS

To investigate the factors (particularly length of latent phase) that may influence mode of birth for women undergoing Syntocinon induction of labour.

METHODS

A retrospective analysis of 978 nulliparous women undergoing Syntocinon induction of labour following artificial or spontaneous rupture of membranes was performed.

RESULTS

As the length of the latent phase increased, the likelihood of birth by caesarean section increased significantly (P < 0.001). After ten hours of Syntocinon administration, the 8% of women not in the active phase of labour had approximately a 75% chance of being delivered by emergency caesarean section and after 12 h the chance was almost 90%. Multivariate analysis also suggested an association between birth by caesarean section and use of prostaglandin gel (P < 0.001) or mechanical methods of cervical priming (P = 0.004), maternal height < 155 cm (P = 0.020) and cervical dilation prior to commencement of Syntocinon (P = 0.018).

CONCLUSIONS

It would seem reasonable to continue a Syntocinon infusion for at least ten hours in women undergoing induction who have yet to reach the active phase of labour ( 4 cm), and unclear benefit in continuing an induction beyond 12 h. The duration of latent phase is a helpful predictor of subsequent mode of birth.

Pre-induction sonographic assessment of the cervix in the prediction of successful induction of labour in nulliparous women

OBJECTIVE

To compare the efficacy of ultrasonographic cervical assessment with Bishop score before induction of labour in predicting the success of labour induction in nulliparous women.

METHODS

This is a prospective study conducted in 138 women who underwent cervical assessment with transvaginal sonography followed by digital cervical assessment using Bishop score before induction of labour. Ultrasonographic parameters evaluated were cervical length, posterior cervical angle and funnelling were blinded to the managing physicians. Statistical analysis was carried out using Mann-Whitney test, chi2 test, receiver operating characteristics curves and logistic regression analysis.

RESULTS

Induction of labour was successful in 106 (76.8%) of the women. Multiple logistic regression analysis demonstrated cervical length and posterior cervical angle assessed by transvaginal sonography as independent predictors of successful outcome after induction of labour. Neither Bishop score nor its individual parameters were found to be significant in the regression analysis. The area under the receiver operating characteristic curve for cervical length and posterior cervical angle was greater than that of the Bishop score in predicting a successful labour induction. The best cut-off point for the parameters in receiver operating characteristics curve was 3.0 cm for cervical length and 100 degrees for posterior cervical angle. Cervical length of 3.0 cm had a sensitivity of 84.9%, and a specificity of 90.6% and a posterior cervical angle of 100 degrees with 65% and 72%, respectively.

CONCLUSIONS

Transvaginal sonographic assessment of cervical length and posterior cervical angle is better than conventional Bishop score in predicting successful labour induction in nulliparous women.

Sonographic cervical assessment to predict the success of labor induction: a systematic review with metaanalysis

OBJECTIVE

The purpose of this investigation was to review the literature that evaluates sonographic cervical assessment to predict successful induction of labor.

STUDY DESIGN

Published prospective trials that measured sonographic cervical length before labor induction was initiated were evaluated. Trials were excluded if they contained data presented in later articles or did not contain extractable data. The total analysis included 20 trials with 3101 aggregate participants.

RESULTS

Cervical length predicted successful induction (likelihood ratio of positive test, 1.66; 95% confidence interval [CI], 1.20-2.31) and failed induction (likelihood ratio of negative test, 0.51; 95% CI, 0.39-0.67). Cervical length did not predict any specific outcome (eg, mode of delivery). The assessment of cervical wedging proved to be a useful diagnostic test, with a likelihood ratio of a positive test result of 2.64 and a likelihood ratio of a negative test result of 0.64.

CONCLUSION

Sonographic cervical length was not an effective predictor of successful labor induction. Further evaluation of cervical wedging in the prediction of labor induction appears warranted.

Ultrasonographic measurement of cervical length in predicting mode of delivery after oxytocin induction

This study was conducted to explore the value of transvaginal ultrasonographic cervical length measurement, in addition to gestational age, maternal age, parity, Bishop score, and weight of the newborn, in predicting the mode of delivery in pregnancies in which labor is induced with oxytocin at or beyond the 40th gestational week. A total of 73 pregnancies at 40 to 42 weeks of gestation were included. After labor was induced, 29 women delivered vaginally and 44 underwent cesarean section. These groups were compared with respect to possible predictive parameters of delivery outcomes. Student t test, Pearson's correlation analysis, and logistic regression analysis were used for statistical evaluation. Mean preinduction cervical length was 26.8+/-9.9 mm in the vaginal delivery group and 34.2+/-8.1 mm in the cesarean section group (P<.05). Mean maternal age, parity, and Bishop score were significantly higher and mean weight of the newborn was significantly lower in the vaginal delivery group. Cervical length measurements showed a significant negative correlation with Bishop scores (r=-.584; P<.05). Logistic regression analysis revealed that Bishop score (likelihood ratio=.472; 95% confidence interval=.338-.658; P<.05) and weight of the newborn (likelihood ratio=1.002; 95% confidence interval=1.00007-1.003; P<.05) were significant independent predictors of the route of delivery. According to the results of this study, maternal age, parity, Bishop score, cervical length, and weight of the newborn all might affect the mode of delivery after labor induction. Bishop score, although a subjective measure, must be considered an important component of preinduction evaluation.

Transvaginal ultrasound measurement of cervical length and efficacy of misoprostol in first-trimester pregnancy failure

OBJECTIVE

The aim of this study was to assess the role of cervical length measurement in predicting successful treatment, by misoprostol administration, of early (first-trimester) pregnancy failure.

METHOD

A prospective study was conducted of all patients who agreed to medical treatment of pregnancy failure. Cervical length and other sonographic variables were measured using pelvic ultrasound before medical treatment began. Measurements were compared between the group with successful medical treatment and the group in whom treatment failed.

RESULTS

In 125 women included in the study, the success rate of misoprostol treatment was 64.8%. There were no significant differences between the groups with successful and failed treatment for cervical length (29.9 +/- 9.3 vs. 30.4 +/- 6.8 mm, P = 0.75), distance between gestational sac and 'virtual' cervical internal os (23.9 +/- 13 vs. 26.6 +/- 13 mm, P = 0.26), crown-rump length (8.7 +/- 9.7 vs. 6.7 +/- 8.6 mm, P = 0.25), or gestational sac diameter (31.3 +/- 14 vs. 30.1 +/- 15 mm, P = 0.73).

CONCLUSION

Cervical length does not predict the success of misoprostol treatment of first-trimester pregnancy failure.

Cervical ripening with a Foley catheter: the role of pre- and postripening ultrasound examination of the cervix

OBJECTIVE

The objective of the study was to assess sonographic changes in cervical length and posterior cervical angle in women undergoing cervical ripening with an extraamniotic Foley catheter and to determine whether pre- and postripening ultrasound parameters could help predict successful cervical ripening and the outcome of labor induction.

STUDY DESIGN

Cervical length and posterior cervical angle were measured by transvaginal sonography in 155 women with a Bishop score of 4 or less before placement of a transcervical Foley catheter for cervical ripening. At the time of Foley removal, women who did not enter active labor underwent a second ultrasound assessment of the cervix. Outcome measures were successful ripening, vaginal delivery, vaginal delivery within 24 hours, and vaginal delivery achieved with the Foley only. Multiple logistic regression models were generated to identify pre- and postripening clinical and ultrasound parameters independently associated with successful induction.

RESULTS

Forty patients (25.8%) went into active labor after spontaneous expulsion or removal of the Foley, without any additional intervention. A successful cervical ripening was obtained with the transcervical catheter in 46 women (29.6%). One hundred six women (68.4%) had vaginal delivery. No correlation was found among maternal body mass index, maternal age, clinical cervical dilatation, sonographic posterior cervical angle, and any of the outcomes of interest. Multiple logistic regression showed that preripening sonographic cervical length was an independent predictor of successful ripening (odds ratio [OR] 10.2, 95% confidence interval [CI] 3.6 to 28.5), vaginal delivery (OR 2.6, 95% CI 1.2 to 5.5), vaginal delivery achieved with only Foley (OR 17.2, 95% CI 3.9 to 76.2), and vaginal delivery within 24 hours (OR 3.3, 95% CI 1.5 to 7.3). In the subgroup of women who did not enter labor with the transcervical Foley, at the time of catheter removal, a significant change was found in sonographic cervical length (33.1 mm [12.2 to 54.1] vs 24.0 mm [7.6 to 42], P < .0001] and sonographic posterior cervical angle (110 degrees C [70-160] vs 137 degrees C [88-170], P < .0001), compared with preripening findings. Transvaginal ultrasound cervical length was the only postripening characteristic that independently predicted vaginal delivery (OR 3.5, 95% CI 1.3 to 9.1).

CONCLUSION

Transvaginal sonography seems a useful diagnostic tool to assess objectively the efficacy of the Foley catheter as ripening method and helps predict the likelihood of a successful induction of labor in individual women who require preinduction cervical ripening.

Bishop score and ultrasound assessment of the cervix for prediction of time to onset of labor and time to delivery in prolonged pregnancy

OBJECTIVES

To determine the ability of Bishop score and sonographic cervical length to predict time to spontaneous onset of labor and time to delivery in prolonged pregnancy.

METHODS

Ninety-seven women underwent transvaginal ultrasound examination and palpation of the cervix at 291-296 days' gestation according to ultrasound fetometry at 12-20 weeks' gestation. Sonographic cervical length and Bishop score were recorded. Multivariate logistic regression analysis was used to determine which variables were independent predictors of the onset of labor/delivery < or = 24 h, < or = 48 h, and < or = 96 h. Receiver-operating characteristics (ROC) curves were drawn to assess diagnostic performance.

RESULTS

In nulliparous women (n = 45), both Bishop score and sonographic cervical length predicted the onset of labor/delivery < or = 24 h and < or = 48 h (area under ROC curve for the onset of labor < or = 24 h 0.79 vs. 0.80, P = 0.94; for delivery < or = 24 h 0.81 vs. 0.85, P = 0.64; for the onset of labor < or = 48 h 0.73 vs. 0.74, P = 0.90; for delivery < or = 48 h 0.77 vs. 0.71, P = 0.50). Only Bishop score discriminated between nulliparous women who went into labor/delivered < or = 96 h or > 96 h. A logistic regression model including Bishop score and cervical length was superior to Bishop score alone in predicting delivery < or = 24 h (area under ROC curve 0.93 vs. 0.81, P = 0.03) and superior to Bishop score alone and cervical length alone in predicting the onset of labor < or = 24 h (area under ROC curve 0.90 vs. 0.79, P = 0.06; and 0.90 vs. 0.80, P = 0.06). In parous women (n = 52), Bishop score and sonographic cervical length predicted the onset of labor/delivery < or = 24 h (area under ROC curve for the onset of labor 0.75 vs. 0.69, P = 0.49; for delivery 0.74 vs. 0.70, P = 0.62), but only Bishop score discriminated between women who went into labor/delivered < or = 48 h and > 48 h. Three parous women had not gone into labor and six had not given birth at 96 h. In parous women logistic regression models including both Bishop score and cervical length did not substantially improve prediction of the time to onset of labor/delivery.

CONCLUSIONS

In prolonged pregnancy Bishop score and sonographic cervical length have a similar ability to predict the time to the onset of labor and delivery. In nulliparous women the use of logistic regression models including Bishop score and cervical length is likely to offer better prediction of the onset of labor/delivery < or = 24 h than the use of the Bishop score alone.

Preinduction Cervical Assessment

The rate of labor induction is increasing in the United States. Methods for quantifying cervical factors have been developed to identify patients who may benefit from cervical ripening before induction. The first cervical scoring systems used digital examination. More recently, cervical ultrasound and testing for the presence of fetal fibronectin have been suggested to evaluate cervical readiness for labor induction, but neither of these methods provides a significant improvement over digital examination. The Bishop score, the most widely used digital examination scoring system, still is the most cost effective and accurate method of evaluating the cervix before labor induction.

Factors Predicting Labor Induction Success: A Critical Analysis

Because of the risk of failed induction of labor, a variety of maternal and fetal factors as well as screening tests have been suggested to predict labor induction success. Certain characteristics of the woman (including parity, age, weight, height and body mass index), and of the fetus (including birth weight and gestational age) are associated with the success of labor induction; with parous, young women who are taller and lower weight having a higher rate of induction success. Fetuses with a lower birth weight or increased gestational age are also associated with increased induction success. The condition of the cervix at the start of induction is an important predictor, with the modified Bishop score being a widely used scoring system. The most important element of the Bishop score is dilatation. Other predictors, including transvaginal ultrasound (TVUS) and biochemical markers [including fetal fibronectin (fFN)] have been suggested. Meta-analyses of studies identified from MEDLINE, PubMed, and EMBASE and published from 1990 to October 2005 were performed evaluating the use of TVUS and fFN in predicting labor induction success in women at term with singleton gestations. Both TVUS and Bishop score predicted successful induction [likelihood ratio (LR)=1.82, 95% confidence interval (CI)=1.51-2.20 and LR=2.10, 95%CI=1.67-2.64, respectively]. As well, fFN and Bishop score predicted successful induction (LR=1.49, 95%CI=1.20-1.85, and LR=2.62, 95%CI=1.88-3.64, respectively). Although TVUS and fFN predicted successful labor induction, neither has been shown to be superior to Bishop score. Further research is needed to evaluate these potential predictors and insulin-like growth factor binding protein-1 (IGFBP-1), another potential biochemical marker.

[Evaluation of controlled-release dinoprostone Propess for labor induction]

OBJECTIVE

To evaluate the efficacy of cervix ripening with vaginal controlled-release Propess.

PATIENTS AND METHODS

A retrospective study of all women who underwent cervical ripening with Propess during the study period from 1(st) January 2002 to 31(st) December 2004 was carried out. A total of 130 patients who experienced Propess was compared with the next following patient who delivered spontaneously matched on gestational age. Modes of delivery, failure of labor, maternal morbidity were recorded.

RESULTS

Indications for induction of labor were: post-term pregnancies in 18.5%, pre-eclampsia in 20.8%, oligohydroamnios in 18.5%, post-term pregnancy and oligohydramnios in 10.8%, intra-uterine fetal growth in 6.9%, premature rupture of membranes in 6.9%, diminution of fetal mobility in 6.1% and miscellaneous in 11.5%. Failure of cervical ripening was 21.2%. Patients in the Propess group had a 3.5 fold higher risk of Cesarean section [95% CI: 1.5-8.3; P < 0.04]. There was no case of maternal or fetal death. There was no difference in incidence of maternal complications, and post-partum haemorrhage.

DISCUSSION AND CONCLUSION

Use of vaginal pessary Propess does not induce adverse maternal or fetal morbidity. However, it was associated with a higher incidence of Cesarean delivery.

Clinical and Ultrasound Parameters to Predict the Risk of Cesarean Delivery After Induction of Labor

OBJECTIVE

To evaluate whether factors in the maternal history and/or ultrasound parameters are useful in predicting the risk of cesarean delivery after induction of labor.

METHODS

Maternal age, height, body mass index, parity, gestational age, Bishop score, ultrasonic amniotic fluid volume, fetal head position, estimated fetal weight, and transvaginal cervical length were studied prospectively in 267 women at 36 or more weeks of gestation immediately before induction of labor. Logistic regression analysis was used to determine which factors best predicted the risk of cesarean delivery. Receiver operating characteristic curves and a resampling technique were used to evaluate the model's performance.

RESULTS

Eighty (30%) of these 267 women had cesarean delivery. Logistic regression was performed and a final model chosen, which included parity (odds ratio [OR] 20.56, 95% confidence interval [CI] 7.97-53.05, P < .001), body mass index (OR 6.17, 95% CI 2.10-18.13, P < .001), height (OR 0.94, 95% CI 0.89-0.98, P = .005), and ultrasonic transvaginal cervical length (OR 1.07, 95% CI 1.04-1.11, P < .001) as the best predictors of cesarean delivery. A risk score was calculated containing these 4 parameters, which predicted reasonably accurately the risk of cesarean delivery.

CONCLUSION

Parity, body mass index, height, and ultrasonic transvaginal cervical length are the most accurate parameters in predicting the risk of cesarean delivery after induction of labor. A predictive model using these would allow more accurate counseling and better informed consent in the decision-making process regarding induction of labor

LEVEL OF EVIDENCE

II-2.