Transvaginal sonographic measurement of cervical length vs. Bishop score in labor induction at term: tolerability and prediction of Cesarean delivery

The significance of ultrasound parameters and clinical factors in predicting successful labor induction among nulliparous women

OBJECTIVES

To compare the values of ultrasound and clinical parameters for predicting outcomes of induction of labor (IOL) among healthy nulliparous women with a singleton, term cephalic pregnancy.

METHODS

The cervical length, cervical strain elastography, posterior cervical angle, head-perineum distance, Bishop score, and maternal parameters were assessed before IOL with a combined method-Foley catheter and Misoprostol perorally. The main outcome was vaginal delivery.

RESULTS

Variation in cervical tissue elasticity, represented by elasticity index (E), was significantly different between outcome groups-vaginal delivery and cesarean section (CS) in internal os, in the anterior lip near the cervical canal and the midpoint of the anterior and posterior lip (p < 0.05). The E was higher-softer in the vaginal delivery group. The overall elasticity was significantly higher in the middle part of the cervix in the vaginal delivery group. However, other ultrasound metrics did not differ significantly across the outcome groups. Overall, women who delivered vaginally were taller and had a lower pre-pregnancy BMI (p = 0.02 for both variables). Univariate and multivariate analyses showed maternal height was the significant independent predictor of CS (AOR 0.91, 95% CI 0.84-0.98). The prognostic value for vaginal delivery, based on cervical length, maternal height, Bishop score, and parameters of cervical strain elastography, was poor (AUC < 0.7).

CONCLUSION

The study underscores the importance of cervical tissue elasticity in predicting vaginal delivery outcomes, while also highlighting that maternal height is a significant independent predictor of cesarean delivery. However, evaluated metrics in the study have limited prognostic value for predicting vaginal delivery. This suggests a need for further research to identify more reliable predictors of delivery outcomes.

Strain ratio elastography of the uterine cervix and prediction of successful labor induction

BACKGROUND

Before labor induction, the uterine cervix is often evaluated by the Bishop score, or a modified Bishop score, to predict the duration and success of induction. However, more objective methods are wanted. Strain ratio elastography is a technique that evaluates the elastic modulus of a tissue. Using strain ratio elastography in combination with a reference material enables quantitative elastography of the uterine cervix.

OBJECTIVE

To evaluate the associations between the apparent elastic modulus of the cervical tissue assessed by strain ratio elastography and the cervical dilation time after labor induction.

METHODS

Twenty-two nulliparous pregnant women admitted for labor induction were included. A Bishop score, a cervical length measured by ultrasound and an elastic modulus evaluated by strain ratio elastography were obtained from all participants. Primary outcomes were cervical dilation time from labor induction to active labor and from active labor to full cervical dilation.

RESULTS

The strain ratio was not associated with the time from labor induction to active labor R2: 0,024 (P = 0.492), but there was a small association between strain ratio and time from active labor to full cervical dilatation R2: 0.180, however not significant (P = 0.063). The cervical length was associated with time from labor induction to active phase R2: 0.134 (P = 0.003), but not with time from active labor to full dilatation R2: 0.015 (P = 0.610).

CONCLUSIONS

The results indicate a possible importance of the elastic modulus for predicting time from active labor to full cervical dilatation, whereas the cervical length seems to be of greater importance for time from labor induction to active labor.

Transvaginal ultrasonography-measured cervical length versus the modified Bishop score for preinduction cervical assessment at term: A randomised controlled trial

Introduction

The inducibility of the cervix for labour induction is usually determined by cervical status evaluation. The Bishop score is historically used to forecast the success of induction of labour, although it is subjective, and not reproducible. However, transvaginal ultrasound measurements of cervical length are rarely used for preinduction cervical assessment. The study compared cervical length measured via transvaginal ultrasound and the modified Bishop score for preinduction cervical assessment at term.

Methods

The study involved 72 pregnant, nulliparous women for induction of labour at term. They were randomised into the transvaginal ultrasound group and the modified Bishop score group. The cervix was said to be 'ripe' when the transvaginal ultrasound cervical length (CL) was < 28 mm or the modified Bishop score was ⩾ 6. The cervix was considered 'unripe' when the Bishop score was < 6 or the transvaginal ultrasound was ⩾ 28 mm. Participants with ripe cervices had induction of labour with an oxytocin infusion, while those with unripe cervices had preinduction cervical ripening with misoprostol. The primary outcome measures were the mode of delivery and the total amount of prostaglandins administered for preinduction cervical ripening.

Results

There was no significant difference between the two groups with regard to the mode of delivery (p = 0.795), the total amount of prostaglandins administered for preinduction cervical ripening (105.0 ± 51.04 µg vs 111.90 ± 52.2 µg; p = 0.0671), the proportion of women who were administered prostaglandins due to an unfavourable cervix (41.7% vs 55.6%; p = 0.812), induction-to-the-active phase of the labour interval (11.00 ± 4.2 hours vs 11.82 ± 4.12 hours; p = 0.407) or the induction-delivery interval (20.15 ± 5.7 hours vs 22.66 ± 4.33 hours; p = 0.06) in both groups, respectively. Compared with those in the Bishop score group (Bishop score ⩾ 6), the induction-to-active phase of labour intervals (6.47 ± 0.77 hours vs 7.33 ± 1.21 hours, p = 0.024) and the induction-to-delivery intervals (14.97 ± 1.0 hours vs 18.39 ± 0.85 hours; p = 0.0001) in the transvaginal ultrasound group (cervical length < 28 mm) were significantly shorter, respectively.

Conclusion

Preinduction cervical assessment using transvaginal ultrasound (cervical length < 28 mm) or the modified Bishop score is a successful predictor of the outcome of labour induction A larger multicentre studies are needed to identify optimal cervical length cutoffs and to determine if this could decrease unnecessary prostaglandin use or decrease caesarean section rate.

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.

The Impact of Cervical Effacement at Time of Amniotomy in Patients Undergoing Induction of Labor

OBJECTIVE

There is evidence to suggest that early amniotomy during induction of labor is advantageous. However, following cervical ripening balloon removal, the cervix remains less effaced and the utility of amniotomy in this setting is less clear. We investigated whether cervical effacement at the time of amniotomy impacts outcomes among nulliparas undergoing induction of labor.

STUDY DESIGN

This was a secondary analysis of a prospective cohort of singleton, term, nulliparous patients at a tertiary care center undergoing induction of labor and amniotomy. The primary outcome was completion of the first stage of labor. Secondary outcomes were vaginal delivery and postpartum hemorrhage. Outcomes were compared between patients with cervical effacement ≤50% (low effacement) and >50% (high effacement) at time of amniotomy. Multivariable logistic regression was used calculate risk ratios (RR) to adjust for confounders including cervical dilation. Stratified analysis was performed in patients with cervical ripening balloon use. A post hoc sensitivity analysis was performed to further control for cervical dilation.

RESULTS

Of 1,256 patients, 365 (29%) underwent amniotomy at low effacement. Amniotomy at low effacement was associated with reduced likelihood of completing the first stage (aRR: 0.87 [95% confidence interval, CI: 0.78-0.95]) and vaginal delivery (aRR: 0.87 [95% CI: 0.77-0.96]). Although amniotomy at low effacement was associated with lower likelihood of completing the first stage in all-comers, those who had amniotomy performed at low effacement following cervical ripening balloon expulsion were at the highest risk (aRR: 0.84 [95% CI: 0.69-0.98], p for interaction = 0.04) In the post hoc sensitivity analysis, including patients who underwent amniotomy at 3- or 4-cm dilation, low cervical effacement remained associated with a lower likelihood of completing the first stage of labor.

CONCLUSION

Low cervical effacement at time of amniotomy, particularly following cervical ripening balloon expulsion, is associated with a lower likelihood of successful induction.

KEY POINTS

· Low cervical effacement at amniotomy was associated with lower rates of complete dilation.. · Effacement at amniotomy is especially important for patients who had a cervical ripening balloon.. · Providers should consider cervical effacement when timing amniotomy for nulliparous term patients..

Nomogram based on the final antepartum ultrasound features before delivery for predicting failed spontaneous vaginal delivery in nulliparous women

Background

Accurate identification of nulliparous women with failed spontaneous vaginal delivery (SVD) is crucial to minimize the hazards associated with obstetrical intervention (OI). While abnormal labor progression can be identified with intrapartum ultrasonography, labor-related complications may be unavoidable due to the limited time window left to the obstetrician. Antepartum ultrasound enables sufficient obstetric planning. However, there is typically a longer gap between ultrasound assessment and delivery that often lowers the prediction accuracy compared to intrapartum ultrasonography.

Objective

In this study, antepartum ultrasound assessment was included to each fetal ultrasound examination after 36 weeks of gestation until the onset of labor. We aim to establish a nomogram to predict the likelihood of failed SVD in nulliparous women using the last antepartum ultrasound findings before labor beginning.

Methods

Of the 2,143 nulliparous women recruited, 1,373 were included in a training cohort and 770 in a validation cohort, based on their delivery date. Maternal and perinatal characteristics, as well as perinatal ultrasound parameters were collected. In the training cohort, the screened correlates of SVD failure were used to develop a nomogram for determining whether a nulliparous woman would experience SVD failure. This model was validated in both training and validation cohorts.

Results

SVD failure affected 217 nulliparous women (10.13%). In the training cohort, SVD failure was independently associated with BMI [odds ratio (OR) = 1.636], FHC (OR = 1.194), CL (OR = 1.398), and PCA (OR = 0.824) (all P < 0.05). They constituted a nomogram to estimate the individual risk of SVD failure. The model obtained clinical net benefits in both the training and validation cohorts and was validated to present strong discrimination and calibration.

Conclusion

The developed nomogram based on the last antepartum ultrasound findings may be helpful in avoiding OI and its related complications by assessing the likelihood of a failed SVD in nulliparous women.

Pre-induction cervical assessment using transvaginal ultrasound versus Bishops cervical scoring as predictors of successful induction of labour in term pregnancies: A hospital-based comparative clinical trial

Objective

To evaluate the association between transvaginal ultrasound scan of cervix and Bishop’s score in predicting successful induction of labour, cut-off points and patients’ tolerability and acceptance for both procedures.

Design

A comparative clinical trial.

Setting

A tertiary hospital in Selangor, Malaysia.

Participants

294 women planned for elective induction of labour for various indications were included. All women had transvaginal ultrasound to assess the cervical length and digital vaginal examination to assess the Bishop cervical scoring by separate investigators before induction of labour.

Primary outcome measure

To evaluate the association of the cervical length by transvaginal ultrasound scan and Bishop score in predicting successful induction of labour.

Secondary outcome measure

Variables associated with successful induction of labour and patients’ tolerability and acceptance for transvaginal ultrasound scan of cervix.

Results

There was no statistically significant difference among the vaginal and Caesarean delivery groups in terms of mean maternal age, height, weight, body mass index, ethnicity and gestational age at induction. Vaginal delivery occurred in 207 women (70.4%) and 87 women (29.6%) delivered via Caesarean section. There was a high degree of correlation between the cervical length and Bishop score (r-value 0.745; p <0.001). Sonographic assessment of cervical length demonstrated a comparable accuracy in comparison to Bishop score. Analysis using ROC curves noted an optimal cut-off value of ≤27mm for cervical length and Bishop score of ≥ 4, with a sensitivity of 69.1% vs 67%, specificity 60.9% vs 55%, and area under the curves (AUCs) of 0.672 and 0.643 respectively (p <0.001). Multivariate logistic regression analysis demonstrated that parity (OR 2.70), cervical length (OR 0.925), Bishop score (OR 1.272) and presence of funnelling (OR 3.292) were highly significant as independent predictors of success labour induction. Women also expressed significantly less discomfort with transvaginal ultrasound compared with digital vaginal examination.

Conclusion

Sonographic assessment of cervical measurement predicts the success of induction of labour with similar diagnostic accuracy with conventional Bishop score.

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.

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.

Transvaginal two-dimensional ultrasound measurement of cervical volume to predict the outcome of the induction of labour: a prospective observational study

Background

Assessing the likelihood of success of induction of labour using ultrasonically measured cervical volume is an important research question.

Method

A prospective observational study was carried out at North Colombo Teaching Hospital, Ragama, Sri Lanka. Pre-induction digital cervical assessment, transvaginal cervical length, and cervical volume measurements were performed. Inductions with singleton pregnancies at term were included. Basic demographic and clinical details, independent variables (Bishop score, cervical length and cervical volume), and dependent variables (frequency of delivery within 24 h and induction to delivery interval) were recorded. Vaginal delivery within 24 h was the primary outcome.

Results

We studied 100 pregnant women who had induction of labour. Median (IQR) Bishop score was 5 (3–6), mean (SD) cervical length was 3.6 (0.7) cm, and mean (SD) cervical volume was 27.5 (10.4) cm³. Cervical length was the best predictor for predicting the likelihood of vaginal delivery within 24 h [aOR – 12.12 (3.44, 42.71); < 0.001], and cervical volume also appeared to be a significant potential predictor [aOR-1.10 (1.01, 1.17); 0.01]. Cervical length was found to have the highest AUC (0.83) followed by the cervical volume (0.74). The best cut-off value for cervical volume in predicting the likelihood of vaginal delivery within 24 h was less than 28.5 cm³ with a sensitivity of 72% and specificity of 74%.

Conclusions

Transvaginal sonographic measurement of cervical volume appears to be a potential novel predictor for the likelihood of vaginal delivery within 24 h of induction of labour. Cervical length is still more superior to cervical volume in predicting the likelihood of vaginal delivery. Bishop score was not a significant predictor in this context.

The usefulness of ultrasound before induction of labor

The indications for induction of labor have been consistently on the rise. These indications are mainly medical (maternal or fetal) or social or related to convenience or maternal preferences. With the increase in the prevalence of these indications, the incidence rates of induction of labor are expected to rise continuously. This poses a substantial workload and financial burden on maternity healthcare systems. Failure rates of induction of labor are relatively high, especially when considering the maternal, fetal, and neonatal risks associated with emergency cesarean deliveries in cases of failure. Therefore, it is essential for obstetricians to carefully select women who are eligible for induction of labor, particularly those with no clinical contraindication and who have a reasonable chance of ending up with a successful noncomplicated vaginal delivery. Ultrasound has an established role in the various areas of obstetrical care. It is available, accessible, easy to perform, and acceptable to the patient. In addition, the learning curve for skillful obstetrical ultrasound scanning is rather easy to fulfill. Ultrasound has always had an important role in the assessment of maternal and fetal well-being. Indeed, it has been extensively explored as a reliable, reproducible, and objective tool in the management of labor. In this review, we aimed to provide a comprehensive update on the different applications and uses of ultrasound before induction of labor for the prediction of its success and the potential improvement of its health-related maternal and fetal outcomes.

The degree of cervical length shortening as a predictor of successful or failed labor induction

OBJECTIVE

To evaluate whether the degree of cervical length change was associated with successful cervical dilatation during labor induction.

MATERIALS AND METHODS

We conducted a secondary analysis of a prospective observational study of term singleton pregnant women who underwent labor inductions. Cases of Cesarean section due to fetal distress or maternal request during the first stage of labor were excluded. The enrolled women were categorized into two groups according to achievement of full cervical dilatation. The cervical length near induction and cervical length shortening over the last four weeks of pregnancy were compared between the two groups. A receiver operating characteristics (ROC) analysis was performed to evaluate the screening performance for failed cervical dilatation during labor induction.

RESULTS

A total of 165 women were enrolled for the final analysis; of these, 145 (87.9%) women reached the second stage of labor and 20 (12.1%) women failed to achieve full cervical dilatation. Women who failed to achieve full cervical dilatation had a significantly longer cervical length near induction and less cervical length change over previous four weeks compared with women who achieved full cervical dilatation (P = 0.018 and 0.005, respectively). Multivariate analysis showed that cervical length >29 mm (odds ratios [OR], 4.15; 95% confidence interval [CI], 1.290-13.374, P = 0.017) and cervical length shortening ≦ 6 mm (OR, 5.87; 95% CI, 1.552-22.271, P = 0.009) were significantly associated with failed cervical dilatation after adjusting for birthweight and previous history of vaginal delivery. Cervical length shortening alone provided a better prediction of failed cervical dilatation than the combination of cervical length and shortening (sensitivity, 76.9%; specificity, 63.8%).

CONCLUSION

The probability of failed cervical dilatation during labor induction was significantly increased in cases when the cervical length was greater than 29 mm near induction or when the cervical length shortening was less than 6 mm over the last four weeks.

Role of Cervical Phosphorylated Insulin-Like Growth Factor-Binding Protein 1 (phIGFBP1) for Prediction of Successful Induction Among Primigravida with Prolonged Pregnancy

Purpose of the Study

To estimate and to compare the levels of cervical phIGFBP-1 among primigravida with prolonged pregnancy, with and without successful induction of labor (IOL).

Methods

A diagnostic study (cross-sectional study design) was conducted in our institution from November 2016 to April 2018 on 84 primigravida at ≥ 41 weeks with uncomplicated singleton pregnancy. The results were analyzed using SPSS software and receiver operating characteristics curves to determine the best cutoff using Youden Index. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive (+ LR) and negative likelihood ratio (- LR) were calculated. P value < 0.05 was considered significant. Logistic regression analysis was used to determine the predictive ability of the three markers for successful IOL.

Results

The cutoff level of phIGFBP-1, Bishop score (BS) and transvaginal cervical length (TVL) were 7.8 µg/l, 3 and 3.5 cm, respectively. The sensitivity, specificity, PPV, NPV, + LR and - LR of phIGFBP-1 (> 7.8 µg/l) were 0.87, 0.87, 0.89, 0.85, 6.76 and 0.15, respectively. Using logistic regression analysis, phIGFBP-1 was found to be the best predictor of successful IOL (OR 44.200; 95% CI 12.378-157.831, p < 0.001).

Conclusion

phIGFBP-1 is a strong independent predictor successful IOL as compared to TVL and BS in primigravida with prolonged pregnancy.

Spectroscopic photoacoustic imaging of cervical tissue composition in excised human samples

Objective

Cervical remodeling is an important component in determining the pathway of parturition; therefore, assessing changes in cervical tissue composition may provide information about the cervix’s status beyond the measurement of cervical length. Photoacoustic imaging is a non-invasive ultrasound-based technology that captures acoustic signals emitted by tissue components in response to laser pulses. This optical information allows for the determination of the collagen-to-water ratio (CWR). The purpose of this study was to compare the CWR evaluated by using spectroscopic photoacoustic (sPA) imaging in cervical samples obtained from pregnant and non-pregnant women.

Methods

This cross-sectional study comprised cervical biopsies obtained at the time of hysterectomy (n = 8) and at the scheduled cesarean delivery in pregnant women at term who were not in labor (n = 8). The cervical CWR was analyzed using a fiber-optic light-delivery system integrated to an ultrasound probe. The photoacoustic signals were acquired within the range of wavelengths that cover the peak absorption of collagen and water. Differences in the CWR between cervical samples from pregnant and non-pregnant women were analyzed. Hematoxylin and eosin and Sirius Red stains were used to compare the collagen content of cervical samples in these two groups.

Results

Eight cervix samples were obtained after hysterectomy, four from women ≤41 years of age and four from women ≥43 years of age; all cervical samples (n = 8) from pregnant women were obtained after 37 weeks of gestation at the time of cesarean section. The average CWR in cervical tissue samples from pregnant women was 18.7% (SD 7.5%), while in samples from non-pregnant women, it was 55.0% (SD 20.3%). There was a significantly higher CWR in the non-pregnant group compared to the pregnant group with a p-value <0.001. A subgroup analysis that compared the CWR in cervical samples from pregnant women and non-pregnant women ≤41 years of age (mean 46.3%, SD 23.1%) also showed a significantly higher CWR (p <0.01). Lower collagen content in the pregnancy group was confirmed by histological analysis, which revealed the loss of tissue composition, increased water content, and collagen degradation.

Conclusion

The proposed bimodal ultrasound and sPA imaging system can provide information on the biochemical composition of cervical tissue in pregnant and non-pregnant women. Photoacoustic imaging showed a higher collagen content in cervical samples from non-pregnant women as compared to those from pregnant women, which matched with the histological analysis. This novel imaging method envisions a new potential for a sensitive diagnostic tool in the evaluation of cervical tissue composition.

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.

The Effect of Ultrasound-Measured Preinduction Cervical Length on Delivery Outcome in a Low-Resource Setting

Background

Induction of labour is not without risk, and it calls for a method that will be sensitive enough to predict successful labour induction.

Aim

This study aims to evaluate the role of transvaginal ultrasonographic cervical length measurement at term in the prediction of successful induction of labour (IOL).

Materials and Methods

This prospective study was carried out in the Department of Obstetrics and Gynaecology of Federal Teaching Hospital Abakaliki between 1st of July and 30^th of November 2015. Preinduction Bishop score and cervical length were assessed before induction of labour. Intracervical, cervical, extraamniotic Foley catheter was used to improve the Bishop score. The data were analyzed using the IBM SPSS Statistics 20.

Results

The mean maternal age of the study group was 30.68 ± 6.38 years with a range of 19–43 years. The mean gestational age and parity were 39.57 ± 1.49 and 1.85 ± 0.63, respectively. All the women studied had successful induction of labour with mean induction delivery time of 8.1 ± 3.0 hours and mean duration of labour of 7.4 ± 2.9 hours. Preinduction cervical length is a good predictor of a short duration of labour (P = 0.001). Parturient with a preinduction cervical length of less than 3 cm was likely to have labour lasting less than 6 hours (RR = 4.20 (95% CI 1.85–9.529).

Conclusion

Transvaginal sonographic measurement of cervical length provides a useful prediction of the likelihood of duration of labour following the induction of labour. It is recommended that IOL should be considered and success anticipated in a parturient with a cervical length less than 3 cm.

Predicting labor induction success by cervical funneling in uncomplicated pregnancies

Aim

Predictive accuracy of cervical funneling for successful vaginal delivery prior to labor induction was compared to that of conventional methods such as Bishop score and cervical length.

Methods

Prospective observational study was conducted on nulliparous women at 38 gestational weeks or more with intact membranes who delivered vaginally following labor induction. Transvaginal ultrasound was performed prior to labor induction to evaluate the cervix, to determine the cervical length and to check for the presence of funneling. Following pelvic examinations, the Bishop score was calculated. Predictive accuracy of the three different methods, namely cervical funneling, cervical length and Bishop, were compared.

Results

A total of 235 nulliparous women with intact membranes were recruited. Of these, 194 women (82.6%) had successful vaginal deliveries following induction. Cervical funneling was observed in 105 women (44.7%). The rate of successful vaginal delivery was significantly higher in women with cervical funneling than in those without funneling (90.5% vs 76.2%, P < 0.004). Multivariable analysis showed that cervical funneling, similar to traditional measures such as the Bishop score and cervical length, was an independent predictor of successful vaginal delivery following labor induction (odds ratio = 2.95; 95% confidence interval: 1.38–6.47; P = 0.007).

Conclusions

Similar to the conventional methods of cervical evaluation, such as the Bishop score and cervical length, cervical funneling may serve as a useful and valid predictor of successful vaginal deliveries prior to labor induction.

The predictive value of cervical shear wave elastography in the outcome of labor induction

Introduction

Bishop score, the traditional method to assess cervical condition, is not a promising predictive tool of the outcome of labor induction. As an objective assessment tool, many cervical ultrasound measurements have been proposed to represent the individual components of the Bishop score, but none of them can measure the cervical stiffness. Cervical shear wave elastography is a novel tool to assess the cervical stiffness quantitatively.

Material and methods

A total of 475 women who required labor induction were studied prospectively. Prior to routine digital assessment of the Bishop score, transvaginal sonographic measurement of cervical length, posterior cervical angle, angle of progression and shear wave elastography was performed. Shear wave elastography measurement was made at the inner, middle and outer regions of the cervix to assess homogeneity. Association of labor induction outcomes including the overall cesarean section and subgroups of cesarean section for failure to enter active phase, with cervical sonographic parameters and the Bishop score, were assessed using multivariate regression analyses. The predictive accuracy of the outcomes using models based on ultrasound measurement and the Bishop score was compared using the area under the receiver‐operating characteristics curves.

Results

Among 475 women, 82 (17.3%) required cesarean section. Shear wave elasticity was significantly higher in the inner cervical region than in other regions, indicating a greater stiffness (P < 0.001). Both inner cervical shear wave elasticity and cervical length were independent predictors of overall cesarean section (respective adjusted odds ratio [95% CI] 1.338 [1.001‐1.598] and 1.717 [1.077‐1.663]) and cesarean section for failure to enter active phase (respective adjusted odds ratio [95% CI] 1.689 [1.234‐2.311] and 2.556 [1.462‐4.467]), after adjusting for other covariates. Outcome prediction models using inner cervical shear wave elasticity and cervical length, had increased area under curve compared with models using the Bishop score (0.888 vs 0.819, P = 0.009).

Conclusions

The cervix is not a homogenous structure, with the inner cervix having the highest stiffness, which is an independent predictor of overall cesarean section, and specifically for those indicated because of failure to enter active phase. Models based on shear wave elastography and cervical length had higher predictive accuracy than models based on the Bishop score.

Development and Validation of a Risk Prediction Model for Cesarean Delivery After Labor Induction

Objective: The goal of the study was to develop and validate a prediction model for cesarean delivery after labor induction that included factors known before the start of induction, unlike prior studies that focused on characteristics at the time of induction. Materials and Methods: Using 17,370 term labor inductions without documented medical indications occurring at 14 U.S. hospitals, 2007-2012, we created and evaluated a model predicting cesarean delivery. We assessed model calibration and discrimination, and we used bootstrapping for internal validation. We externally validated the model by using 2122 labor inductions from a hospital not included in the development cohort. Results: The model contained eight variables-gestational age, maternal race, parity, maternal age, obesity, fibroids, excessive fetal growth, and history of herpes-and was well calibrated with good risk stratification at the extremes of predicted probability. The model had an area under the curve (AUC) for the receiver operating characteristic curve of 0.82 (95% confidence interval 0.81-0.83), and it performed well on internal validation. The AUC in the external validation cohort was 0.82. Conclusion: This prediction model can help providers estimate a woman's risk of cesarean delivery when planning a labor induction.

Accuracy of the Manipal Cervical Scoring System for predicting successful induction of labour

The Manipal Cervical Scoring System is an accurate and objective sonographic score that predicts the outcome of induced labour. The aim of the current study was to compare the performance of the Manipal Cervical Scoring System against the Bishop Score. A prospective study was conducted on 105 women underwent labour induction in Ain Shams University Hospital, Cairo, Egypt. Both scores were assessed pre-induction. Successful induction occurred in 78.09% of the cases. The area under the ROC curve (AUC) was of 0.940 (95% CI = 0.876 to 0.977; p value <.0001) for the Manipal Score and 0.863 (95% CI = 0.783-0.923; p value <.0001) for the Bishop Score. The Manipal Score >5 had a sensitivity of 91.5% and a specificity of 91.3%. While the Bishop score >4 had a sensitivity of 98.8% and specificity of 69.6% to predict the outcome of induced labour. The Manipal Cervical Scoring system is a better objective tool to predict the outcome of labour induction compared to the Bishop Score. However, other female and fetal characteristics, including body mass index (BMI) at gestation, gestational weight gain, occiput position and parity should be taken into consideration when performing labour induction. Impact statement What is already known on this subject? The ultimate fate of 20% of women having an induction of labour (IOL) is a Caesarean delivery. Thus, predicting the possible response to IOL before starting induction could guide clinicians to determine the efficacy of starting and/or continuing the induction process and in counselling women regarding the possible response to IOL. The main predictor for IOL outcome is based on the pre-induction cervical status which has been traditionally assessed by the Bishop Score. However, the Bishop Score remains subjective, thereby, associated with high rates of bias and several studies have demonstrated its poor predictive value for the outcome of induction. What do the results of this study add? Proposed use of ultrasound parameters that are equivalent to Bishop Score will be objective, reliable and reproducible method. It allows for patient re-evaluation by other obstetricians without the need for re-examination (thus decreasing exposing the patient to pain and anxiety). What are the implications of these findings for clinical practice and/or further research? According to WHO and FIGO, oral misoprostol (25 μg, 2-hourly) is recommended for induction of labour. This helps to decrease the discomfort of repeated vaginal examination and increases the women satisfaction with labour process, especially in women at higher risk of infection. Thus evaluating cervical status using an ultrasound cervical scoring system can similarly increase women's satisfaction with labour process. Our goal in the upcoming trial is to perform RCT comparing ultrasound versus Bishop in women undergoing IOL using oral misopristol regarding measures of satisfaction during labour in the parturient women.

Vaginal assessment and expedited amniotomy in oral misoprostol labor induction in nulliparas: a randomized trial

BACKGROUND

Labor is induced in 20-30% of maternities, with an increasing trend of use. Labor induction with oral misoprostol is associated with reduced risk of cesarean deliveries and has a safety and effectiveness profile comparable to those of mechanical methods such as Foley catheter use. Labor induction in nulliparous women continues to be challenging, with the process often quite protracted. The eventual cesarean delivery rate is high, particularly when the cervix is unfavorable and ripening is required. Vaginal examination can cause discomfort and emotional distress particularly to nulliparous women, and plausibly can affect patient satisfaction with the induction and birth process.

OBJECTIVE

The aim of this study was to evaluate regular (4-hourly prior to each oral misoprostol dose with amniotomy when feasible) compared with restricted (only if indicated) vaginal assessments during labor induction with oral misoprostol in term nulliparous women MATERIALS AND METHODS: We performed a randomized trial between November 2016 and September 2017 in a university hospital in Malaysia. Our oral misoprostol labor induction regimen comprised 50 μg of misoprostol administered 4 hourly for up to 3 doses in the first 24 hours. Participants assigned to regular assessment had vaginal examinations before each 4-hourly misoprostol dose with a view to amniotomy as soon as it was feasible. Participants in the restricted arm had vaginal examinations only if indicated. Primary outcomes were patient satisfaction with the birth process (using an 11-point visual numerical rating scale), induction to vaginal delivery interval, and vaginal delivery rate at 24 hours.

RESULTS

Data from 204 participants (101 regular, 103 restricted) were analyzed. The patient satisfaction score with the birth process was as follows (median [interquartile range]): 7 [6-9] vs 8 [6-10], P = .15. The interval of induction to vaginal delivery (mean ± standard deviation) was 24.3 ± 12.8 vs 31.1 ± 15.0 hours (P = .013). The vaginal delivery rate at 24 hours was 27.7% vs 20.4%; (relative risk [RR], 1.4; 95% confidence interval [CI], 0.8-2.3; P = .14) for the regular vs restricted arms, respectively. The cesarean delivery rate was 50% vs 43% (RR, 1.1; 95% CI, 0.9-1.5; P = .36). When assessed after delivery, participants' fidelity to their assigned vaginal examination schedule in a future labor induction was 45% vs 88% (RR, 0.5; 95% CI, 0.4-0.7; P < .001), and they would recommend their assigned schedule to a friend (47% vs 87%; RR, 0.6; 95% CI, 0.5-0.7; P < .001) in the regular compared with the restricted arms, respectively.

CONCLUSION

Despite a shorter induction to vaginal delivery interval with regular vaginal examination and a similar vaginal delivery rate at 24 hours and birth process satisfaction score, women expressed a higher preference for the restricted examination schedule and were more likely to recommend such a schedule to a friend.

Labor Induction Techniques: Which Is the Best?

Induction of labor is a common procedure undertaken whenever the benefits of prompt delivery outweigh the risks of expectant management. Cervical assessment is essential to determine the optimal approach. Indication for induction, clinical presentation and history, safety, cost, and patient preference may factor into the selection of methods. For the unfavorable cervix, several pharmacologic and mechanical methods are available, each with associated advantages and disadvantages. In women with a favorable cervix, combined use of amniotomy and intravenous oxytocin is generally the most effective approach. The goal of labor induction is to ensure the best possible outcome for mother and newborn.

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 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.

Prediction of Preterm Delivery by Late Cervical Length Measurement after 24 Weeks

Objective: To examine the value of the cervical length (CL) measurement at 24-30 gestational weeks in the prediction of spontaneous preterm delivery (SPD) between 30 and 34 weeks (SPD34) and between 34 and 37 weeks (SPD37). Methods: We performed a prospective cross-sectional study. CL was measured once by transvaginal ultrasound examination between 24 and 30 weeks. Results: The study sample consisted of 1,180 low-risk singleton pregnancies. 10 women (0.85%) had a SPD34 and 60 (5.08%) had a SPD37. CL was shorter (p < 0.001) in the women who had a SPD34 (median 11 mm) compared to the women who delivered after 34 weeks (median 31 mm). CL was shorter (p < 0.001) in the women who had a SPD37 (median 22 mm) compared to the women who delivered after 37 weeks (median 31 mm). CL predicted SPD34 (OR = 0.837, R2 = 0.2768, AUC = 0.9406, p < 0.001) and SPD37 (OR = 0.907, R2 = 0.1085, AUC = 0.7584, p < 0.001). The model achieved a sensitivity of 70.0 and 38.3% for 10% false-positive rate for SPD34 and SPD37, respectively. Conclusions: CL after 24 weeks is significantly shorter in women destined to have a SPD. In low-risk singleton pregnancies CL performs very well in predicting SPD34 and adequately in predicting SPD37.

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.

Sonographically accessed funneling of the uterine cervix as a predictor of successful labor induction

OBJECTIVE

The Bishop score and length of the uterine cervix are good predictors of successful labor induction. However, little is known about the association between the funneling of the uterine cervix and successful labor induction. The study aimed to evaluate cervical funneling as a predictor of successful labor induction.

METHODS

This study was designed as a prospective observational study. Subjects who delivered a baby by labor induction were enrolled in the study from July 2011 to August 2013. Cervical funneling and length were examined with transvaginal ultrasonography. The Bishop score was rated by digital pelvic examination.

RESULTS

A total of 163 primigravida women were recruited for the study. Of these, 137 participants (84.0%) delivered vaginally by labor induction. Cervical funneling was observed in 93 women (57.1%). Successful labor induction was significantly higher in patients with cervical funneling than those without it (91.4% vs. 74.3%, P<0.01), and was significantly associated with cervical funneling, as well as the Bishop score and cervical length. In a multivariate analysis, cervical funneling was an independent predictor for successful vaginal delivery by labor induction ( odd ratio, 2.70; 95% confidence interval, 1.02 to 7.10; P=0.04). However, the Bishop score and cervical length had no association with successful vaginal delivery.

CONCLUSION

This study showed that cervical funneling could be a predictive marker for vaginal delivery during labor induction.

Manipal Cervical Scoring System by Transvaginal Ultrasound in Predicting Successful Labour Induction

INTRODUCTION

Induction of labour (IOL) nowadays is a common procedure in obstetric practice. The success of IOL largely depends upon "favourability" or "readiness" cervix which is traditionally assessed by manual examination and Scored as Bishop Score. However, this method is limited by subjectivity and reproducibility and though done in all the patients prior to IOL, several studies have demonstrated poor correlation between Bishop Score and outcome of labour.

OBJECTIVE

To evaluate the role of preinduction transvaginal ultrasonographic (TVS) cervical assessment in predicting labour outcome and to compare its performance against Bishop Score in patients undergoing induction of labour (IOL).

SETTING

A tertiary medical college hospital in Southern India.

DESIGN

Prospective observational and investigational study.

MATERIALS AND METHODS

Transvaginal ultrasound was performed in 131 patients who underwent labour induction at term with intact membranes and live fetus. Bishop Score was assessed by pervaginal examination and was compared with preinduction TVS cervical Score (parameters being cervical length, funneling, position of cervix and distance of presenting part from external os). Labour was induced within one hour of cervical assessment. The labour induction was considered successful if patient could get into active labour i.e., onset of regular uterine contractions (at interval of 2-3 minutes) and cervical dilatation of 4 cm or greater within 24 hours of induction.

RESULTS

Labour induction was successful in 86.9% of patients. At cut off Scores of ≥ 4, TVS cervical Score performed better than Bishop Score (Sensitivity 77% vs. 65%, Specificity 93% vs. 86%). ROC analysis indicated that Area Under Curve (AUC) was more for TVS Score (0.90, 95% CI 0.84 - 0.95), compared to Bishop Score. It was found that an increase in cervical length and distance from the os by 1 mm from their means were associated with an increase in odds for failure of induction and there by caesarean delivery by 6.5% and 11% respectively.

CONCLUSION

In women experiencing labour induction, transvaginal ultrasound score comprising of five different parameters indicated success of induction better than Bishop Score. Further, two of its components (longer cervical length and increased distance of presenting part from external os) demonstrated significant and independent prediction of the likelihood of failure of induction and risk of operative delivery.

Cervical length in late second and third trimesters: a mixture model for predicting delivery

OBJECTIVES

To examine the distribution of cervical length (CL) in the late second and third trimesters of pregnancy and construct survival models for spontaneous delivery.

METHODS

This cross-sectional study included 647 women with a singleton pregnancy who had routine CL measurements taken by transvaginal ultrasonography between 24 and 40 weeks' gestation. Only one measurement per patient was included in the analysis. Exploratory data analysis revealed that the distribution of CL measurements was a mixture of two Gaussian distributions, and subsequently a mixture model was applied to describe the distribution of CL. Changes in CL in relation to gestational age were examined by regression analysis and measurements were converted to Z-scores. Survival analysis was applied to the subgroups identified, to describe the probability of delivery throughout gestation.

RESULTS

CL was best described by a mixture model of two subgroups with Gaussian distribution, one including women with a long cervix (73.85% of the study population, mean CL of 28.2 ± 4.45 mm) and the other including women with a short cervix (26.15% of the study population, mean CL of 12.3 ± 5.14 mm). CL was dependent on gestational age (GA), therefore conversion to Z-scores was employed in the analysis. Women with a short cervix had a higher probability for spontaneous delivery (hazard ratio (HR), 1.807; P < 0.001) than did women with a long cervix, after adjustment for GA at the time of measurement (GA HR, 1.115; P < 0.001). In both subgroups, the probability of spontaneous delivery was predicted by the GA and CL Z-scores. Survival models for the prediction of spontaneous delivery were constructed separately for the short-cervix subgroup (GA HR, 1.085; P < 0.001 and CL Z-score HR, 0.819; P = 0.003) and the long-cervix subgroup (GA HR, 1.130; P < 0.001 and CL Z-score HR, 0.864; P = 0.005).

CONCLUSIONS

CL follows a mixture of two Gaussian distributions, one for a short and one for a long cervix. Late second-trimester/third-trimester CL measurement may be of value in estimating the probability for spontaneous delivery at any given gestational age.

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.

Can measurement of cervical length, fetal head position and posterior cervical angle be an alternative method to Bishop score in the prediction of successful labor induction?

AIM

The purpose of this study was to evaluate sonographic cervical length, posterior cervical angle and fetal head position in predicting successful induction of labor at term can be an alternative method to Bishop score.

METHODS

This prospective observational study recruited 223 women with singleton gestations scheduled for induction of labor at 37-42 weeks. Parity, body mass index, Bishop score, fetal head position, cervical angle measurement and cervical length was investigated to predict successful labor induction. Multiple regression analysis was performed to determine the parameters in the prediction of successful vaginal delivery within 24 hours.

RESULTS

Forty-five patients were excluded because of cesarean section performed for other reasons than arrest of dilation or fetal head descent (43 fetal distress, 2 cord prolapsus). Remaining 178 patients were divided into two groups according to duration of delivery time. 139 patients delivered within 24 hours were classified as group I, 39 patients delivered after 24 hours were classified as group II. Percentage of multiparity was statistically significantly higher in group I than in group II [59 (42.4%), 9 (23.0%) respectively, p = 0.009]. Cervical length was statistically significantly shorter in group I than in group II [23.1 ± 7.42 mm, 31.3 ± 6.83 mm respectively, p < 0.001]. Bishop score was statistically significantly higher in group I than in group II [3 (1-4), 1 (1-4) respectively, p < 0.001]. Posterior cervical angle was statistically significantly higher in group I than in group II [100.1 ± 17.2, 92.7 ± 21.4 respectively, p = 0.007]. According to the fetal head position, there was no statistically significant difference in labor duration between the groups (p = 0.787). In the multivariate regression analysis of variables, multiparity, cervical length and Bishop score were statistically significantly predictive in successful labor induction.

CONCLUSION

Multiparity status, cervical length, posterior cervical angle and Bishop score can predict successful labor induction, but fetal head position is not predictive in successful labor induction.

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.

Comparison between sonographic cervical length and Bishop score in preinduction cervical assessment: a randomized trial

OBJECTIVE

To compare sonographically measured cervical length with the Bishop score in determining the requirement for prostaglandin administration for preinduction cervical ripening in nulliparae at term.

METHODS

One hundred and fifty-four women with singleton pregnancies at term who were scheduled for induction of labor were randomly assigned to receive prostaglandin for preinduction cervical ripening based on the Bishop score or sonographic cervical length. A cervix unfavorable for treatment with prostaglandin for preinduction cervical ripening was defined as having either a Bishop score of ≤ 4 or a cervical length of ≥ 28 mm. The primary outcome measures were induction success (defined as an ability to achieve the active phase of labor) and the percentage of patients treated with prostaglandin for preinduction cervical ripening.

RESULTS

The two groups were similar with respect to maternal demographics, gestational age, cervical length, and Bishop score. The rates of induction success and Cesarean delivery, the interval to active phase of labor, and the interval to delivery were also similar in the two groups. However, in the transvaginal ultrasound group (n = 77), prostaglandin was administered to only 36% of the nulliparae compared with 75% of those in the Bishop score group (n = 77) (P < 0.0001).

CONCLUSION

In comparison with the Bishop score, the use of sonographic cervical length for assessing the cervix prior to induction of labor can reduce the need for prostaglandin administration by approximately 50% without adversely affecting the outcome of induction in nulliparae at term if the cut-off values used are a Bishop score of ≤ 4 and a cervical length of ≥ 28 mm.

Additional effects of the cervical length measurement in women with preterm contractions: a systematic review

Purpose

Transvaginal cervical length measurement in women with symptoms of preterm labor has been used to decide if treatment is necessary. Cervical length measurement may also have additional effects on patients, such as providing reassurance, although the evidence to support this is unclear. We explored and summarized to what extent additional effects of cervical length measurement in women with threatened preterm labor have been reported in the clinical literature and what the magnitude of these effects was.

Methods

We performed a systematic review of the literature to identify articles reporting on cervical length measurements in women with symptoms of preterm labor. We assessed whether these articles reported patient outcomes other than preterm delivery.

Results

The electronic and hand search resulted in 764 articles, of which 172 met initial criteria for further eligibility assessment. We found 12 articles that reported additional effects of cervical length measurement in symptomatic women, such as the reassurance or the sensory consequences related to the transvaginal procedure. None of the articles quantified such additional effects.

Conclusions

There appears to be a gap between the presumed effects of cervical length measurement on patient outcomes, such as patients’ reassurance, and the actual assessment of these effects during test evaluations. We suggest that future evaluations of prognostic preterm labor tests include a comprehensive assessment of patient outcomes.

Effect of membrane sweeping on cervical length by transvaginal ultrasonography and impact of cervical shortening on cesarean delivery

OBJECTIVES

The purpose of this study was to evaluate cervical length changes after membrane sweeping and the effect of cervical shortening on pregnancy outcomes.

METHODS

Low-risk women at 40 weeks' gestation undergoing membrane sweeping to expedite labor were recruited. Participants were scheduled for labor induction at 41 weeks' gestation. Transvaginal ultrasonography was performed immediately before and after membrane sweeping to measure the cervical length. Three presweep and postsweep cervical lengths were measured. The shortest lengths before and after the sweep were taken as the representative lengths. The effect of membrane sweeping on cervical length was analyzed. Multivariable logistic regression analysis was performed to evaluate the effect of cervical shortening on labor induction and the mode of delivery.

RESULTS

For the 160 participants, the mean presweep cervical length ± SD was 21.0 ± 10.0 mm; the postsweep length was 23.8 ± 10.9 mm, an average increase of 2.8 ± 0.6 mm (P < .001). Cervical shortening after membrane sweeping was noted in 53 of 160 cases (33%). Cervical shortening was associated with a reduction in all-cause cesarean delivery but not labor induction on bivariate analysis. After adjustment for maternal age, parity, presweep Bishop score, postsweep cervical length, oxytocin augmentation, epidural analgesia, and meconium-stained fluid, cervical shortening after membrane sweeping was independently predictive of a reduction in cesarean deliveries (adjusted odds ratio, 0.24; 95% confidence interval, 0.06-0.90; P = .034).

CONCLUSIONS

Membrane sweeping was associated with lengthening of the cervix. A shortened cervix after sweeping was independently predictive of vaginal delivery.