Sonographic cervical length as a predictor of type of delivery after induced 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.

A machine learning model to predict spontaneous vaginal delivery failure for term nulliparous women: An observational study

OBJECTIVE

This study aims to construct and evaluate a model to predict spontaneous vaginal delivery (SVD) failure in term nulliparous women based on machine learning algorithms.

METHODS

In this retrospective observational study, data on nulliparous women without contraindications for vaginal delivery with a singleton pregnancy ≥37 weeks and before the onset of labor from September 2020 to September 2021 were divided into a training set and a temporal validation set. Transperineal ultrasound was performed to collect angle of progression, head-perineum distance, subpubic arch angle, and their levator hiatal dimensions. The cervical length was measured via transvaginal ultrasound. The delivery methods were later recorded. Through LASSO regression analysis, indicators that can affect SVD failure were selected. Seven common machine learning algorithms were selected for model training, and the optimal algorithm was selected based on the area under the curve (AUC) to evaluate the effectiveness of the validation model.

RESULTS

Four indicators related to SVD failure were identified through LASSO regression screening: angle of progression, cervical length, subpubic arch angle, and estimated fetal weight. The Gaussian NB algorithm was found to yield the highest AUC (0.82, 95% confidence interval [CI] 0.65-0.98) during model training, and hence it was chosen for verification with the temporal validation set, in which an AUC of 0.79 (95% CI 0.64-0.95) was obtained with accuracy, sensitivity, and specificity rates of 80.9%, 72.7%, and 75.0%, respectively.

CONCLUSION

The Gaussian NB model showed good predictive effect, proving its potential as a clinical reference for predicting SVD failure of term nulliparous women before actual delivery.

A model to predict delivery time following induction of labor at term with a dinoprostone vaginal insert: a retrospective study

BACKGROUND

Dinoprostone vaginal insert is the most common pharmacological method for induction of labor (IOL); however, studies on assessing the time to vaginal delivery (DT) following dinoprostone administration are limited.

AIMS

We sought to identify the primary factors influencing DT in women from central China, at or beyond term, who underwent IOL with dinoprostone vaginal inserts.

METHODS

In this retrospective observational study, we analyzed the data of 1562 women at 37 weeks 0 days to 41 weeks 6 days of gestation who underwent dinoprostone-induced labor between January 1st, 2019, and December 31st, 2021. The outcomes of interest were vaginal or cesarean delivery and factors influencing DT, including maternal complications and neonatal characteristics.

RESULTS

Among the enrolled women, 71% (1109/1562) delivered vaginally, with median DT of 740.50 min (interquartile range 443.25 to 1264.50 min). Of the remaining 29% (453/1562), who delivered by cesarean section, 11.9% (54/453) were multiparous. Multiple linear regression analysis showed that multiparity, advanced maternal age, fetal macrosomia, premature rupture of membranes (PROM), and daytime insertion of dinoprostone were the factors that significantly influenced DT. Time to vaginal delivery increased with advanced maternal age and fetal macrosomia and decreased with multiparity, PROM, and daytime insertion of dinoprostone. A mathematical model was developed to integrate these factors for predicting DT: Y = 804.478 - 125.284 × multiparity + 765.637 × advanced maternal age + 411.511 × fetal macrosomia-593.358 × daytime insertion of dinoprostone - 125.284 × PROM.

CONCLUSIONS

Our findings may help obstetricians estimate the DT before placing a dinoprostone insert, which may improve patient management in busy maternity wards and minimize potential risks.

A randomized clinical trial of Premaquick biomarkers versus transvaginal cervical length for pre-induction cervical assessment at term among pregnant women

Objectives

To compare Premaquick biomarkers (combined insulin-like growth-factor binding protein 1 and interleukin-6) and cervical length measurement via transvaginal ultrasound for pre-induction cervical evaluation at term among pregnant women.

Methods

A randomized clinical trial of consenting pregnant women at the Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria. The women were randomized equally into Premaquick group (n = 36) and transvaginal ultrasound group (n = 36). The cervix was adjudged 'ripe' if the Premaquick test was positive or if the trans-vaginal measured cervical length was less than 28 mm. The primary outcome measures were the proportions of women who needed prostaglandin analogue for cervical ripening and the proportion that achieved vaginal delivery after induction of labour. The trial was registered in Pan African clinical trial registry (PACTR) registry with approval number PACTR202001579275333.

Results

The baseline characteristics were similar between the two groups (p > 0.05). There was no statistically significant difference between the two groups in terms of proportion of women that required prostaglandins for pre-induction cervical ripening (41.7 versus 47.2%, p = 0.427), vaginal delivery (77.8 versus 80.6%, p = 0.783), mean induction to delivery interval (22.9 ± 2.81 h versus 24.04 ± 3.20 h, p = 0.211), caesarean delivery (22.2 versus 19.4%, p = 0.783), proportion of neonate with birth asphyxia (8.30 versus 8.30%, p = 1.00) and proportion of neonate admitted into special care baby unit (16.7 versus 13.9%, p = 0.872). Subgroup analysis of participants with 'ripe' cervix at initial pre-induction assessment showed that the mean induction to active phase of labour interval and mean induction to delivery interval were significantly shorter in Premaquick than transvaginal ultrasound group.

Conclusion

Pre-induction cervical assessment at term with either Premaquick biomarkers or transvaginal ultrasound for cervical length is effective, objective and safe with similar and comparable outcome. However, when compared with women with positive transvaginal ultrasound at initial assessment, women with positive Premaquick test at initial assessment showed a significantly shorter duration of onset of active phase of labour and delivery of baby following induction of labour.

Labour induction in twin pregnancies

Medically-indicated deliveries are common in twin pregnancies given the increased risk of various obstetric complications in twin compared to singleton pregnancies, mainly hypertensive disorders of pregnancy and foetal growth restriction. Due to the unique characteristics of twin pregnancies, the success rates and safety of labour induction may be different than in singleton pregnancies. However, while there are abundant data regarding induction of labour in singleton pregnancies, the efficacy and safety of labour induction in twin pregnancies have been far less studied. In the current manuscript we summarize available data on various aspects of labour induction in twin pregnancies including incidence, success rate, prognostic factors, safety and methods for labour induction in twins. This information may assist healthcare providers in counselling patients with twin pregnancies when labour induction is indicated.

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.

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.

Prognostic models in obstetrics: available, but far from applicable

Health care provision is increasingly focused on the prediction of patients' individual risk for developing a particular health outcome in planning further tests and treatments. There has been a steady increase in the development and publication of prognostic models for various maternal and fetal outcomes in obstetrics. We undertook a systematic review to give an overview of the current status of available prognostic models in obstetrics in the context of their potential advantages and the process of developing and validating models. Important aspects to consider when assessing a prognostic model are discussed and recommendations on how to proceed on this within the obstetric domain are given. We searched MEDLINE (up to July 2012) for articles developing prognostic models in obstetrics. We identified 177 papers that reported the development of 263 prognostic models for 40 different outcomes. The most frequently predicted outcomes were preeclampsia (n = 69), preterm delivery (n = 63), mode of delivery (n = 22), gestational hypertension (n = 11), and small-for-gestational-age infants (n = 10). The performance of newer models was generally not better than that of older models predicting the same outcome. The most important measures of predictive accuracy (ie, a model's discrimination and calibration) were often (82.9%, 218/263) not both assessed. Very few developed models were validated in data other than the development data (8.7%, 23/263). Only two-thirds of the papers (62.4%, 164/263) presented the model such that validation in other populations was possible, and the clinical applicability was discussed in only 11.0% (29/263). The impact of developed models on clinical practice was unknown. We identified a large number of prognostic models in obstetrics, but there is relatively little evidence about their performance, impact, and usefulness in clinical practice so that at this point, clinical implementation cannot be recommended. New efforts should be directed toward evaluating the performance and impact of the existing models.

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.