Comparing Transvaginal Ultrasound Measurements of Cervical Length to Bishop Score in Predicting Cesarean Section Following Induction of Labor: A Prospective Observational Study

INTRODUCTION

 Bishop score (BS) has been used to see the favorability of the cervix for induction of labor (IOL), but it has limitations in today's diverse patient population. We aimed to assess the predictive value of transvaginal ultrasound (TVUS) measurements of cervical length (CL) compared to BS in determining the likelihood of cesarean section (CS) following IOL.

METHODOLOGY

A prospective observational study was conducted on 120 women requiring IOL in a tertiary care hospital in central India. The inclusion criteria of the study were antenatal women more than 18 years of age, in need of IOL, having a singleton pregnancy with a gestational age of > 37 weeks as determined from the date of the last menstrual period and confirmed by sonographic measurements in the first trimester, presenting with a cephalic presentation, and having intact fetal membranes. Women with prior uterine scars and those unwilling to IOL were excluded from the study. TVUS was done just before induction. Statistical analyses were done to compare the predictive abilities of CL and BS for CS.

RESULTS

The mean age and gestation period were 25.96 years and 39 weeks 3 days, respectively. The majority of the study population comprised multigravida (69, 57.5%), followed by primigravida (47, 39.2%), and grand multigravida (≥ G5) (4, 3.3%). Post-maturity (34, 28.3%), preeclampsia (21, 17.5%), and intrahepatic cholestasis of pregnancy (17, 14.2%) were common indications for induction. The overall CS rate was 35.8% (43/120). Women with CS had lower BS (3.60 vs. 4.70, P = 0.010) and higher CL (31.5 mm vs. 23.4 mm, P < 0.001). CL exhibited an area under the curve (AUC) of 0.857, outperforming BS (AUC = 0.643) in predicting CS. Using a CL cutoff of 26.5 mm yielded sensitivity (79.1%), specificity (81.8%), and overall accuracy (80.8%).

CONCLUSIONS

TVUS measurement of CL (>26.5 mm) demonstrated superior predictive ability for CS following labor induction compared to BS (≤5). This study highlights the potential of CL measurement as an objective and reliable tool for optimizing decision-making in labor induction.

Comparison of the Efficacy and Safety of Sublingual Versus Oral Misoprostol for the Induction of Labor: A Randomized Open-Label Study

Introduction Misoprostol (prostaglandin E1 analog) is being used for the induction of labor by vaginal, oral, and sublingual routes. Oral misoprostol is the preferred route for induction of labor, but the use of sublingual misoprostol appears promising due to a faster onset of action. This study was done to compare the efficacy and safety of oral and sublingual misoprostol for induction of labor in term pregnancy. Materials and methods One hundred and sixty patients were randomly allocated to one of the two groups to receive 50 micrograms of oral and sublingual misoprostol four hourly for a maximum of six doses. Primigravida at 37-42 weeks of gestation with singleton pregnancy, cephalic presentation, Bishop score (<5), and reassuring fetal heart rate were included in the study. Misoprostol dose was withheld if the active phase of labor was reached or if the cervix was favorable for amniotomy (Bishop score greater than or equal to eight). The change in the Bishop score with misoprostol was studied along with adverse effects and neonatal outcomes. Results The mean number of 50 mcg misoprostol doses required was significantly less in the sublingual group (2.94±0.97 versus 2.13±0.92; p<0.0001). The rate of change of the mean Bishop score was faster in the sublingual group. After four hours of the first dose, the mean Bishop score changed to 3.52±2.14 versus 4.68±2.34 (p=0.001), and, similarly, after eight hours, it was 10.48±2.59 versus 11.39±2.06, and this difference was statistically significant (p=0.015). The mean induction delivery interval was significantly lower in the sublingual group. The need for labor augmentation, mode of delivery, and adverse effects were similar in both groups. The incidence of meconium-stained liquor and NICU admission was also similar in both groups. Conclusion Sublingmisoprostolstol has a short induction delivery interval and comparable side effects when compared to omisoprostolstol. Sublingmisoprostolstol is recommended for induction of labor at term.

Comparison of Intracervical Foley's Catheter With Vaginal Misoprostol Versus Intravaginal Misoprostol Alone for Cervical Ripening and Induction of Labor

Introduction Induction of labor implies stimulation of contractions before the spontaneous onset of labor, with or without membranes. Augmentation refers to the enhancement of spontaneous contractions that are considered inadequate because of failed cervical and fetal descent. This study compared the effectiveness of intracervical Foley catheter insertion and vaginal misoprostol versus only vaginal misoprostol in the induction of labor and other outcomes relted to it. Methods The present study was a randomized controlled trial that included 148 women divided into two groups: (i) Group A, which received intracervical Foley catheter insertion and vaginal misoprostol (25 µg), and (ii) Group B, which received intravaginal administration of tablet misoprostol (25 µg) alone. We compared the median time from the time of induction to vaginal delivery, incidence of cesarean delivery, chorioamnionitis, puerperal infection, uterine tachysystole, neonatal information at delivery, and discharge status (i.e., birth weight, neonatal intensive care unit (NICU) admission, and neonatal death) between groups. Results We found that the rates of puerperal infection (n=36; 48.6%) and meconium-stained amniotic fluid (n=45; 60.8%) were higher in Group B than in Group A (n=20; 27.0% and n=25; 33.8%, respectively), which were statistically significant differences (p=0.0066 and p=0.0009, respectively). In addition, NICU admission was higher in Group B (n=47; 63.5%) than in Group A (n=30; 40.5%), which was a statistically significant difference (p=0.0051). Conclusion An intracervical Foley catheter with 25 µg of misoprostol was more effective for induction of labor than 25 µg of intravaginal misoprostol alone every six hours for a maximum of four doses in terms of induction to delivery interval, meconium-stained amniotic fluid, mode of delivery, intrapartum complications, and puerperal infection.

Repeatability and Reproducibility of Potential Ultrasonographic Bishop Score Parameters

Determination of the Bishop score (BS) is a traditional method of assessing the cervix in obstetrics and gynecology. This examination is characterized by subjectivity of assessment and low repeatability. In scientific studies intended to evaluate the results of the procedure based on the initial assessment, it is necessary to find an objective scale based on ultrasonography. We selected five ultrasound parameters, measured with a transvaginal transducer, that are equivalent to the individual BS axes (dilatation assessed in three-dimensional ultrasound (DL), angle of progression (AoP), vagino-cervical angle (VCA), strain elastography using the E-Cervix module, and cervical length (CL)). All selected parameters were characterized by good to excellent repeatability (intraclass correlation coefficient (ICC) = 0.878-0.994) and reproducibility (ICC = 0.826-0.996). Each of the selected parameters significantly correlated with its corresponding BS axis. The highest value of the correlation coefficient was achieved with CL (-0.75) and DL (0.71). Other parameters were characterized by an average to high correlation (AoP and station = 0.69, hardness ratio and consistency = -0.33, position and VCA = -0.38). The best correlation with the sum of the BS points was exhibited by AoP (0.52) and CL (-0.61). The selected ultrasound parameters analogous to the BS axes were characterized by high repeatability and significant correlation with the axes of the original clinical BS. Further research into the predictive properties of a multivariate model based on these parameters is needed.

Predictors of efficacy for cervical ripening among the Bishop score criteria in nulliparous women at term

OBJECTIVE

To determine predictors of efficacy for cervical ripening among the Bishop score criteria in nulliparous women at term.

METHOD

Prospective observational study of nulliparous women with singleton term fetuses in vertex presentation, intact membranes, and an unfavorable cervix (Bishop score < 6) who underwent cervical ripening with a cervical-ripening balloon (CRB; n = 47) or dinoprostone vaginal insert (PG; n = 28). The authors analyzed Bishop score criteria (dilatation, effacement, fetal station, consistency, position) before and after device removal. Primary outcome was favorable cervix (Bishop score ≥ 6) after device removal. Secondary outcomes were vaginal delivery, modification of Bishop score criteria, and perinatal morbidity.

RESULTS

Rates of favorable cervix after cervical ripening were similar between groups (66.7% with CRB vs. 59.3% with PG; P = 0.526). Vaginal delivery (76.6% vs. 78.6%; P = 0.843) and perinatal morbidity did not differ between groups. CRB appeared to be more effective than PG in increasing consistency (+0.7 ± 0.2 vs. +0.3 ± 0.2; P = 0.001) and dilatation of the cervix (+1.3 ± 0.3 vs. +0.9 ± 0.3; P = 0.005). No Bishop score criterion was found as a significant predictor for vaginal delivery.

CONCLUSION

CRB seems to be more effective than PG in increasing the consistency and dilatation of the cervix. Efficacy of CRB and PG for vaginal delivery was similar.

Development and Validation of a Nomogram to Estimate Risk of Cesarean After Induction of Labor in Term Pregnancies with an Unfavorable Cervix in Iran

This study aimed to develop and validate a labor induction nomogram for nulliparous and multiparous women who were 38 weeks pregnant or more and had their labor induced by an unfavorable cervix. This prospective study was conducted on 300 individuals (200 for nomogram development and 100 for nomogram validation). Height, body mass index at delivery, parity, gestational age, adjusted bishop score, and cesarean section risk assessment were all recorded on a checklist. Participants were followed until they gave birth, and the type of delivery was noted in the checklist. Out of 300 labor inductions, 80 (26.7%) underwent a cesarean section. Cesarean risk estimation was the only predictor of delivery type based on multivariate logistic regression. The AUC (Area Under the Curve) in development group was 0.68 and in validation group was 0.71. The developed nomogram for predicting of cesarean section risk following labor induction has a relatively good predictive value among women.

Proportion and Outcome of Induction of Labor Among Mothers Who Delivered in Teaching Hospital, Southwest Ethiopia

Background: Despite the induction of labor (IOL) having had some undesired consequences, it also has several benefits for maternal and perinatal outcomes. This study aimed to assess the proportion and outcome of IOL among mothers who delivered in Teaching Hospital, southwest Ethiopia.

Methods: A retrospective cross-sectional study was conducted from June 10 to June 20, 2019, among 294 mothers who gave birth between November 30, 2018, and May 30, 2019, by reviewing their cards using a structured checklist to assess the prevalence, outcome, and consequences of induction of labor. A binary logistic regression analysis was computed to look for the association between outcome variables and independent variables.

Results: The prevalence of labor induction was 20.4%. The most commonly reported cause of induction was preeclampsia (41.6%). The factors associated with IOL were mothers aged 25–34 years [AOR = 2.55, 95% CI (1.18–5.50)] and ≥35 years [AOR = 10.6, 95% CI (4.20–26.9)], having no history of antenatal care [AOR = 2.12, 95% CI (1.10–4.07)], and being Primipara AOR = 2.33, 95% CI (1.18–3.24)]. Of the 60 induced mothers, 23.3% had failed induction. The proportion of mothers with dead fetal outcomes and maternal complications was 5 and 41.7%, respectively. The unfavorable Bishop Score before induction [AOR = 1.85, 95% CI (1.32–4.87)] and induction using misoprostol [AOR = 1.48, 95% CI (1.24–5.23)] were the factors associated with failed induction of labor.

Conclusion: The prevalence of induced labor was considerably higher than rates in other Ethiopian studies; however, the prevalence of induction failure was comparable to other studies done in Ethiopia. The study found that Bishop's unfavorable score before induction and induction using misoprostol was the factor associated with unsuccessful induction. Therefore, the health professionals should confirm the favorability of the cervical status before the IOL to increase the success rate of induction of labor.

Evening primrose oil for cervical ripening in term pregnancies: a systematic review and meta-analysis

Induction of labor by using available, inexpensive and non-invasive methods with the least side effects is particularly important. A systematic review was conducted to assess the effect of evening primrose oil on cervical ripening in term pregnancies. In this systematic review and meta-analysis of clinical trials, a search was carried out in PubMed, Cochrane Library, Embase, Ovid, Scopus, Clinical Trials.gov, Google Scholar and Persian databases (Magiran, SID, and IRCT.ir) for published related articles without any time limit. The Cochrane handbook was used to determine the risk of bias of the included articles. The obtained data were analyzed in RevMan and reported in forest plots. The Odds Ratio (OR) was used to find the effect of the dichotomous data and the Mean Difference (MD) for the continuous data. The heterogeneity of the studies was assessed using I², T² and Chi². The random effect was used instead of fixed effect if I² >40%. A total of 28 titles and abstracts were extracted, 9 articles entered into the meta-analysis. The meta-analysis results showed significant differences between EPO and control groups in terms of bishop score (MD=1.32; 95% CI: 0.98 to 1.66), reducing caesarean section rate (OR= 0.61; 95% CI: 0.43 to 0.86), duration of first stage of labor (MD= -98.67; 95% CI: -140.98 to -56.38) and duration of second stage of labor (MD= -10.98; 95% CI: -21.86 to -0.09). There were no significant differences in terms of birth weight (MD= 100.97; 95% CI: -11.91 to 213.84) and the frequency of induction with oxytocin (OR= 0.53; 95% CI: 0.27 to 1.01). It seems evening primrose oil be effective for cervical ripening, reducing cesarean section rate and shortening the duration of labor. Due to the high heterogeneity of the studies, the researchers recommend further researches on the subject using a standard tool based on the CONSORT statement.

The Uterocervical Angle Combined with Bishop Score as a Predictor for Successful Induction of Labor in Term Vaginal Delivery

The objective of this study was to determine the value of uterocervical angle (UCA) in predicting successful induction of labor (IOL) in singleton pregnant women compared to the Bishop score and cervical length (CL). A total of 205 normal term, singleton labor-induction cases were analyzed. Successful IOL was defined as the onset of active labor of induction. A comparative analysis was performed to evaluate the effectiveness of UCA, Bishop score, and CL in predicting IOL. Compared to the non-successful IOL group, the women in the successful IOL group had significantly wider UCA (p = 0.012) and higher Bishop score (p = 0.001); however, the CL was not significantly different (p = 0.130). UCA alone did not perform better than the Bishop score when predicting successful IOL. However, UCA combined with the Bishop score showed higher performance in predicting IOL (combined UCA > 108.4° and favorable Bishop score as sensitivity of 44.6%, specificity of 96.0%, PPV of 96.2%, and NPV of 43.6; combined UCA > 108.4° or favorable Bishop score as sensitivity of 85.7%, specificity of 50.0%, PPV of 78.7%, and NPV of 61.9). In conclusion, UCA combined with Bishop score may be an effective sonographic method for predicting successful IOL.

Clinical application of low-dose misoprostol in the induced labor of 16 to 28 weeks pathological pregnancies (a STROBE-compliant article)

Oral mifepristone combined with rivanol lactate (rivanol) is commonly used in second-trimester pregnancy termination. However, rivanol is not suitable to premature rupture of membranes and oligohydramnios because amniocentesis is difficult. Mifepristone combined with misoprostol is suitable for the patients with oligohydramnios. In accordance with the misoprostol dosing recommendations by the International Federation of Gynecology and Obstetrics (FIGO), the incidences of uterine rupture and cervical laceration are relatively high in Chinese pregnant women. The aim of our study was to optimize misoprostol dosing regimen in terms of efficacy and safety in Chinese pregnant women.We modified the Bishop Score, and then gave patients low-dose misoprostol according to the modified Bishop score. Based on the amniotic fluid volume (AFV) indicated by type-B ultrasonic instrument, the cases with AFV ≤2 cm receiving low-dose misoprostol combined with mifepristone and the cases with amniocentesis failure followed by receiving low-dose misoprostol combined with mifepristone were enrolled into study group, and the cases with AFV >2 cm receiving rivanol combined with mifepristone were enrolled into control group. The start time of uterine contractions, time of fetal expulsion, birth process, hospital day, successful induced labor rate, complete induced labor rate, and incomplete induced labor rate were observed and compared between the 2 groups.There were significant differences in the start time of uterine contractions, time of fetal expulsion, birth process, and hospital day between the control group and the study group (all P < .05). The successful induced labor rate, complete induced labor rate, and incomplete induced labor rate were also significantly different between the 2 groups (all P < .05).In the induced labor of 16 to 28 weeks pathological pregnancy, low-dose misoprostol can markedly improve the successful induced labor rate and complete induced labor rate, shorten the birth process and hospital day, and decrease uterine curettage rate and uterine rupture risk. Low-dose misoprostol combined with mifepristone is suitable to the induced labor of 16 to 28 weeks pathological pregnancy in Chinese women.

Study of effects of mifepristone on full-term pregnancies

The induction of labour is required for various indications in obstetrics. Various regimens and drugs are advocated for use in labour induction. Mifepristone is one such drug which has a definite role in first and second-trimester pregnancy terminations. However, its role in the third-trimester is still being reviewed. In the present study, the effect of mifepristone on cervical ripening was assessed and results interpreted.Impact statementWhat is already known on the subject? The role of mifepristone in termination of pregnancies at term is controversial. Some studies report onset of labour after giving mifepristone whereas others do not report any significant role.What do the results of the study add? Mifepristone has a role in improving Bishop score and can be used as a pre-induction cervical ripening agent before using other methods for labour induction. It does not report any adverse effects on the mother or foetus.What are the implications of these findings for clinical practice and/or further research? Mifepristone needs to be studied more in term pregnancies as induction of labour is increasingly required in today's scenario for various reasons. However, its role in improving the Bishop score as found in this study helps in decreasing dose of other labour inducing agents.

Should cervical favourability play a role in the decision for labour induction in gestational hypertension or mild pre-eclampsia at term? An exploratory analysis of the HYPITAT trial

OBJECTIVE

To examine whether cervical favourability (measured by cervical length and the Bishop score) should inform obstetricians' decision regarding labour induction for women with gestational hypertension or mild pre-eclampsia at term.

DESIGN

A post hoc analysis of the Hypertension and Pre-eclampsia Intervention Trial At Term (HYPITAT).

SETTING

Obstetric departments of six university and 32 teaching and district hospitals in the Netherlands.

POPULATION

A total of 756 women diagnosed with gestational hypertension or pre-eclampsia between 36 + 0 and 41 + 0 weeks of gestation randomly allocated to induction of labour or expectant management.

METHODS

Data were analysed using logistic regression modelling.

MAIN OUTCOME MEASURES

The occurrence of a high-risk maternal situation defined as either maternal complications or progression to severe disease. Secondary outcomes were caesarean delivery and adverse neonatal outcomes.

RESULTS

The superiority of labour induction in preventing high-risk situations in women with gestational hypertension or mild pre-eclampsia at term varied significantly according to cervical favourability. In women who were managed expectantly, the longer the cervix the higher the risk of developing maternal high-risk situations, whereas in women in whom labour was induced, cervical length was not associated with a higher probability of maternal high-risk situations (test of interaction P = 0.03). Similarly, the beneficial effect of labour induction on reducing the caesarean section rate was stronger in women with an unfavourable cervix.

CONCLUSION

Against widely held opinion, our exploratory analysis showed that women with gestational hypertension or mild pre-eclampsia at term who have an unfavourable cervix benefited more from labour induction than other women.

TRIAL REGISTRATION

The trial has been registered in the clinical trial register as ISRCTN08132825.

Clinical parameters for prediction of successful labor induction after application of intravaginal dinoprostone in nulliparous Chinese women

BACKGROUND

The aim of this study was to compare the possible clinical parameters for prediction of successful labor induction in Chinese nulliparous women.

MATERIAL/METHODS

A retrospective, observational trial of labor induction was performed, using a single dose of 10 mg controlled-release dinoprostone for preinduction cervical ripening in 127 nulliparous women (gestational age 38-42 weeks, singleton cephalic presentation). The characteristics of the women with successful labor induction (defined as vaginal delivery achieved on the day of admission; n=80) and failed labor induction (n=47) were compared.

RESULTS

The main differences observed between the groups were gravidity (P<0.05), induction-active labor interval (5.16±2.98 vs. 8.40±3.41; P<0.05) and birth weight (3421.11±368.14 vs. 3566.36±345.16; P<0.05). Logistic regression demonstrated that gravidity (P<0.05) and induction-active labor interval (P<0.05), but not Bishop score, were significant and independent contributing factors for successful labor induction. In the receiver operating characteristic curves for the prediction of successful labor induction, the best cut-off value for gravidity was 3 (95% confidence interval [CI] 0.64-0.83, P=0.000), and the best cut-off value for the induction-active labor interval was 7.96 (95%CI 0.66-0.85, P=0.000).

CONCLUSIONS

Less gravidity and shorter induction-active labor interval predict successful labor induction with reasonable accuracy.

Transvaginal ultrasonographic cervical measurement in predicting failed labor induction and cesarean delivery for failure to progress in nulliparous women

The aim of this study was to evaluate the value of transvaginal sonographic cervical measurement in predicting failed labor induction and cesarean delivery for failure to progress in nulliparous women. One hundred and sixty-one women scheduled for labor induction underwent transvaginal ultrasonography and digital cervical examinations. Logistic regression demonstrated that cervical length and gestational age at induction, but not the Bishop score, significantly and independently predicted failed labor induction. According to the receiver operating characteristic curves analysis, the best cut-off value of cervical length for predicting failed labor induction was 28 mm, with a sensitivity of 62% and a specificity of 60%. In terms of the likelihood of a cesarean delivery for failure to progress as the outcome variable, logistic regression indicated that maternal height and birth weight, but not cervical length or Bishop score, were significantly and independently associated with an increased risk of cesarean delivery for failure to progress. Transvaginal sonographic measurements of cervical length thus independently predicted failed labor induction in nulliparous women. However, the relatively poor predictive performance of this test undermines its clinical usefulness as a predictor of failed labor induction. Moreover, cervical length appears to have a poor predictive value for the likelihood of a cesarean delivery for failure to progress.