Cervical length and maternal factors in expectantly managed prolonged pregnancy: prediction of onset of labor and mode of delivery

The predictive value of transvaginal cervical length and cervical angle ultrasonography in term delivery outcomes: a cohort study

BACKGROUND

Various techniques have been proposed to predict and evaluate the timing and conditions of childbirth in pregnant women at different stages of pregnancy. Providing precise methods for forecasting childbirth status can reduce the burden on the healthcare system. This study aimed to evaluate the predictive value of transvaginal sonography of cervical length (CL) and cervical angle (CA) on full-term delivery outcomes.

METHODS

This cohort study analyzed 151 pregnant women between 37 and 42 weeks of gestational age who were treated at Rasoul Akram Hospital affiliated with Iran University of Medical Sciences from June 2023 to January 2024. All Participants received transvaginal examinations. This study evaluated the accuracy of CL and CA by transvaginal sonography in predicting outcomes like vaginal delivery, cesarean section, necessity for labor induction, and the rate of Premature Rupture of Membranes (PROM). The study used the Receiver Operating Characteristic (ROC) curve to determine the optimal cutoff for predicting birth outcomes.

RESULTS

The mean age of the pregnant women was 28.9 ± 4.22 years, while the average duration of pregnancy was 39.8 ± 2.11 weeks. Cesarean delivery was performed on 45 individuals (29.8%) and 106 (70.1%) underwent vaginal delivery. The mean CL overall stood at 21.2 ± 6.4 mm. PROM was observed in 41 cases (27.1%) among full-term pregnancies. A significant difference was noted in mean CL between the cesarean and vaginal delivery groups (24.2 ± 2.4 vs. 20.1 ± 2.1 mm, p = 0.001). The predictive value of a CL measuring 21 mm for cesarean delivery was 72.2% sensitive and 79.1% specific. Similarly, a CL of 22 mm showed 66.6% sensitivity and 80.2% specificity for labor induction. Regarding PROM in full-term pregnancies, a CL assessment demonstrated 59.8% sensitivity and 69.1% specificity. Finally, a CA of 115.2° exhibited 70.3% sensitivity and 78.4% specificity in predicting vaginal delivery.

CONCLUSION

The present study showed that evaluating CL and CA via transvaginal sonography demonstrated adequate diagnostic accuracy in predicting spontaneous birth, need for labor induction, cesarean delivery, and incidence of PROM in full-term pregnant women. This method is suggested to be an accurate and appropriate way to predict delivery results.

Predicting Spontaneous Labor beyond 39 Weeks among Low-Risk Expectantly Managed Pregnant Patients

OBJECTIVES

The aim of the study was to identify the characteristics associated with spontaneous labor onset in pregnant patients undergoing expectant management at greater than 39 weeks' gestation and delineate perinatal outcomes associated with spontaneous labor compared with labor induction.

STUDY DESIGN

This was a retrospective cohort study of singleton pregnancies at ≥390/7 weeks' gestation delivered at a single center in 2013. The exclusion criteria were elective induction, cesarean delivery or presence of a medical indication for delivery at 39 weeks, more than one prior cesarean delivery, and fetal anomaly or demise. We evaluated prenatally available maternal characteristics as potential predictors of the primary outcome-spontaneous labor onset. Multivariable logistic regression was used to generate two parsimonious models: one with and one without third trimester cervical dilation. We also performed sensitivity analysis by parity and timing of cervical examination, and compared the mode of delivery and other secondary outcomes between patients who went into spontaneous labor and those who did not.

RESULTS

Of 707 eligible patients, 536 (75.8%) attained spontaneous labor and 171 (24.2%) did not. In the first model, maternal body mass index (BMI), parity, and substance use were identified as the most predictive factors. Overall, the model did not predict spontaneous labor (area under the curve [AUC]: 0.65; 95% confidence interval [CI]: 0.61-0.70) with high accuracy. The addition of third trimester cervical dilation in the second model did not significantly improve labor prediction (AUC: 0.66; 95% CI: 0.61-0.70; p = 0.76). These results did not differ by timing of cervical examination or parity. Patients admitted in spontaneous labor had lower odds of cesarean delivery (odds ratio [OR]: 0.33; 95% CI: 0.21-0.53) and neonatal intensive care unit (NICU) admission (OR: 0.38; 95% CI: 0.15-0.94). Other perinatal outcomes were similar between the groups.

CONCLUSION

Maternal characteristics did not predict spontaneous labor onset at ≥39 weeks' gestation with high accuracy. Patients should be counseled on the challenges of labor prediction regardless of parity and cervical examination, outcomes if spontaneous labor does not occur, and benefits of labor induction.

KEY POINTS

· Majority of patients will attain spontaneous labor at ≥39 weeks.. · Maternal characteristics do not predict labor at ≥39 weeks.. · Spontaneous labor has associated lower perinatal risks.. · A shared decision model should be utilized in counseling patients who may choose expectant management..

Fetal Movement Counting in Prolonged Pregnancies: The COMPTAMAF Prospective Randomized Trial

In prolonged pregnancies, the risks of neonatal morbidity and mortality are increased. The aim of this trial was to assess the benefits of maternal information about fetal movement (FM) counting on neonatal outcomes in prolonged pregnancy. It was a prospective, single center, randomized, open-label study conducted from October 2019 to March 2022. Intention-to-treat analyses were performed on 278 patients randomized into two 1:1 groups (control group and FM counting group). The primary outcome was a composite score of neonatal morbidity (presence of two of the following items: fetal heart rate abnormality at delivery, Apgar score of <7 at 5 min, umbilical cord arterial pH of <7.20, and acute respiratory distress with mutation in neonatal intensive care unit). There was no significant difference between the two groups in the rate of neonatal morbidity (14.0% in the FM counting group versus 22.9% in the standard information group; p = 0.063; OR 0.55, 95% CI 0.29−1.0). In this study, fetal movement counting for women in prolonged pregnancy failed to demonstrate a significant reduction in adverse neonatal outcomes.

Prediction of spontaneous onset of labor at term (PREDICT study): Research protocol

Background

Recent studies have shown that elective induction of labor versus expectant management after 39 weeks of pregnancy result in lower incidence of perinatal complications, while the proportion of cesarean deliveries remains stable, or even decreases. Still, evidence regarding collateral consequences of the potential increase of induction of labor procedures is still lacking. Also, the results of these studies must be carefully interpreted and thoroughly counter-balanced with women’s thoughts and opinions regarding the active management of the last weeks of pregnancy. Therefore, it may be useful to develop a tool that aids in the decision-making process by differentiating women who will spontaneously go into labor from those who will require induction.

Objective

To develop a predictive model to calculate the probability of spontaneous onset of labor at term.

Methods

We designed a prospective national multicentric observational study including women enrolled at 39 weeks of gestation, carrying singleton pregnancies. After signing an informed consent form, several clinical, ultrasonographic, biophysical and biochemical variables will be collected by trained staff. If delivery has not occurred at 40 weeks of pregnancy, a second visit and evaluation will be performed. Prenatal care will be continued according to current hospital guidelines. Once recruitment is completed, the information gathered will be used to develop a logistic regression-based predictive model of spontaneous onset of labor between 39 and 41 weeks of gestation. A secondary exploration of the data collected at 40 weeks, as well as a survival analysis regarding time-to-delivery outcomes will also be performed. A total sample of 429 participants is needed for the expected number of events.

Conclusion

This study aims to develop a model which may help in the decision-making process during follow-up of the last weeks of pregnancy.

Trial registration

NCT05109247 (clinicaltrials.gov).

Nulliparous women with an unfavourable cervix at 41 weeks: Which women go into spontaneous labor during the expectant period?

CONTEXT

After 41 weeks, the labor induction term varies according to countries and obstetrical teams. The French recommendations are not to exceed 41 weeks 6 days. However, there are no data on the percentage of nulliparous women with an unfavorable cervix at 41 weeks going into spontaneous labor within five or six days.

OBJECTIVE

The objective was to establish the rate of spontaneous labor within five days amongst nulliparous women with an unfavorable cervix at 41 weeks, and to identify the maternal and obstetrical factors associated with this spontaneous labor.

MATERIALS AND METHODS

Retrospective study in a University Hospital Maternity between January 1st and December 31st 2017. All nulliparous women with a cephalic fetal presentation and unfavorable cervix at 41 weeks (Bishop ≤ 3) were included. The maximum term for induced labor was set at 41 weeks 5 days. The population was divided into two groups: spontaneous labor and induced labor (induction between 41 weeks and 41 weeks 4 days for medical indications or maternal wish and induction at 41 weeks 5 days for full term). The maternal and obstetrical characteristics of the two groups at 41 weeks were compared as well as the maternal and neonatal outcomes.

RESULTS

The rate of spontaneous labor among the 269 women included was 38.3% (n = 103/269). At 41 weeks, the presence of painful uterine contractions and a Bishop score of 3 were associated with spontaneous labor within five days (p < 0.01). The Bishop score criteria most associated with spontaneous labor were cervical dilation and fetal station. The cesarean delivery rate was 20.4% in the group of women with spontaneous labor versus 41.0% in the group of induced labor (p < 0.01). There were no differences between the two groups in terms of neonatal outcome.

CONCLUSION

Among nulliparous women with an unfavorable cervix at 41 weeks, almost 40 % will have a spontaneous onset of labor within five days. The only factors found to be associated with this onset of labor are the presence of painful uterine contractions and a higher Bishop score at 41 weeks.

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

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

The 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 impact of preconception body mass index on cervical length: a prospective cohort study in China

Objective: To assess the relationship between preconception body mass index (BMI) and cervical length (CL).Methods: Data was collected from a prospective cohort study conducted in Beijing, China. A total of 4843 qualified women participated in this study, whose health-related information was recorded at the very beginning and their cervical length was measured with transvaginal ultrasound examination during 22-24 gestational weeks. Logistic regression was used to evaluate the relationship between preconception BMI and cervical length, after adjusting for potential confounders.Results: Of all the participants in the analysis, 580 (12.0%) women had a short cervical length (CL less than 30 mm). After adjusting for the age and parity status, the adjusted odds ratios of short CL for underweight: adjusted OR = 1.28 (95% CI: 1.02, 1.60); overweight: adjusted OR = 0.74 (95% CI: 0.55, 0.99); obesity: adjusted OR = 0.38 (95% CI: 0.17, 0.88) compared with normal weight. The mean CL in underweight, normal weight, overweight and obesity group demonstrated a significant linear increased trend (33.47, 34.16 and 34.96 mm, respectively) (p < .05), dependent of age and parity.Conclusions: This research revealed that low preconception BMI women were more likely to have a short CL.

Uterocervical angle: an ultrasound screening tool to predict satisfactory response to labor induction

Background: A wide uterocervical angle >95° detected during the second trimester was associated with an increased risk for spontaneous preterm birth.Objective: We aimed to determine whether an ultrasonographic marker, uterocervical angle, correlates with satisfactory response to labor induction.Study design: We conducted a prospective cohort study from May 2016 through December 2017 of singleton term gestations undergoing transvaginal ultrasound for cervical length screening and uterocervical angle measurement. Uterocervical angle was measured between the lower uterine segment and the cervical canal. Latent phase duration >720 min was accepted to be a prolonged latent phase. The primary outcome was a prediction of satisfactory response to labor induction (latent phase duration <720 min).Results: Both anterior uterocervical angle (AUC = 0.802, p < .001) and the cervical length (AUC = 0.679, p < .05) significantly predicted satisfactory response to labor induction. Optimal cutoff value was obtained at the value of 97° (64% sensitivity, 91% specificity) for anterior uterocervical angle and 27 mm (64% sensitivity, 64% specificity) for the cervical length. Kaplan-Meier survival analysis showed that duration from labor induction to delivery was significantly higher in a group with longer cervical length (p = .04), additionally labor induction to delivery time was significantly higher in a group with lower UCA (p = .04).Conclusions: Both the cervical length and anterior uterocervical length were predictors for the satisfactory response to labor induction, and both parameters were found to be significantly associated with time from induction to delivery in survival analysis.

Is ultrasound measured fetal biometry predictive of intrapartum caesarean section for failure to progress?

BACKGROUND

There are global concerns regarding excessive caesarean rates, which could be reduced by identification of risk factors leading to preventative measures such as induction of labour.

AIMS

This study aims to describe the association between antenatal ultrasound and emergency caesarean section for: (i) failure to progress; (ii) other indications; and (iii) any indication.

MATERIALS AND METHODS

Women who had an ultrasound in pregnancy between 36^(+0/7) to 38^(+6/7) weeks at Royal Prince Alfred Hospital from January 2005 to June 2009 were included. Ultrasound parameters were linked to clinical parameters from the maternity database. Missing clinical data were imputed and multiple logistic regression performed.

RESULTS

Fetal biometry data were available for 2006 pregnancies. After adjusting for maternal age, height, body mass index, parity, previous caesarean section and diabetes, caesarean section for failure to progress was associated with estimated fetal weight (odds ratio (OR) 2.24 (95% CI: 1.76-2.84) per 500 g increase); or biparietal diameter (OR 1.51 (1.16-1.97) per 5 mm increase) and abdominal circumference (OR for the 4th quartile (>75th centile) compared with the 10-25th centile group was 2.09 (1.13-3.85)).* There were also non-linear associations between components of fetal biometry and caesarean section for fetal distress and for any indication.

CONCLUSIONS

Components of fetal biometry in the third trimester are associated with intrapartum caesarean section for failure to progress. These parameters could be incorporated into models to predict emergency caesarean section which could lead to implementation of preventative strategies. *[Corrections added on 29 January 2018, after first online publication, '(OR for the 4th quartile (>7th centile)' has been changed to '(OR for the 4th quartile (>75th centile)'.].

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.

Prediction of labor onset type: Spontaneous vs induced; role of electrohysterography?

BACKGROUND AND OBJECTIVE

Induction of labor (IOL) is a medical procedure used to initiate uterine contractions to achieve delivery. IOL entails medical risks and has a significant impact on both the mother's and newborn's well-being. The assistance provided by an automatic system to help distinguish patients that will achieve labor spontaneously from those that will need late-term IOL would help clinicians and mothers to take an informed decision about prolonging pregnancy. With this aim, we developed and evaluated predictive models using not only traditional obstetrical data but also electrophysiological parameters derived from the electrohysterogram (EHG).

METHODS

EHG recordings were made on singleton term pregnancies. A set of 10 temporal and spectral parameters was calculated to characterize EHG bursts and a further set of 6 common obstetrical parameters was also considered in the predictive models design. Different models were implemented based on single layer Support Vector Machines (SVM) and with aggregation of majority voting of SVM (double layer), to distinguish between the two groups: term spontaneous labor (≤41 weeks of gestation) and IOL late-term labor. The areas under the curve (AUC) of the models were compared.

RESULTS

The obstetrical and EHG parameters of the two groups did not show statistically significant differences. The best results of non-contextualized single input parameter SVM models were achieved by the Bishop Score (AUC= 0.65) and GA at recording time (AUC= 0.68) obstetrical parameters. The EHG parameter median frequency, when contextualized with the two obstetrical parameters improved these results, reaching AUC= 0.76. Multiple input SVM obtained AUC= 0.70 for all EHG parameters. Aggregation of majority voting of SVM models using contextualized EHG parameters achieved the best result AUC= 0.93.

CONCLUSIONS

Measuring the electrophysiological uterine condition by means of electrohysterographic recordings yielded a promising clinical decision support system for distinguishing patients that will spontaneously achieve active labor before the end of full term from those who will require late term IOL. The importance of considering these EHG measurements in the patient's individual context was also shown by combining EHG parameters with obstetrical parameters. Clinicians considering elective labor induction would benefit from this technique.

Sonographical predictive markers of failure of induction of labour in term pregnancy

Predictive markers of failure of induction of labour in term pregnancy were evaluated. A prospective study including 245 women attending induction of labour was performed. The inclusion criteria were singleton pregnancies, gestational age 37-42 weeks and the main outcomes were failure of induction, induction to delivery interval and mode of delivery. Women with a longer cervical length prior to induction (CLpi) had a higher rate of failure of induction (30.9 ± 6.8 vs. 23.9 ± 9.3, p < .001). BMI was higher and maternal height was lower in the group of caesarean section compared to vaginal delivery (33.1 ± 8 vs. 29.3 ± 4.6, 160 ± 5 vs. 164 ± 5, p < .001, respectively). A shorter CLpi correlated with a shorter induction to delivery interval (R Pearson .237, p < .001). In the regression analysis, for failure of induction the only independent predictor was the CL prior to induction. Therefore, the CLpi is an independent factor for prediction of failure of induction of labour.

The use of cervical sonography to differentiate true from false labor in term patients presenting for labor check

BACKGROUND

Cervical length by transvaginal ultrasound to predict preterm labor is widely used in clinical practice. Virtually no data exist on cervical length measurement to differentiate true from false labor in term patients who present for labor check. False-positive diagnosis of true labor at term may lead to unnecessary hospital admissions, obstetrical interventions, resource utilization, and cost.

OBJECTIVE

We sought to determine if cervical length by transvaginal ultrasound can differentiate true from false labor in term patients presenting for labor check.

STUDY DESIGN

This is a prospective observational study of women presenting to labor and delivery with labor symptoms at 37-42 weeks, singleton cephalic gestation, regular uterine contractions (≥4/20 min), intact membranes, and cervix ≤4 cm dilated and ≤80% effaced. Those patients with placenta previa and indications for immediate delivery were excluded. The shortest best cervical length of 3 collected images was used for analysis. Providers managing labor were blinded to the cervical length. True labor was defined as spontaneous rupture of membranes or spontaneous cervical dilation ≥4 cm and ≥80% effaced within 24 hours of cervical length measurement. In the absence of these outcomes, labor status was determined as false labor. Receiver operating characteristic curves were generated to assess the predictive ability of cervical length to differentiate true from false labor and were analyzed separately for primiparous and multiparous patients. The diagnostic accuracies of various cervical length cutoffs were determined. The relationship of cervical length and time to delivery was also analyzed including both use and nonuse of oxytocin.

RESULTS

In all, 77 patients were included in the study; the prevalence of true labor was 58.4% (45/77). Patients who were in true labor had shorter cervical length as compared to those in false labor: median 1.3 cm (range 0.5-4.1) vs 2.4 cm (range 1.0-5.0), respectively (P < .001). The area under the receiver operating characteristic curve for primiparous patients was 0.88 (P < .001) and for multiparous patients was 0.76 (P < .01), both demonstrating good correlation. The area under the receiver operating characteristic curves were not significantly different between primiparous and multiparous (P = .23). The area under the receiver operating characteristic curve for primiparous and multiparous patients combined was 0.8 (P < .0001), indicating a good overall correlation between cervical length and its ability to differentiate true from false labor. Overall, a cervical length cutoff of ≤1.5 cm to predict true labor had the highest specificity (81%), positive predictive value (83%), and positive likelihood ratio (4.2). There were no differences in cervical length prediction between primiparous and multiparous patients. Cervical length was positively correlated with time to delivery, regardless of the use of oxytocin.

CONCLUSION

In differentiating true from false labor in term patients who present for labor check, a cervical length of ≤1.5 cm was the most clinically optimal cutoff with the lowest false positive rate-due to its highest specificity-and highest positive predictive value and positive likelihood ratios. Its use to decide admission in patients at term with labor symptoms may prevent unnecessary admissions, obstetrical interventions, resource utilization, and cost.

Ultrasound examination at term for predicting the outcome of delivery in women with a previous cesarean section

OBJECTIVE

To evaluate if ultrasound variables at term are associated with the mode of delivery in women with previous cesarean section (PCS).

METHODS

This was a prospective study of singleton pregnant women who planned a trial of vaginal birth after cesarean delivery. Cervical length, posterior cervical angle, head-perineum distance, and estimated fetal weight were measured at 37-39 weeks of gestation.

RESULTS

One hundred forty-four pregnancies were examined and vaginal delivery was achieved in 98 women (73%). Logistic regression analysis identified cervical length, head-perineum distance, age, previous vaginal delivery, previous cesarean for dystocia, and Bishop score as predictors of vaginal delivery. Combining ultrasound and clinical parameters, two models for risk scoring that differ in the variable Bishop score or cervical length were constructed. The AUC of these models was 0.867 and 0.855, respectively.

CONCLUSIONS

In women with a PCS, measurement of cervical length and head-perineum distance at term is associated with the mode of delivery. A combination of clinical and sonographic parameters at term can predict the likelihood of vaginal delivery.

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.

Association between levator hiatal dimensions on ultrasound during first pregnancy and mode of delivery

OBJECTIVES

To determine the association between levator hiatal dimensions, measured using transperineal ultrasound, in women during their first pregnancy and the subsequent mode of delivery, stratified by the indication for intervention.

METHODS

In this prospective observational study, 280 nulliparous women with a singleton pregnancy were invited for transperineal ultrasound examination at 12 and 36 weeks' gestation. Their levator hiatal dimensions were measured at rest, on pelvic floor muscle contraction and on Valsalva maneuver. The subsequent mode of delivery was classified into five categories: spontaneous vaginal delivery, instrumental vaginal delivery owing to fetal distress, instrumental vaginal delivery owing to failure to progress, Cesarean section owing to fetal distress and Cesarean section owing to failure to progress. Levator hiatal dimensions according to mode of delivery were compared by analysis of variance and Tukey's post-hoc test. Since multiple comparison tests were performed, the statistical significance level was corrected using the Bonferroni method.

RESULTS

Of the 252 women included, those who delivered by Cesarean section because of failure to progress had a significantly smaller levator hiatal transverse diameter on pelvic floor contraction at 12 weeks' gestation than did women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P < 0.001). There was also a trend towards a smaller hiatal area on pelvic floor contraction at 12 weeks' gestation in women who delivered by Cesarean section because of failure to progress compared to women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P = 0.005). In women who had an instrumental vaginal delivery because of failure to progress there was a trend towards a smaller levator hiatal anteroposterior diameter on pelvic floor contraction at 36 weeks' gestation compared with women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P = 0.033).

CONCLUSIONS

Smaller levator hiatal dimensions on pelvic floor contraction during first pregnancy are associated with a subsequent instrumental vaginal delivery or a Cesarean section owing to failure to progress.

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.

Association between second-trimester cervical length and cesarean delivery in multiparas

OBJECTIVES

The purpose of this study was to determine whether there is an association between second-trimester cervical length and cesarean delivery in women with a prior vaginal delivery.

METHODS

We conducted a retrospective cohort study of multiparous women with singleton gestations who underwent routine cervical length screening between 18 and 24 weeks' gestation and labored after 34 weeks. Cervical lengths were divided into quartiles, and the frequency of cesarean delivery was compared across the groups. Indications for cesarean delivery were also compared. A multivariable logistic regression was performed with cervical length as a categorical and a continuous variable to adjust for potential confounders.

RESULTS

Of the 2260 multiparas who met inclusion criteria, 63 (2.8%) underwent a cesarean delivery. We observed no association between the second-trimester cervical length quartile and the frequency of cesarean delivery (2.1%, 3.5%, 2.3%, and 3.1%, respectively; P = .434). Further analysis using cervical length as a continuous variable and controlling for potential confounding variables did not change this result (adjusted odds ratio, 1.08; 95% confidence interval, 0.80-1.46).

CONCLUSIONS

The second-trimester cervical length quartile in multiparas is not associated with an increased frequency of cesarean delivery. This finding differs from studies of nulliparas.

Elastography in predicting preterm delivery in asymptomatic, low-risk women: a prospective observational study

Background

Despite the efforts to decrease the rate of preterm birth, preterm delivery is still the main cause of neonatal morbidity and mortality. Identifying patients threatened with preterm delivery remains one of the main obstetric challenges. The aim of this study was to estimate the potential value of elastographic evaluation of internal cervical os stiffness at 18-22 weeks of pregnancy in low risk, asymptomatic women in the prediction of spontaneous preterm delivery.

Methods

This prospective observational study included 333 low-risk, asymptomatic women presenting for the routine second trimester ultrasound scan according to the Polish Gynecological Society recommendation between 18-22 weeks of pregnancy. Ultrasound examinations of the cervix were performed transvaginally. The following data were recorded: elastographic color assessment of the internal os and ultrasound cervical length at 18-22 and 30 weeks of pregnancy; maternal age; obstetrical history; presence of cervical funneling at 30 weeks of pregnancy; gestational age at birth. Elastographic assessment of the internal os was performed using a color map: red (soft), yellow (medium soft), blue (medium hard) and purple (hard). If two colors were visible in the region of the internal os, the softer option was noted. Statistical analysis was performed using Statistica software (version 10, Statsoft Poland) using the following tests: chi square test to compare frequency of preterm deliveries in various categories of internal os assessment and Spearman correlation test to determine the correlation between elastographic assessment and cervical shortening. To determine the cut off category of internal os elastography assessment in selecting high preterm delivery risk patients we have calculated the sensivity, specifity, negative predictive value and positive predictive value.

Results

The number of preterm deliveries (<37 weeks of pregnancy) was significantly higher in the red and yellow groups, than in the blue and purple groups. The sensivity, specifity, NPV and PPV for both red and yellow internal os assessment in predicting preterm delivery were 85.7%, 97.6%, 98.3% and 81.1% respectively.

Conclusions

Elastographic assessment of the internal cervical os at 18-22 weeks of pregnancy may identify patients with high risk of preterm delivery in low-risk, asymptomatic women.

Can angle of progression in pregnant women before onset of labor predict mode of delivery?

OBJECTIVES

The angle of progression (AOP), measured by transperineal ultrasound, has been used to assess fetal head descent during labor. Our aim was to assess whether, before onset of labor, parous women have a narrower AOP than do nulliparous women and if a narrow AOP is associated with a higher rate of Cesarean delivery.

METHODS

In this prospective, observational study, we performed transperineal ultrasound in pregnant women not yet in labor at ≥ 39 weeks' gestation who delivered within 1 week of sonography. The AOP was compared as follows: in nulliparous women, between those who had a Cesarean section and those who delivered vaginally; and among women who delivered vaginally, between those who were nulliparous and those who were parous.

RESULTS

Included in the study were 100 nulliparous and 71 parous women. Among those who delivered vaginally (n = 161), the median AOP before onset of labor was narrower in parous than in nulliparous women (98° (interquartile range (IQR)), 90-107° vs 104° (IQR, 97-113°), P < 0.001). Among the 100 nulliparous women, (1) the median AOP before onset of labor was narrower in those who went on to deliver by Cesarean section (n = 9) than in those delivered vaginally (n = 91) (90° (IQR, 85.5-93.5°) vs 104° (IQR, 97-113°), P < 0.001); (2) an AOP ≥ 95° (derived from the receiver-operating characteristics curve) was associated with vaginal delivery in 99% of women; and (3) 89% (8/9) of women who delivered by Cesarean section had an AOP < 95°. Among the 71 parous women, only one delivered by Cesarean section and all of those with an AOP < 95° delivered vaginally.

CONCLUSION

A narrow AOP (< 95°) in non-laboring nulliparous women at term is associated with a high rate of Cesarean delivery. Parous women have a narrower AOP than do nulliparous women before the onset of labor; however, unlike in nulliparous women, a narrow AOP in parous women does not appear to be associated with Cesarean delivery and most parous women with such an angle go on to deliver vaginally.

Quantification of cervical elastography: a reproducibility study

OBJECTIVES

To assess a new method for numerical quantification of cervical elastography during pregnancy and to evaluate the repeatability of the measurements.

METHODS

Cervical elastography was carried out twice by a single operator in 112 singleton pregnancies at a median of 21 (range, 12-40) weeks' gestation. In 50 of the cases a second operator performed another elastography measurement. The intraobserver and interobserver repeatability of measurements in different parts of the cervix were assessed using intraclass correlation coefficients with 95% CI and by Bland-Altman analysis.

RESULTS

There were no statistically significant differences in the elastography measurements made by the same and by two different observers in each area measured, except in the area that receives the force of the transducer directly. The distribution of elastographic measurements obtained in different regions of the cervix demonstrated that the external and superior parts were significantly softer than the internal and inferior parts.

CONCLUSION

It is possible to provide an objective quantification of elastographic colors in the cervix. The measurements obtained by elastography may be a mere reflection of the force being applied by the transducer to different parts of the cervix. It is too premature to suggest that the measurements of rate-of-change in tissue displacement reflect histological changes that could provide a measure of cervical ripening.

Biochemical and biophysical predictors of the response to the induction of labor in nulliparous postterm pregnancy

OBJECTIVE

The objective of the study was to evaluate the clinical, sonographic, and hormonal variables that influence the success of labor induction in nulliparous postterm pregnancies.

STUDY DESIGN

Fifty nulliparous women with a single postterm pregnancy receiving a slow-release prostaglandin estradiol pessary were prospectively enrolled, and clinical characteristics were analyzed in relation to success of induction of labor. Clinical, sonographic, and hormonal variables were analyzed by univariate statistical analysis and multivariate logistic regression for the prediction of successful induction.

RESULTS

The group of patients delivering within 24 hours differed significantly from the remaining patients by higher Bishop scores, body mass indices, estradiol serum concentrations, estriol to estradiol ratios, and shorter cervices. The combination of cervical length and estriol to estradiol ratio achieved a sensitivity of 100% (95% confidence interval, 71.3-100%) and a specificity of 94.1% (95% confidence interval, 80.3-99.1%).

CONCLUSION

Cervical length and the estriol to estradiol ratio represent good predictive indicators of the response to the induction of labor in postterm pregnancies.

Guidelines for the management of postterm pregnancy

A pregnancy reaching 42 completed weeks (294 days) is defined as postterm (PT). The use of ultrasound in early pregnancy for precise dating significantly reduces the number of PT pregnancies compared to dating based on the last menstrual period. Although the fetal, maternal and neonatal risks increase beyond 41 weeks, there is no conclusive evidence that prolongation of pregnancy, per se, is the major risk factor. Other specific risk factors for adverse outcomes have been identified, the most important of which are restricted fetal growth and fetal malformations. In order to prevent PT and associated complications routine induction before 42 weeks has been proposed. There is no conclusive evidence that this policy improves fetal, maternal and neonatal outcomes as compared to expectant management. It is also unclear if the rate of cesarean sections is different between the two management strategies. After careful identification and exclusion of specific risks, it would seem appropriate to let women make an informed decision about which management they wish to undertake. There is consensus that the number of inductions necessary to possibly avoid one stillbirth is very high. If induction is preferred, procedures for cervical ripening should be used, especially in nulliparous women. Close intrapartum fetal surveillance should be offered, irrespective of whether labor was induced or not.

Ultrasonographic assessment of cervix size and its correlation with female characteristics, pregnancy, BMI, and other anthropometric features

PURPOSE

Cervical length during the first trimester of pregnancy has not been completely investigated yet. The objective of our study is to compare cervical size in the first ten gestational weeks with that of non-pregnant women, and to determine its correlation with maternal factors, including age, anthropometric features, and reproductive history.

METHODS

We collected retrospective data about women who applied to the Obstetrics and Gynecology Outpatients Facility of Udine between February and June 2009, selecting both pregnant and non-pregnant women possessing a transvaginal ultrasonographic measurement of their cervix, and focusing on their age, parity, BMI, cervical, and uterine size. Data were analyzed by R (version.2.8.0), considering significant P < 0.05.

RESULTS

135 women were recruited. By multivariate linear regression, both cervical length and width result independently influenced by pregnancy status, and among non-pregnant nullipara, cervical length results to be significantly lower in women younger than 20 (P < 0.05).

CONCLUSIONS

During the first ten gestational weeks, cervix results to be longer and wider than in non-pregnant women, suggesting the possible existence of early gestational, morphological, uterine, and cervical modifications. Women under the age of 20 have a significantly shorter cervix, suggesting an incomplete cervix maturity in this group of women, which may justify the higher prevalence of pre-term births in teenage pregnancies.