Head progression distance during the first stage of labor as a predictor for delivery outcome

2D-transperineal ultrasound in delivery room: Contribution in assessing labor progress, predicting outcome of labor and recognizing obstetric anal sphincter injuries (OASIS). A systematic review

AIMS

Ultrasound is used in the delivery room to assess fetal head position, engagement during labor, and anal sphincter injuries in the immediate postpartum period. The transperineal approach allows for direct visualization of the structures of interest without altering anatomical landmarks. Various ultrasound measurements during labor have been described in the literature, and their use varies widely across maternity units. Our objective was to conduct a systematic review of the literature on relevant ultrasound parameters for the management of labor and delivery.

MATERIAL AND METHODS

We reviewed articles indexed in MEDLINE from 1990 to 2022, selecting those that evaluated transperineal ultrasound during labor for term singleton fetuses in cephalic presentation.

RESULTS

We identified 124 articles out of 394 references, including 4 randomized controlled trials, 108 prospective studies, 6 cross-sectional studies, and 6 retrospective studies. The Angle of Progression (AOP) is better documented and appears more reliable than the Head-Perineum Distance (HPD) for diagnosing engagement, monitoring labor, and predicting its outcome. The HPD is easier to perform but shows inconsistencies in the literature. The Head Progression Distance (HPrD) shows good performance but requires further studies before routine use, as does Head-Symphysis Distance (HSD). Recent studies show a growing interest in ultrasound biofeedback of fetal head progression to improve pushing efforts as well as screening for Obstetrical Anal Sphincter Injuries (OASIS).

CONCLUSIONS

Transperineal ultrasound is a minimally invasive technique that can be used routinely in the delivery room. It can aid in monitoring labor, predicting the mode of delivery, and may serve as valuable biofeedback to optimize pushing during expulsion.

Serial intrapartum ultrasound to predict vaginal delivery using angle of progression and head- progression distance in term nulliparous women

INTRODUCTION

Over the past decade, intrapartum ultrasound (ITU) has been in the global limelight for labour monitoring. The use of the same in clinical settings of low- and middle-income countries (LMIC's) however, is limited. Till date, angle of progression (AOP) stands as the most studied parameter. Very few studies, most from developed countries, have shown that other ITU measurements could also hold relevance to labour and delivery. In recent times, serial ITU has also garnered some attention and could possibly be a better predictor of labour outcome.

AIMS

This study aimed to compare the predictive accuracies of AOP and head PD for vaginal delivery and to investigate whether the rate of change of serially measured AOP and head PD in the first stage is predictive of vaginal delivery.

METHODS

A prospective observational study was conducted on 90 nulliparous women between April 2023 and July 2024 at a tertiary teaching hospital in South India. Participants had singleton pregnancies in cephalic presentation between 37-40 weeks with regular contractions, and cervical dilation ≥ 3 cm. Exclusion criteria included prior LSCS and abnormal cardiotocography. Intrapartum ultrasound was performed twice, once at recruitment and 3-5 h apart, to measure AOP and PD. Statistical analysis included ROC curve plotting for diagnostic accuracy of AOP and PD in predicting vaginal delivery.

RESULTS

Of the 90 participants, 71 (78.9 %) delivered vaginally and 19 (21.1 %) had caesarean sections. AOP ≥ 120° and PD ≥ 2.7 cm at ≥ 6 cm cervical dilation showed a strong correlation with vaginal delivery, with sensitivity and specificity of 70.4 % and 94.7 %, and 63.4 % and 89.5 % respectively. Change (delta) in AOP > 10° had the highest diagnostic accuracy (81 %), with a positive predictive value of 92.2 %.

CONCLUSION

ITU offers valuable insights into labour progression. AOP and PD, particularly at cervical dilation of ≥ 6 cm, are predictive of vaginal delivery. Delta AOP serves as the most accurate predictor. Incorporating ITU into routine labour management enhances clinical decision-making, helping reduce unnecessary interventions and caesarean deliveries.

Inconsistent definitions of prolonged labor in international literature: a scoping review

Objective

Prolonged labor is the commonest indication for intrapartum cesarean section, but definitions are inconsistent and some common definitions were recently found to overestimate the speed of physiological labor. The objective of this review is to establish an overview of synonyms and definitions used in the literature for prolonged labor, separated into first and second stages, and establish types of definitions used.

Data sources

A systematic search was conducted in PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier.

Study eligibility criteria

All articles in English that (1) attempted to define prolonged labor, (2) included a definition of prolonged labor, or (3) included any synonym for prolonged labor, were included.

Methods

Data on study design, year of publication, country or region of origin, synonyms used, definition of prolonged first and/or second stage, and origin of provided definition (if not primarily established by the study) were collected into a database.

Results

In total, 3402 abstracts and 536 full-text papers were screened, and 232 papers were included. Our search established 53 synonyms for prolonged labor. Forty-three studies defined prolonged labor and 189 studies adopted a definition of prolonged labor. Definitions for prolonged first stage of labor were categorized into: time-based (n=14), progress-based (n=12), clinician-based (n=5), or outcome-based (n=4). For the 33 studies defining prolonged second stage, the majority of definitions (n=25) were time-based, either based on total duration or duration of no descent of the presenting part.

Conclusions

Despite efforts to arrive at uniform labor curves, there is still little uniformity in definitions of prolonged labor. Consensus on which definition to use is called for, in order to safely and respectfully allow physiological labor progress, ensure timely management, and assess and compare incidence of prolonged labor between settings.

Can assessing the angle of progression before labor onset assist to predict vaginal birth after cesarean?: A prospective cohort observational study

OBJECTIVE

To assess whether pre-labor measurement of the angle of progression (AOP) can assist in predicting a successful vaginal birth after cesarean in women without a previous vaginal birth.

METHODS

A prospective observational cohort study performed in a single tertiary center including women at term with a single previous cesarean delivery (CD), without prior vaginal births, who desire a trial of labor. Transperineal ultrasound was used to measure the AOP before the onset of labor. The managing staff in the delivery suite was blinded to the ultrasound measurements. Clinical data and delivery outcome were retrieved from medical records. The study was approved by the institutional ethics committee (KMC 0117-10).

RESULTS

Of the 111 women included in the study, 67 (60.4%) had a successful vaginal birth after CD. Women were sonographically assessed at a median of 3 days [interquartile range (IQR) 1-3 days] prior to delivery. The median AOP was significantly narrower in women who eventually underwent a CD than in those who delivered vaginally (88°, IQR 78-96° vs. 99°, IQR 89-107°, respectively; p < .001). An AOP >98° (derived from a receiver operating characteristic curve) was associated with a successful vaginal birth after CD in 87.5% of women. Multivariable regression analysis demonstrated that each additional 1° in the AOP increases the chance for a successful vaginal birth after CD by 6%.

CONCLUSIONS

Pre-labor AOP may be a useful sonographic tool for predicting vaginal birth after CD and can assist in consulting primiparous women with a prior CD opting for a trial of labor.

Routine vaginal examinations compared to other methods for assessing progress of labour to improve outcomes for women and babies at term

BACKGROUND

Routine vaginal examinations are undertaken at regular time intervals during labour to assess whether labour is progressing as expected. Unusually slow progress can be due to underlying problems, described as labour dystocia, or can be a normal variation of progress. Evidence suggests that if mother and baby are well, length of labour alone should not be used to decide whether labour is progressing normally. Other methods to assess labour progress include intrapartum ultrasound and monitoring external physical and behavioural cues. Vaginal examinations can be distressing for women, and overdiagnosis of dystocia can result in iatrogenic morbidity due to unnecessary intervention. It is important to establish whether routine vaginal examinations are effective, both as an accurate measure of physiological labour progress and to distinguish true labour dystocia, or whether other methods for assessing labour progress are more effective. This Cochrane Review is an update of a review first published in 2013.

OBJECTIVES

To compare the effectiveness, acceptability, and consequences of routine vaginal examinations compared with other methods, or different timings, to assess labour progress at term.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth Trials Register (which includes trials from CENTRAL, MEDLINE, Embase, CINAHL, and conference proceedings) and ClinicalTrials.gov (28 February 2021). We also searched the reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of vaginal examinations compared with other methods of assessing labour progress and studies assessing different timings of vaginal examinations. Quasi-RCTs and cluster-RCTs were eligible for inclusion. We excluded cross-over trials and conference abstracts.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed all studies identified by the search for inclusion in the review. Four review authors independently extracted data. Two review authors assessed risk of bias and certainty of the evidence using GRADE.

MAIN RESULTS

We included four studies that randomised a total of 755 women, with data analysed for 744 women and their babies. Interventions used to assess labour progress were routine vaginal examinations, routine ultrasound assessments, routine rectal examinations, routine vaginal examinations at different frequencies, and vaginal examinations as indicated. We were unable to conduct meta-analysis as there was only one study for each comparison.  All studies were at high risk of performance bias due to difficulties with blinding. We assessed two studies as high risk of bias and two as low or unclear risk of bias for other domains. The overall certainty of the evidence assessed using GRADE was low or very low.  Routine vaginal examinations versus routine ultrasound to assess labour progress (one study, 83 women and babies) Study in Turkey involving multiparous women with spontaneous onset of labour. Routine vaginal examinations may result in a slight increase in pain compared to routine ultrasound (mean difference -1.29, 95% confidence interval (CI) -2.10 to -0.48; one study, 83 women, low certainty evidence) (pain measured using a visual analogue scale (VAS) in reverse: zero indicating 'worst pain', 10 indicating no pain). The study did not assess our other primary outcomes: positive birth experience; augmentation of labour; spontaneous vaginal birth; chorioamnionitis; neonatal infection; admission to neonatal intensive care unit (NICU). Routine vaginal examinations versus routine rectal examinations to assess labour progress (one study, 307 women and babies) Study in Ireland involving women in labour at term. We assessed the certainty of the evidence as very low. Compared with routine rectal examinations, routine vaginal examinations may have little or no effect on: augmentation of labour (risk ratio (RR) 1.03, 95% CI 0.63 to 1.68; one study, 307 women); and spontaneous vaginal birth (RR 0.98, 95% CI 0.90 to 1.06; one study, 307 women). We found insufficient data to fully assess: neonatal infections (RR 0.33, 95% CI 0.01 to 8.07; one study, 307 babies); and admission to NICU (RR 1.32, 95% CI 0.47 to 3.73; one study, 307 babies). The study did not assess our other primary outcomes: positive birth experience; chorioamnionitis; maternal pain. Routine four-hourly vaginal examinations versus routine two-hourly examinations (one study, 150 women and babies) UK study involving primiparous women in labour at term. We assessed the certainty of the evidence as very low. Compared with routine two-hourly vaginal examinations, routine four-hourly vaginal examinations may have little or no effect, with data compatible with both benefit and harm, on: augmentation of labour (RR 0.97, 95% CI 0.60 to 1.57; one study, 109 women); and spontaneous vaginal birth (RR 1.02, 95% CI 0.83 to 1.26; one study, 150 women). The study did not assess our other primary outcomes: positive birth experience; chorioamnionitis; neonatal infection; admission to NICU; maternal pain. Routine vaginal examinations versus vaginal examinations as indicated (one study, 204 women and babies)  Study in Malaysia involving primiparous women being induced at term. We assessed the certainty of the evidence as low. Compared with vaginal examinations as indicated, routine four-hourly vaginal examinations may result in more women having their labour augmented (RR 2.55, 95% CI 1.03 to 6.31; one study, 204 women). There may be little or no effect on: • spontaneous vaginal birth (RR 1.08, 95% CI 0.73 to 1.59; one study, 204 women); • chorioamnionitis (RR 3.06, 95% CI 0.13 to 74.21; one study, 204 women); • neonatal infection (RR 4.08, 95% CI 0.46 to 35.87; one study, 204 babies); • admission to NICU (RR 2.04, 95% CI 0.63 to 6.56; one study, 204 babies). The study did not assess our other primary outcomes of positive birth experience or maternal pain.

AUTHORS' CONCLUSIONS

Based on these findings, we cannot be certain which method is most effective or acceptable for assessing labour progress. Further large-scale RCT trials are required. These should include essential clinical and experiential outcomes. This may be facilitated through the development of a tool to measure positive birth experiences. Data from qualitative studies are also needed to fully assess whether methods to evaluate labour progress meet women's needs for a safe and positive labour and birth, and if not, to develop an approach that does.

Intrapartum ultrasound in women with prolonged first stage of labor

The first stage of labor is from the start of active labor until the cervix is fully dilatated. To assess labor progress during this stage, a clinical examination has traditionally been done. The cervical dilatation, fetal head position, and fetal head station are evaluated. Moreover, these observations can be made with an ultrasound examination. Studies have shown that traditional clinical examinations are subjective, have poor reproducibility, and are unreliable. Ultrasound examinations of the fetal head station and fetal head position in the first stage of labor might predict labor outcome and mode of delivery and can help in decision making when prolonged first stage of labor is diagnosed.

Automatic measurement of head-perineum distance during intrapartum ultrasound: description of the technique and preliminary results

OBJECTIVES

To evaluate the accuracy and reliability of a new ultrasound technique for the automatic assessment of the head-perineum distance (HPD) during childbirth.

METHODS

HPD was measured on a total of 40 acquisition sessions in 30 laboring women both automatically by an innovative algorithm and manually by trained sonographers, assumed as gold standard.

RESULTS

A significant correlation was found between manual and automatic measurements (Intra-CC = 0.994). High values of the coefficient of determination (r²=0.98) and low residual errors: RMSE = 2.01 mm (4.9%) were found.

CONCLUSION

The automatic algorithm for the assessment of the HPD represents a reliable technique.