Agreement between transperineal ultrasound measurements and digital examinations of cervical dilatation during labor

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.

Implementation of sonopartogram: multicenter feasibility study

OBJECTIVES

Well-established clinical practice for assessing progress in labor involves routine abdominal palpation and vaginal examination (VE). However, VE is subjective, poorly reproducible and painful for most women. In this study, our aim was to evaluate the feasibility of systematically integrating transabdominal and transperineal ultrasound assessment of fetal position, parasagittal angle of progression (psAOP), head-perineum distance (HPD) and sonographic cervical dilatation (SCD) to monitor the progress of labor in women undergoing induction of labor (IOL). We also aimed to determine if ultrasound can reduce women's pain during such examinations.

METHODS

Women were recruited as they presented for IOL in three maternity units. Ultrasound assessments were performed in 100 women between 37 + 0 and 41 + 6 weeks' gestation. A baseline combined transabdominal and transperineal scan was performed, including assessment of fetal biometry, umbilical artery and fetal middle cerebral artery Doppler, amniotic fluid index, fetal spine and occiput positions, psAOP, HPD, SCD and cervical length. Intrapartum scans were performed instead of VE, unless there was a clinical indication to perform a VE, according to protocol. Participants were asked to indicate their level of pain by verbally giving a pain score between 0 and 10 (with 0 representing no pain) during assessment. Repeated measures data were analyzed using mixed-effect models to identify significant factors that affected the relationship between psAOP, HPD, SCD and mode of delivery.

RESULTS

A total of 100 women were included in the study. Of these, 20% delivered by Cesarean section, 65% vaginally and 15% by instrumental delivery. There were no adverse fetal or maternal outcomes. A total of 223 intrapartum ultrasound scans were performed in 87 participants (13 women delivered before intrapartum ultrasound was performed), with a median of two scans per participant (interquartile range (IQR), 1-3). Of these, 76 women underwent a total of 151 VEs with a median of one VE per participant (IQR, 0-2), with no significant difference between vaginal- or Cesarean-delivery groups. After excluding those with epidural anesthesia during examination, the median pain score for intrapartum scans was 0 (IQR, 0-1) and for VE it was 3 (IQR, 0-6). Cesarean delivery was significantly associated with a slower rate of change in psAOP, HPD and SCD.

CONCLUSIONS

Comprehensive transabdominal and transperineal ultrasound assessment can be used to assess progress in labor and can reduce the level of pain experienced during examination. Ultrasound assessment may be able to replace some transabdominal and vaginal examinations during labor. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Digital Examination vs. 4D Transperineal Ultrasound-Do They Compare in Labour Management? A Pilot Study

The aim was to compare transperineal ultrasound (TPU) with parameters of the Bishop Score during the first stage of labour and evaluate how TPU can contribute towards improving labour management. Digital examination (DE) and TPU were performed on 42 women presenting at the labour ward with regular contractions. TPU measurements included the head-symphysis distance, angle of progression, diameter of the cervical wall, cervical dilation (CD) and cervical length (CL). To examine if TPU can monitor labour progress, correlations of TPU parameters were calculated. Agreement of DE and TPU was examined for CL and CD measurements and for two groups divided into latent (CD < 5 cm) and active stages of labour (CD ≥ 5 cm). TPU parameters indicated a moderate negative correlation of CD and CL (Pearson: r = -0.667; Spearman = -0.611). The other parameters showed a weak to moderate correlation. DE and TPU measurements for CD showed better agreement during the latent stage than during the active stage. The results of the present study add to the growing evidence that TPU may contribute towards an improved labour management, suggesting a combined approach of TPU and DE to monitor the latent first stage of labour and using only DE during the active stage of labour.

Level of agreement between midwives and obstetricians performing ultrasound examination during labor

OBJECTIVE

To evaluate the level of agreement between ultrasound measurements to evaluate fetal head position and progress of labor by attending midwives and obstetricians after appropriate training.

METHODS

In this prospective study, women in the first stage of labor giving birth to a single baby in cephalic presentation at our Obstetric Unit between March 2018 and December 2019 were invited to participate; 109 women agreed. Transperineal and transabdominal ultrasound was independently performed by a trained midwife and an obstetrician. Two paired measurements were available for comparisons in 107 cases for the angle of progression (AoP), in 106 cases for the head-to-perineum distance (HPD), in 97 cases for the cervical dilatation (CD), and in 79 cases for the fetal head position.

RESULTS

We found a good correlation between the AoP measured by obstetricians and midwives (intra-class correlation coefficient [ICC] = 0.85; 95% confidence interval [CI] 0.80-0.89). There was a moderate correlation between the HPD (ICC = 0.75; 95% CI 0.68-0.82). There was a very good correlation between the CD measured (ICC = 0.94; 95% CI 0.91-0.96). There was a very good level of agreement in the classification of the fetal head position (Cohen's κ = 0.89; 95% CI 0.80-0.98).

CONCLUSIONS

Ultrasound assessment of fetal head position and progress of labor can effectively be performed by attending midwives without previous experience in ultrasound.

Use of a pocket-device point-of-care ultrasound to assess cervical dilation in labor: correlation and patient experience

OBJECTIVES

To estimate the correlation of cervical dilation between pocket-device point-of-care transperineal ultrasound (TPUS) and digital cervical examination (DCE).

METHODS

Laboring pregnant individuals ≥37 weeks of gestation presenting were prospectively evaluated for cervical dilation with a handheld pocket-sized ultrasound (Butterfly iQ+®) applied to the perineum, with a blinded DCE directly following. Subjects completed a survey to rate pain and for any preference from the examinations. To detect a moderate correlation (r=0.5) between TPUS and DCE, with an alpha of 0.05 and power of 80%, a sample size of 30 examinations were needed.

RESULTS

From April 2022 to July 2022, 30 pregnant individuals were assessed. The median cervical dilation by TPUS vs. DCE was 5.1 and 5 cm, respectively, with a Pearson's correlation coefficient, r=0.86 (95% CI 0.72 to 0.93), p<0.001. Transperineal ultrasound had a significantly less pain score than DCE, median pain score 0 vs. 2 for TPUS and DCE respectively, p<0.001. All individuals preferred the TPUS over the DCE.

CONCLUSIONS

Measurement of cervical dilation using a pocket-device point-of-care TPUS has a strong positive correlation with DCE and offers a non-invasive, convenient alternative to traditional digital exams in term, laboring patients.

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.

The active phase of labor

The active phase of labor begins at various degrees of dilatation when the rate of dilatation transitions from the relatively flat slope of the latent phase to a more rapid slope. No diagnostic manifestations demarcate its onset, other than accelerating dilatation. It ends with apparent slowing of dilatation, a deceleration phase, which is usually short in duration and frequently undetected. Several aberrant labor patterns can be detected during the active phase, including protracted dilatation, arrest of dilatation, prolonged deceleration phase and failure of descent. Underlying factors may include cephalopelvic disproportion, excessive neuraxial block, poor uterine contractility, fetal malpositions, malpresentations, uterine infection, maternal obesity, advanced maternal age and previous cesarean delivery. When an active-phase disorder is identified, cesarean delivery is justifiable if there is compelling clinical evidence of disproportion. A prolonged deceleration disorder is strongly associated with disproportion and second stage abnormalities. Shoulder dystocia may occur if vaginal delivery eventuates. This review discusses several issues raised by the introduction of new clinical practice guidelines for labor management.

The sonopartogram

The assessment of labor progress from digital vaginal examination has remained largely unchanged for at least a century, despite the current major advances in maternal and perinatal care. Although inconsistently reproducible, the findings from digital vaginal examination are customarily plotted manually on a partogram, which is composed of a graphical representation of labor, together with maternal and fetal observations. The partogram has been developed to aid recognition of failure to labor progress and guide management-specific obstetrical intervention. In the last decade, the use of ultrasound in the delivery room has increased with the advent of more powerful, portable ultrasound machines that have become more readily available for use. Although ultrasound in intrapartum practice is predominantly used for acute management, an ultrasound-based partogram, a sonopartogram, might represent an objective tool for the graphical representation of labor. Demonstrating greater accuracy for fetal head position and more objectivity in the assessment of fetal head station, it could be considered complementary to traditional clinical assessment. The development of the sonopartogram concept would require further undertaking of serial measurements. Advocates of ultrasound will concede that its use has yet to demonstrate a difference in obstetrical and neonatal morbidity in the context of the management of labor and delivery. Taking a step beyond the descriptive graphical representation of labor progress is the question of whether a specific combination of clinical and demographic parameters might be used to inform knowledge of labor outcomes. Intrapartum cesarean deliveries and deliveries assisted by forceps and vacuum are all associated with a heightened risk of maternal and perinatal adverse outcomes. Although these outcomes cannot be precisely predicted, many known risk factors exist. Malposition and high station of the fetal head, short maternal stature, and other factors, such as caput succedaneum, are all implicated in operative delivery; however, the contribution of individual parameters based on clinical and ultrasound assessments has not been quantified. Individualized risk prediction models, including maternal characteristics and ultrasound findings, are increasingly used in women's health-for example, in preeclampsia or trisomy screening. Similarly, intrapartum cesarean delivery models have been developed with good prognostic ability in specifically selected populations. For intrapartum ultrasound to be of prognostic value, robust, externally validated prediction models for labor outcome would inform delivery management and allow shared decision-making with parents.

Getting the size right: Are clinicians ready for it?

Objectives Digital examination has many uses in obstetrics and gynaecology, including cervical assessment in labour and measuring for vaginal pessaries. Clinicians must be adequately trained to perform accurate digital assessments and use this information to make decisions. We aimed to evaluate the accuracy of a clinician’s estimate for three different measuring tasks and assess whether there was any difference in the accuracy in relation to seniority or job role. Study design Doctors and midwives were recruited from two perineal trauma training events. Estimates and measurements for three different activities were recorded: length of own index finger, length of an anal sphincter model and cervical dilatation at two different dilatations (7 cm and 9 cm) using a pocket guide cervical dilatation tool. The results were analysed for accuracy of measurements according to job role and seniority. Results A total of 369 participants took part. Only 4.6% of participants accurately (to 0.1 cm) estimated the length of their index finger (0% of midwives and 5.5% of doctors). There was a significant difference (p < 0.05) when comparing average differences between estimated and actual lengths measured for doctors and midwives for almost all measurements. When comparing doctors based on seniority there was no significant difference in the accuracy of estimated lengths. A higher percentage of midwives than doctors were accurate at both 7 cm (22% vs 16.1%) and 9 cm (30.5% vs 29.5%) dilated. Conclusion We found that accuracy was poor for both doctors and midwives when asked to estimate various measurements. We suggest that training will improve awareness of finger length and therefore improve accuracy when performing digital examinations in clinical practice.

How to Reach the Best Ultrasound Performance in the Delivery Room

Ultrasonography is an instrument that is present in the maternal-fetal assessment throughout pregnancy and with widely documented benefits, but its use in intrapartum is becoming increasingly relevant. From the assessment of labor progression to the assessment of placental disorders, ultrasound can be used to correlate with physiological findings and physical examination, as its benefit in the delivery room cannot yet be proven. There are still few professionals with adequate training for its use in the delivery room and for the correct interpretation of data. Thus, this article aims to present a review of the entire applicability of ultrasound in the delivery room, considering the main stages of labor. There is still limited research in evidence-based medicine of its various possible uses in intrapartum, but it is expected that further studies can bring improvements in the quality of maternal and neonatal health during labor.

Multitask Deep Neural Network for the Fully Automatic Measurement of the Angle of Progression

The angle of progression (AoP) for assessing fetal head (FH) descent during labor is measured from the standard plane of transperineal ultrasound images as the angle between a line through the long axis of pubic symphysis (PS) and a second line from the right end of PS tangentially to the contour of the FH. This paper presents a multitask network with a shared feature encoder and three task-special decoders for standard plane recognition (Task1), image segmentation (Task2) of PS and FH, and endpoint detection (Task3) of PS. Based on the segmented FH and two endpoints of PS from standard plane images, we determined the right FH tangent point that passes through the right endpoint of PS and then computed the AoP using the above three points. In this paper, the efficient channel attention unit is introduced into the shared feature encoder for improving the robustness of layer region encoding, while an attention fusion module is used to promote cross-branch interaction between the encoder for Task2 and that for Task3, and a shape-constrained loss function is designed for enhancing the robustness to noise based on the convex shape-prior. We use Pearson's correlation coefficient and the Bland–Altman graph to assess the degree of agreement. The dataset includes 1964 images, where 919 images are nonstandard planes, and the other 1045 images are standard planes including PS and FH. We achieve a classification accuracy of 92.26%, and for the AoP calculation, an absolute mean (STD) value of the difference in AoP (∆AoP) is 3.898° (3.192°), the Pearson's correlation coefficient between manual and automated AoP was 0.964 and the Bland-Altman plot demonstrates they were statistically significant (P < 0.05). In conclusion, our approach can achieve a fully automatic measurement of AoP with good efficiency and may help labor progress in the future.

Accuracy of non-invasive methods for assessing the progress of labor in the first stage: a systematic review and meta-analysis

Background

The World Health Organization in recent years has emphasized reducing the possibility of unnecessary interventions in natural childbirth, but little is known about the accuracy of non-invasive methods when assessing the progress of labor. This paper presents a literature review to assess strategies that support non-invasive methods for labor during the first stage. It evaluates the available evidence to provide the most suitable assessments and predictions that objectively identify the progress of low-risk labor during the first stage of labor.

Methods

A search for relevant literature was conducted using the electronic databases of PubMed, CINAHL, Web of Sciences, the Cochrane Library, Scopus, Medline (OVID), and CEPS, with publications up to November 2021. Records were screened against pre-specified inclusion/exclusion criteria and the potential papers from Google Scholar were examined to identify additional papers that may have been missed. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool was used to appraise the methodological quality of the included studies. The certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Two independent investigators extracted the review’s characteristics, and discrepancies were resolved by consensus. This review calculated individual and pooled sensitivity, specificity, and positive predictive values, which were exported to STATA (version 14; Stata Corp., College Station, TX) to represent the performance of diagnostic testing.

Results

Our search returned 2283 reports of which 13 fulfilled the inclusion criteria, accounting for 2594 women. The subjects were divided into groups according to the diagnostic tests used to assess the progress of their labor, including appearance assessment and sonographic imaging parameters (head perineum distance, HPD; angle of progression, AOP, and other parameters). HPD pooled sensitivity was 0.74 (0.65–0.82), and specificity was 0.77 (0.69–0.84). The pooled diagnostic odds ratio (DOR) was 8.21 (4.67–14.41) and 10.34 (5.02–21.27), respectively. The results of subgroup analysis showed that the summary sensitivity and specificity were of medium accuracy overall. The quality of evidence as assessed with GRADE was low.

Conclusion

Vaginal examination is an intrinsic element in the use of the partogram, while transperineal ultrasound can also be used as an auxiliary tool. However, the presence of publication bias within the parameters of ultrasound indicates that the diagnostic performance may be overestimated. Thus, randomized controlled trials or large-scale prospective cohort studies are necessary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04938-y.

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.

Reliability of ultrasound versus digital vaginal examination in detecting cervical dilatation during labor: a diagnostic test accuracy systematic review

Background

This systematic review aimed to investigate the reliability of ultrasound method compared with digital vaginal examinations in detecting cervical dilation.

Methods

We searched Cochrane (CENTRAL), MEDLINE, EMBASE, CINAHL, ISI Web of Science Core Collection, Trip Database, PubMed, DARE and NHS EED, HTA, and PROSPERO. Ten observational studies with a total sample size of 856 were included in the meta-analysis.

Results

The intraclass correlation coefficient (ICC) values ranged between 0.21 and 0.69. The fixed-effect models for the ultrasound test showed an average of ICC (r = 0.32 (95% CI 0.26–0.38). Correlation between two methods was poor (r = 0.359, 95% CI 0.26–0.44). In nulliparous and multigravida participants the correlation between ultrasound measurements and digital examinations was (r = 0.349, 95% CI 0.25–0.43) and ICC (r = 0.676, 95% CI 0.419–0.833), respectively.

Conclusion

Trans-perineal ultrasonography seems to be a reliable method for assessing labor progression in multigravida women, but its usage in nulliparous women needs further studies.

Intrapartum ultrasound for assessment of cervical dilatation

Assessment of cervical dilatation by digital vaginal examination is commonly used during labor as one of the main indicators of labor progress. Despite consistent inaccuracies, this practice remains widely chosen among midwives and obstetricians. Several methods, including electromechanical and electromagnetic devices, have been trialed throughout the decades without being able to provide objective means of obtaining accurate measurements of cervical dilatation during labor. Intrapartum ultrasound in the form of transperineal or translabial applications has shown promising results in the assessment and monitoring of labor progress. Here, we described the validity of intrapartum ultrasound and its usefulness in the assessment of cervical dilatation during labor. Moreover, we highlighted the feasibility of ultrasound in obtaining these assessments.

Can ultrasound on admission in active labor predict labor duration and a spontaneous delivery?

BACKGROUND

Identifying predictive factors for a normal outcome at admission in the labor ward would be of value for planning labor care, timing interventions, and preventing labor dystocia. Clinical assessments of fetal head station and position at the start of labor have some predictive value, but the value of ultrasound methods for this purpose has not been investigated. Studies using transperineal ultrasound before labor onset show possibilities of using these methods to predict outcomes.

OBJECTIVE

This study aimed to investigate whether ultrasound measurements during the first examination in the active phase of labor were associated with the duration of labor phases and the need for operative delivery.

STUDY DESIGN

This was a secondary analysis of a prospective cohort study at Landspitali University Hospital, Reykjavík, Iceland. Nulliparous women at ≥37 weeks' gestation with a single fetus in cephalic presentation and in active spontaneous labor were eligible for the study. The recruitment period was from January 2016 to April 2018. Women were examined by a midwife on admission and included in the study if they were in active labor, which was defined as regular contractions with a fully effaced cervix, dilatation of ≥4 cm. An ultrasound examination was performed by a separate examiner within 15 minutes; both examiners were blinded to the other's results. Transabdominal and transperineal ultrasound examinations were used to assess fetal head position, cervical dilatation, and fetal head station, expressed as head-perineum distance and angle of progression. Duration of labor was estimated as the hazard ratio for spontaneous delivery using Kaplan-Meier curves and Cox regression analysis. The hazard ratios were adjusted for maternal age and body mass index. The associations between study parameters and mode of delivery were evaluated using receiver operating characteristic curves.

RESULTS

Median times to spontaneous delivery were 490 minutes for a head-perineum distance of ≤45 mm and 682 minutes for a head-perineum distance of >45 mm (log-rank test, P=.009; adjusted hazard ratio for a shorter head-perineum distance, 1.47 [95% confidence interval, 0.83-2.60]). The median durations were 506 minutes for an angle of progression of ≥93° and 732 minutes for an angle of progression of <93° (log-rank test, P=.008; adjusted hazard ratio, 2.07 [95% confidence interval, 1.15-3.72]). The median times to delivery were 506 minutes for nonocciput posterior positions and 677 minutes for occiput posterior positions (log-rank test, P=.07; adjusted hazard ratio, 1.52 [95% confidence interval, 0.96-2.38]) Median times to delivery were 429 minutes for a dilatation of ≥6 cm and 704 minutes for a dilatation of 4 to 5 cm (log-rank test, P=.002; adjusted hazard ratio, 3.11 [95% confidence interval, 1.68-5.77]). Overall, there were 75 spontaneous deliveries; among those deliveries, 16 were instrumental vaginal deliveries (1 forceps delivery and 15 ventouse deliveries), and 8 were cesarean deliveries. Head-perineum distance and angle of progression were associated with a spontaneous delivery with area under the receiver operating characteristic curves of 0.68 (95% confidence interval, 0.55-0.80) and 0.67 (95% confidence interval, 0.55-0.80), respectively. Ultrasound measurement of cervical dilatation or position at inclusion was not significantly associated with spontaneous delivery.

CONCLUSION

Ultrasound examinations showed that fetal head station and cervical dilatation were associated with the duration of labor; however, measurements of fetal head station were the variables best associated with operative deliveries.

Impact of analysis technique on our understanding of the natural history of labour: a simulation study

OBJECTIVE

To evaluate the discrepancy between historical and more recent descriptions of the first stage of labour by testing whether the statistical techniques used recently (repeated-measures polynomial and interval-censored regression) were appropriate for detection of periods of rapid acceleration of cervical dilatation as might occur at the time of transition from a latent to an active phase of labour.

DESIGN AND SETTING

A simulation study using regression techniques.

SAMPLE

We created a simulated data set for 500 000 labours with clearly defined latent and active phases using the parameters described by Friedman. Additionally, we created a data set comprising 500 000 labours with a progressively increasing rate of cervical dilatation.

METHODS

Repeated-measures polynomial regression was used to create summary labour curves based on simulated cervical examinations. Interval-censored regression was used to create centimetre-by-centimetre estimates of rates of cervical dilatation and their 95th centiles.

MAIN OUTCOME MEASURES

Labour summary curves and rates of cervical dilatation.

RESULTS

Repeated-measures polynomial regression did not detect the rapid acceleration in cervical dilatation (i.e. acceleration phase) and overestimated lengths of labour, especially at smaller cervical dilatations. There was a two-fold overestimation in the mean rate of cervical dilatation from 4 to 6 cm. Interval-censored regression overestimated median transit times, at 4- to 5-cm cervical dilatation or when cervical examinations occurred less frequently than 0.5- to 1.5-hourly.

CONCLUSION

Repeated-measures polynomial regression and interval-censored regression should not be routinely used to define labour progress because they do not accurately reflect the underlying data.

TWEETABLE ABSTRACT

Repeated-measures polynomial and interval-censored regression techniques are not appropriate to model first stage of labour.

Feasibility, Reliability, and Agreement of Transperineal Ultrasound Measurement: Results from a Longitudinal Cohort Study

OBJECTIVES

To evaluate the feasibility, reliability, and agreement of serial transperineal ultrasound (TPU) assessment of fetal head station (parasagittal angle of progression [psAOP], head-perineum distance [HPD], and head-symphysis distance [HSD]) and sonographic cervical dilatation (SCD), compared to fetal head station and cervical dilatation determined by vaginal examination, respectively.

METHODS

This was a prospective longitudinal study in singleton pregnancies undergoing induction of labor at term. Paired assessment of fetal head station and cervical dilatation by vaginal examination, with TPU assessment of psAOP, HPD, HSD, and SCD was made serially. Feasibility, correlation, reliability, and agreement were determined.

RESULTS

1,139 paired measurements among 326 women were included. psAOP and HPD were achievable in all assessments. HSD was not achievable in 3.4% (11/326) due to high fetal head station. Fetal head station by vaginal examination was positively correlated with psAOP (rho = 0.70) but negatively correlated with HPD (rho = -0.57) and HSD (rho = -0.52). The feasibility to measure SCD reduced as cervical dilatation increased. Cervical dilatation and SCD were positively correlated (rho = 0.96) with strong agreement (concordant correlation coefficient = 0.925).

CONCLUSIONS

Measurements of psAOP and HPD are feasible and correlate significantly with fetal head station by vaginal examination. Measurement of HSD is not feasible when fetal head station is high. Measurement of SCD is feasible, but it is more difficult in the advanced stage of labor. The correlation, reliability, and agreement between SCD and cervical dilatation by vaginal examination are high.

ACR Appropriateness Criteria® Assessment of Gravid Cervix

Preterm birth remains the leading cause of perinatal morbidity and mortality. Although the greatest risk factor for preterm birth is a history of prior preterm birth, a short cervical length (≤25 mm) before 24 weeks' gestational age is also associated with increased risk of spontaneous preterm delivery. As such, cervical length assessment has become of particular interest in predicting those patients at risk for preterm birth. Other clinical scenarios (eg, preterm labor, induction of labor, and active labor) may arise, in which assessment of the cervix may be of interest. Ultrasound is the mainstay imaging modality for assessing the gravid cervix, with transvaginal ultrasound recommended in patients at high risk for preterm birth or suspected preterm labor. Transperineal ultrasound is an alternate approach in those cases where transvaginal ultrasound in contraindicated. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Assessment of labor progression by intrapartum ultrasonography among term nulliparous women

OBJECTIVE

To assess cervical dilation, fetal head station, and fetal head position by intrapartum ultrasonography and to compare the approach with digital vaginal examination (DVE).

METHODS

An observational study conducted from October 2015 to January 2017 among term nulliparous women in active labor at a tertiary hospital in Delhi, India. Cervical dilation, head station, and head position were assessed by DVE, followed by ultrasonography within 10 minutes. The women's preference was also evaluated.

RESULTS

Overall, 458 observations were obtained for 215 women. Cervical dilation measured by DVE was strongly correlated with ultrasonography findings (intraclass correlation coefficient, 0.945; 95% confidence interval, 0.932-0.956; κ=0.837; P<0.001). Data for fetal head station and head position showed a fair correlation (κ=0.353 and κ=0.554, respectively; both P<0.001). The majority of women (186/215, 87%) reported a preference for ultrasonography over DVE for assessment of labor progression in a future pregnancy.

CONCLUSION

Intrapartum ultrasonography was preferred as an objective assessment tool for labor progression among term nulliparous women and therefore should be practiced in all labor rooms. Further studies on interobserver variation are recommended to establish the reproducibility of intrapartum assessment by ultrasonography.

Use of intrapartum ultrasound in term pregnant women with contractions before hospital admission

INTRODUCTION

The aim of this study was to test the hypothesis that transperineal ultrasound can be used to decide whether to admit a pregnant woman due to labor.

MATERIAL AND METHODS

In this analytical cross-sectional observational study, transperineal ultrasound was performed on pregnant women with intact membranes who came to the hospital due to contractions. A decision was made to admit women due to labor based on the ultrasound measurements. The ultrasound measurements were used to determine cervical dilation, the angle of progression, and fetal head position. The managing midwives were blinded to the results and made the final decision to admit the women based on digital vaginal examination.

RESULTS

It was possible to decide whether a woman had to be admitted for delivery or discharged due to the latent phase of labor according to the ultrasound examination in 55 of the 57 cases (96.5%). In four of the 55 cases, the decision based on ultrasound differed from the midwife's decision (7.3%). There was strong agreement between the decision to admit the pregnant women based on ultrasound measurements and the digital vaginal examination (Cohen's kappa: 0.844). It was possible to measure cervical dilation with ultrasound in 52 of the 57 cases (91.2%). The intraclass correlation coefficient for the cervical dilation measurements was 0.736 (95% confidence interval 0.539-0.848).

CONCLUSIONS

There was strong agreement between the ultrasound and digital vaginal examination results in the decision to admit singleton pregnant women at term due to labor. A large number of vaginal examinations could be avoided by using intrapartum ultrasound.

Intrapartum ultrasound assessment of cervical dilatation and its value in detecting active labor

Introduction

We aimed to examine the agreement between ultrasound and digital vaginal examination in assessing cervical dilatation in an African population and to assess the value of ultrasound in detecting active labor.

Method

A cross-sectional study was conducted in a teaching hospital in Ghana between April and September of 2016. Anterior–posterior and transverse diameters of cervical dilatation were measured with ultrasound and the mean value was compared with digital vaginal examination in 195 women in labor. Agreement between methods was examined with correlation coefficients and with Bland–Altman plots. Active labor was defined when cervix was dilated ≥ 4 cm with vaginal examinations. ROC curve analysis was conducted on the diagnostic performance of ultrasound in detecting active labor.

Results

Data were analyzed in 175 out of 195 (90%) cases where ultrasound could clearly visualize the cervix. The remaining 20 cases were all determined by digital vaginal examination as advanced cervical dilatation (≥ 8 cm), advanced head station (≥ + 2), and with ruptured membranes. The Pearson correlation coefficient (r) was 0.78 (95% CI 0.72–0.83) and the intra-class correlation coefficient was 0.76 (95% CI 0.69–0.81). Bland–Altman analysis obtained a mean difference of − 0.03 cm (95% CI − 0.18 to 0.12) with zero included in the CI intervals, indicating no significant difference between methods. Limits of agreement were from − 2.01 to 1.95 cm. Ultrasound predicted active labor with 0.87 (95% CI 0.75–0.99) as the area under the ROC curve.

Conclusion

Ultrasound measurements showed good agreement with digital vaginal examinations in assessing cervical dilatation during labor and ultrasound may be used to detect active labor.

Intrapartum ultrasound: viewpoint of midwives and parturient women and reproducibility

Introduction

Vaginal examination (VE) is known to be subjective in interpretation and is considered uncomfortable by many women. Intrapartum ultrasound aims to be more objective and less invasive. The purpose of this study was to evaluate the acceptability of introducing intrapartum ultrasound to both midwives and parturients. Furthermore, we wanted to evaluate the reproducibility of different measurements when introduced de novo among operators without prior ultrasound experience.

Subjects and methods

This study determined intra- and interobserver variability of intrapartum ultrasound in nulliparous women in labor. Ultrasound examinations were performed independently by a midwife and a gynecologist. The symphysis–head distance (SHD) and the angle of progression (AOP) were measured by translabial ultrasound. Structured questionnaires were given to midwives and parturients. Intraclass correlation coefficient (ICC) and limits of agreement (LA) were calculated to evaluate variability.

Results

A total of 33 patients were included; of whom, 28 filled in the questionnaire. A total of 19 midwives working on a delivery ward were asked to respond to the questionnaire, and 13 returned the forms. Midwives clearly continued to prefer VE over ultrasound, the majority evaluated translabial ultrasound as easy to use, but some declared to be unable to use it. The majority of patients, 71%, preferred ultrasound over VE. Reproducibility of intrapartum trans-labial ultrasound was good; ICC for interobserver variability was 0.603 (p=0.001) for SHD, and ICC for intraobserver variability was 0.844 (p<0.001) and 0.914 (p<0.001) for SHD and AOP, respectively.

Conclusion

Patients prefer ultrasound over VE; midwives tend to stick to trusted VE. Reproducibility of intrapartum ultrasound in non-experienced operators is good.

The feasibility and accuracy of ultrasound assessment in the labor room

Objective: Vaginal examination is widely used to assess the progress of labor; however, it is subjective and poorly reproducible. We aim to assess the feasibility and accuracy of transabdominal and transperineal ultrasound compared to vaginal examination in the assessment of labor and its progress. Methods: Women were recruited as they presented for assessment of labor to a tertiary inner city maternity service. Paired vaginal and ultrasound assessments were performed in 192 women at 24-42 weeks. Fetal head position was assessed by transabdominal ultrasound defined in relation to the occiput position transformed to a 12-hour clock face; fetal head station defined as head-perineum distance by transperineal ultrasound; cervical dilatation by anterior to posterior cervical rim measurement and caput succedaneum by skin-skull distance on transperineal ultrasound. Results: Fetal head position was recorded in 99.7% (298/299) of US and 51.5% (154/299) on vaginal examination (p < .0001 ¹ ). Bland-Altman analysis showed 95% limits of agreement, -5.31 to 4.84 clock hours. Head station was recorded in 96.3% (308/320) on vaginal examination (VE) and 95.9% (307/320) on US (p = .79 ¹ ). Head station and head perineum distance were negatively correlated (Spearman's r = -.57, p < .0001). 54.4% (178/327) of cervical dilatation measurements were determined using US and 100% on VE/speculum (p < .0001). Bland-Altman analysis showed 95% limits of agreement -2.51-2.16 cm. The presence of caput could be assessed in 98.4% (315/320) of US and was commented in 95.3% (305/320) of VEs, with agreement for the presence of caput of 76% (p < .05). Fetuses with caput greater than 10 mm had significantly lower head station (p < .0001). Conclusions: We describe comprehensive ultrasound assessments in the labor room that could be translated to the assessment of women in labor. Fetal head position is unreliably determined by vaginal examination and agrees poorly with US. Head perineum distance has a moderate correlation with fetal head station in relation to the ischial spines based on vaginal examination. Cervical dilatation is not reliably assessed by ultrasound except at dilatations of less than 4 cm. Caput is readily quantifiable by ultrasound and its presence is associated with lower fetal head station. Transabdominal and transperineal ultrasound is feasible in the labor room with an accuracy that is generally greater than vaginal examinations.

Comparison of effects of digital vaginal examination with transperineal ultrasound during labor on pain and anxiety levels: a randomized controlled trial

OBJECTIVE

To evaluate whether routine vaginal examination during labor is associated with increased levels of anxiety and pain compared with transperineal ultrasound assessment.

METHODS

This was a single-blinded, parallel, randomized controlled trial conducted in a tertiary care facility. Parous pregnant women without a known psychiatric condition who were seen at the care facility between November 2015 and March 2016 were included in the trial. Participants had an uneventful pregnancy and were assigned randomly to routine digital vaginal examination or transperineal ultrasound assessment during labor. Psychological distress levels, measured by the Symptom Checklist-90-Revised, and anxiety levels, measured by State-Trait Anxiety Inventory (STAI), were recorded before admission, and pain, measured using a visual analog scale, and anxiety were recorded during the latent phase of labor, the beginning of active labor and the postpartum period. A sample size of 45 women per group (n = 90) was planned to compare methods of assessment.

RESULTS

Ninety women were randomized (1:1 allocation) to one or other of the interventions. Preadmission psychological distress and anxiety levels were similar between the two groups (P = 0.93 and 0.65, respectively). Most of the studied characteristics were similar in each group including duration of labor, number of examinations, analgesic administration during labor, episiotomy rate and interval between deliveries. Visual analog scale scores revealed that pain perception was reduced during latent (mean difference, -1.5 (95% CI, -2.51 to -0.57); P < 0.01) and active (mean difference, -1.2 (95% CI, -2.45 to -0.09); P = 0.03) stages of labor and during the postpartum period (mean difference, -0.5 (95% CI, -1.02 to -0.06); P = 0.02) in participants who had a transperineal ultrasound assessment compared with participants who had a digital vaginal examination. STAI scores revealed that anxiety levels were similar between the two groups during the latent and active phases of labor and during the postpartum period (P = 0.07, P = 0.38 and P = 0.13, respectively).

CONCLUSIONS

The perception of pain was significantly reduced with the use of a transperineal ultrasound assessment compared with routine digital vaginal examination. However, only during the latent stage of labor was the magnitude of the observed effect sufficiently great to be considered clinically significant. Our results indicate that transperineal ultrasound assessment could be preferred to digital examination for the evaluation of progression of labor during this phase. Digital examination has no clinically relevant effects on state anxiety levels, as measured by the STAI. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

The effectiveness of intrapartum ultrasonography in assessing cervical dilatation, head station and position: A systematic review and meta-analysis

The objective of this review was to assess the effectiveness of intrapartum ultrasonography in measuring cervical dilatation, head station and position. Electronic literature searches were carried out of MEDLINE, CINAHL, and Web of Knowledge, plus manual reference list checks of all relevant articles. All published prospective studies comparing intrapartum ultrasonography with digital VE in the determination of cervical dilatation, head station and position were then evaluated for the success rate and level of agreement between ultrasonography and digital VE. Ultrasonography had higher success rate than digital VE in the determination of fetal head position, with a statistically significant difference in the first stage of labour. Second, although the successful determination of cervical dilatation was in favour of digital VE, the difference was not statistically significant. In addition, there was high agreement between ultrasound and digital VE findings on cervical dilatation. Lastly, a significant but moderate correlation between digital VE and ultrasound methods was found in the assessment of fetal head station. However, no meta-analysis could be done for the fetal head station due to the methodological differences between ultrasound anatomical landmarks and that of digital VE. The findings suggest that ultrasonography is superior to digital VE in the assessment of fetal head position, but has moderate correlation with digital VE in the assessment of head station. It also showed high agreement with digital VE in the assessment of cervical dilatation with no statistically significant difference in terms of success rate.