Simple two-dimensional ultrasound technique to assess intrapartum cervical dilatation: a pilot study

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.

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.

New insights on labor progression: a systematic review

The past 20 years witnessed an invigoration of research on labor progression and a change of thinking regarding normal labor. New evidence is emerging, and more advanced statistical methods are applied to labor progression analyses. Given the wide variations in the onset of active labor and the pattern of labor progression, there is an emerging consensus that the definition of abnormal labor may not be related to an idealized or average labor curve. Alternative approaches to guide labor management have been proposed; for example, using an upper limit of a distribution of labor duration to define abnormally slow labor. Nonetheless, the methods of labor assessment are still primitive and subject to error; more objective measures and more advanced instruments are needed to identify the onset of active labor, monitor labor progression, and define when labor duration is associated with maternal/child risk. Cervical dilation alone may be insufficient to define active labor, and incorporating more physical and biochemical measures may improve accuracy of diagnosing active labor onset and progression. Because the association between duration of labor and perinatal outcomes is rather complex and influenced by various underlying and iatrogenic conditions, future research must carefully explore how to integrate statistical cut-points with clinical outcomes to reach a practical definition of labor abnormalities. Finally, research regarding the complex labor process may benefit from new approaches, such as machine learning technologies and artificial intelligence to improve the predictability of successful vaginal delivery with normal perinatal outcomes.

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.

Assessment of labor progress by ultrasound vs manual examination: a randomized controlled trial

BACKGROUND

Assessment of labor progress via digital examination is considered the standard of care in most delivery rooms. However, this method can be stressful, painful, and imprecise, and multiple examinations increase the risk for chorioamnionitis. Intrapartum ultrasound was found to be an objective, noninvasive tool to monitor labor progression.

OBJECTIVE

This study aimed to investigate whether, among nulliparous women, the use of intrapartum ultrasound can reduce the rate of intrapartum fever by reducing the number of digital examinations.

STUDY DESIGN

This was a prospective, randomized controlled trial in term nulliparas admitted with prelabor rupture of membranes, induction of labor, or in latent phase of labor with a cervical dilation of <4 cm. Women were randomized into 1 of the following 2 arms: (1) labor progress assessed by ultrasound, avoiding digital examinations as much as possible; and (2) control group in which labor progression was assessed according to the regular protocol. Before the study, all labor ward physicians underwent training in intrapartum ultrasound.

RESULTS

A total of 90 women were randomized to the ultrasound group and 92 were randomized to the control group. When compared with the control group, the ultrasound group had significantly lower rates of intrapartum fever (11.1% vs 26.1%; P=.01), clinical chorioamnionitis (3.3% vs 16.5%; P>.01), and histologic chorioamnionitis (2.2% vs 9.8%; P=.03). The median number of digital examinations was significantly lower in the ultrasound group (5; interquartile range, 4-6) than in the control group (8; interquartile range, 6-10; P<.01). The median number of digital examinations per hour in the ultrasound group was significantly lower than in the control group (0.2 vs 0.4; P<.01). The induction rates, time from admission to delivery, mode of delivery, Apgar score at 5 minutes, and neonatal intensive care unit admission rates did not differ significantly between the groups.

CONCLUSION

The use of intrapartum ultrasound lessens the total number of digital examinations needed to be performed during labor and, consequently, the incidence of intrapartum fever and chorioamnionitis are reduced. No adverse effects on labor progression and short-term maternal or neonatal outcomes were noted.

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.

Agreement between digital vaginal examination and intrapartum ultrasound for labour monitoring

Sonographic approach for labour monitoring was introduced in order to improve the shortcomings of digital vaginal examination (DVE). This was a prospective study. We aimed to investigate the agreement between transperineal ultrasound (TPUS) measurements and DVE during first and second stages of labour. Patients in the first stage of labour were included. Cervical length (CL), cervical dilation (CD), cervical position (CP), foetal head descent (FHD) and foetal head rotation (FHR) were assessed by both DVE and TPUS. Agreement between two methods was examined. Eighty-five patients were included. One hundred and eighty-three paired TPUS and DVE assessments were performed. Satisfactory agreement between both methods was obtained regarding CL: systematic bias= -0.05 cm (95%CI, -0.13; 0.03), R = 0.7, p<.0001; CD: systematic bias = 0.07 cm (95%CI, -0.08 to 0.22), R = 0.93, p<.0001 and FHD: systematic bias = 0.83 cm (95%CI, 0.685-0.977), R = 0.55, p<.0001. There was a low correlation for the assessment of CP (kappa = 0.24) and FHR (kappa = 0.06). DVE was inefficient in determining FHR especially during latent phase with failure and error rates of 86% and 36%, respectively. A conceptual sonopartogram covering the hole childbirth process is presented based on reliable ultrasound measurements.Impact StatementWhat is already known on this subject? Digital vaginal examination (DVE) is used worldwide for labour monitoring. However, it is far from perfect. Some investigators have raised concerns about the value of the Bishop score because it is a subjective measure with great intra- and inter-observer variability, affected by a physician's clinical experience. Moreover, this method is intrusive, uncomfortable and may increase the risk of infection. The sonographic approach for labour monitoring was introduced in order to improve the shortcomings of DVE. Multiple studies focussed on the reliability of the sonographic method in assessing each parameter during labour. Hassan et al. were the first to determine whether it is feasible to perform assessment in the first stage of labour based only on US, and to describe a method of recording these observations: the 'sonopartogram'.What do the results of this study add? The outcomes concluded that sonographic approach was at least as accurate as the clinical examination. Moreover, a conceptual sonopartogram covering the hole childbirth process is presented based on reliable ultrasound measurements.What are the implications of these findings for clinical practice and/or further research? Clinical relevance of this sonopartogram should be evaluated in further studies.

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.

Intrapartum ultrasound and the choice between assisted vaginal and cesarean delivery

Inaccurate assessment of the fetal head position and station might increase the risk for difficult or failed assisted vaginal delivery. Compared with digital vaginal examination, an ultrasound examination is objective and more accurate. The International Society of Ultrasound in Obstetrics and Gynecology has issued practical guidelines on intrapartum ultrasound in 2018 and recommended that an ultrasound assessment should be conducted when there is suspected delay or arrest of the first or second stage of labor or before considering assisted vaginal delivery. Fetal head position is assessed transabdominally by identifying the fetal occiput, orbit, or midline cerebral echo. Studies have shown that ultrasound assessment improved the correct diagnosis of fetal head position and accuracy of instrument placement, however, it did not reduce morbidity. Studies on ultrasound assessment of asynclitism are limited but show promising results. Fetal head station is assessed transperineally in the midsagittal or axial plane. Of the various ultrasound parameters, angle of progression and head-perineum distance are the most widely studied and found to be highly correlated with the clinical fetal head station. An angle of progression of 120° correlates with a clinical head station of 0 and is an important landmark for engagement of successful vaginal delivery, whereas an angle of progression of 145° correlates with a clinical head station of ≥+2 and has been associated with successful assisted vaginal delivery. In contrast, a head perineum distance of ≥40 mm has been associated with an increased risk for difficult assisted vaginal delivery. A "head-up" direction of descent assessed transperineally in sagittal plane is also a favorable factor for successful vaginal delivery. Current evidence seems to suggest that a prediction model with >1 sonographic parameter performed better than a model that only used 1 parameter. We suggest that an algorithm model incorporating both clinical and sonographic parameters would be useful in guiding clinicians on their decision for assisted vaginal delivery.

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.

Process of fetal head descent as recorded by ultrasonography: How does this compare with the conventional first stage of labor?

OBJECTIVE

To construct an ultrasound partogram using serial transperineal sonographic measurements of the angle of fetal head progression during the first stage of labor, and to compare it with a conventional partogram based on digital vaginal examinations.

METHODS

Between 2017 and 2018, a prospective cohort study at Drum Tower Hospital, Nanjing, China, recruited 375 nulliparous women with singleton pregnancy and spontaneous onset of labor at 37 or more gestational weeks. Transperineal ultrasound scans were performed to measure the angle of progression (AoP) every 0.5-1 h until the second stage. Vaginal examinations were also used to measure cervical dilatation. Repeated-measures analysis was used to generate labor curves.

RESULTS

The labor curve generated by AoP had a pattern similar to that based on cervical dilatation. There was an initial slow period lasting approximately 5.5 h until the cervical dilatation or AoP reached the inflection point (4 cm and 119°, respectively), followed by a second, more rapid period, lasting approximately 2.5 h.

CONCLUSION

Based on ultrasound data, it was feasible to construct an "angle of progression partogram" of the first stage of labor, which was similar in pattern to the partogram based on cervical dilatation measured in the same cohort.

Sonopartogram versus conventional partogram for monitoring progress of labor: a prospective observational study

Background

Repeated digital vaginal examination during labor may be uncomfortable for women and increases the risk of ascending infection. Transperineal ultrasound can assess fetal head descent, position, and cervical dilatation without these side effects. This study was conducted to evaluate the accuracy of transperineal ultrasound in monitoring labor progress.

Results

The study included 40 primigravida women in labor. Fair correlation was found between the assessment of fetal head station by vaginal examination (VE) and fetal head perineal distance (HPD) by transperineal ultrasound (TPUS) (Kendall’s tau-b (τ) = − 0.299, 95% CI = − 0.479 to − 0.0863, p value = .0063) (Spearman rho = − .3844, p value = .0143; r2 = 0.1478). Strong correlation was found between the cervical dilatation assessed by VE and by TPUS (Pearson’s r = .8601, 95% CI = 0.7493 to 0.9240, p value < .0001, r2 = 0.7396). There is moderate agreement between VE and TPUS as regards the assessment of head position on the face-clock [weighted kappa (κ) = .557, 95% CI = .362 to.753].

Conclusion

Transperineal ultrasound can be used as an alternative to repeated digital examination for assessment of labor progress.

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.

Factors that affect ultrasound-determined labor progress in women undergoing induction of labor

BACKGROUND

The traditional approach to the assessment of labor progress is by digital vaginal examination; however, it is subjective and imprecise. Recent studies have investigated the role of transperineal ultrasonographic assessment of fetal head descent by measuring the angle of progression and head-perineum distance.

OBJECTIVE

The objective of this study was to evaluate factors that affected labor progress, which were defined by the transperineal ultrasonographic parameters, in women who achieved vaginal delivery.

STUDY DESIGN

This was a prospective longitudinal study performed in 315 women with singleton pregnancy who underwent labor induction at term between December 2016 and December 2017. Paired assessment of cervical dilation and fetal head station by vaginal examination and transperineal ultrasonographic assessment of fetal head descent (parasagittal angle of progression and head-perineum distance) were made serially after the commencement of labor induction until full cervical dilation. The researchers were blinded to the findings of the clinical team's vaginal examination and vice versa. The repeated measure data were analyzed by mixed effect models to identify the significant factors (age ≥35 years, obesity, parity, methods of labor induction, and epidural anesthesia) that affected the relationship between parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation.

RESULTS

The total number of paired vaginal examination and transperineal ultrasonographic assessments among the 261 women (82.9%) with vaginal delivery was 945, with a median of 3 per woman. The median assessment-to-assessment interval was 4.6 hours (interquartile range, 4.3-5.2). Multiparity and mechanical methods of labor induction were associated with a faster rate of fetal head descent, which was determined by head-perineum distance against fetal head station, than nulliparity and the use of a slow-release vaginal pessary, respectively. An additional increase of 0.10 cm in head-perineum distance was observed, for an unit increase in fetal head station in nulliparous women (P=.03) and women who had a slow-release vaginal pessary (P=.02), compared with multiparous women and those who had mechanical methods for labor induction. The use of epidural anesthesia was associated with a slower rate of fetal head descent, which was determined by both parasagittal angle of progression and head-perineum distance, against fetal head station. An additional decrease of 3.66 degrees in parasagittal angle of progression (P=.04) and an additional increase in 0.33 cm in head-perineum distance (P≤.001) were observed for a unit increase in fetal head station in women with the use of epidural anesthesia, compared with those without. Obese women had higher head-perineum distance overall, compared with normal weight women; at different cross-sections of time periods, obesity appeared to be associated with a slower rate of change between head-perineum distance and cervical dilation. Advanced maternal age did not affect transperineal ultrasound-determined labor progress (P>.05).

CONCLUSION

Parity, methods of labor induction, the use of epidural anesthesia, and obesity affect labor progress, which has been illustrated objectively by serial transperineal ultrasonographic assessment of fetal head descent.

Ultrasound is better tolerated than vaginal examination in and before labour

BACKGROUND

Intrapartum ultrasound has been proposed as a method of assessing labour progress but its acceptability has not been comprehensively assessed.

AIMS

We evaluated the acceptability of intrapartum ultrasound in women having vaginal examination (VE) and ultrasound (US) assessment (transabdominal (TA) and transperineal (TP)) prior to delivery, with and without regional analgesia (RA).

MATERIALS AND METHODS

Women at 24-42 weeks gestation were included in a prospective observational cohort study. The acceptability of digital VE and TP US were assessed pre- and post-examination using the modified validated Wijma Delivery Experience Questionnaire. Acceptability scores ranged 6-36 (6 being most and 36 being least positive) in six domains: positive-trust and relax, negative-harmful to baby, worrying, painful, intrusive.

RESULTS

Of 119 women recruited, 104 completed both pre- and post-assessment questionnaires. Eighty-nine per cent of women were nulliparous with median gestation 40 + 2 weeks (25-42+1 ). Thirty-two per cent had RA before assessment, 91% in total. The combined acceptability scores of both negative and positive experiences (6 = most acceptable, 36 = least acceptable) for VE and US pre-assessment were 15 and 7 respectively (P < 0.0001: Mann-Whitney U-test). VE was associated with less positive / more negative domain scoring post-assessment 12 and 6, respectively (P < 0.0001). Although RA made no difference to the perceived experience pre-VE (P = 0.9), post-VE, women with RAs considered VEs more acceptable than those without RA (P = 0.0022).

CONCLUSION(S)

This is the first study to comprehensively assess the acceptability of VE and intrapartum US. US assessment prior to delivery is more acceptable than VE. RA ameliorated the negative experience of the VE post-assessment.

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.

Is intrapartum translabial ultrasound examination painless?

OBJECTIVES

To find out whether intrapartum translabial ultrasound examination is painless by comparing pain score of ultrasound-based versus digital vaginal examination of foetal head station.

METHODS

In 94 women carrying uncomplicated-term singleton pregnancies, labour progress was assessed by translabial ultrasound, followed immediately by conventional digital vaginal examination. Pain scores (0-10) using visual analogue pain scale were obtained for both examinations. Forty-eight and forty-six sets of data were obtained in first and second stage of labour, respectively. The difference in pain scores between digital vaginal examination and translabial ultrasound was analysed.

RESULTS

The median pain score for translabial ultrasound was 0 (range 0-8), while that for vaginal examination was 4.5 (range 0-10), p < 0.05. There was no significant difference in pain scores between first and second stages of labour for translabial ultrasound (p = 0.123) and for vaginal examination (p = 0.680). The pain score for vaginal examination was higher than that of translabial ultrasound in 81.9%, similar in 13.8% and lower in 4.3% of cases. There was no statistically significant difference in pain scores obtained for digital vaginal examination by clinicians with different experience (p = 0.941).

CONCLUSIONS

Intrapartum translabial ultrasound is generally better tolerated than digital vaginal examination for assessment of labour progress, making it an acceptable adjunctive assessment tool during labour.

Prediction of delivery mode by ultrasound-assessed fetal position in nulliparous women with prolonged first stage of labor

OBJECTIVES

To ascertain if fetal head position on transabdominal ultrasound is associated with delivery by Cesarean section in nulliparous women with a prolonged first stage of labor.

METHODS

This was a prospective observational study performed at Stavanger University Hospital, Norway, and Addenbrooke's Hospital, Cambridge, UK, between January 2012 and April 2013. Nulliparous pregnant women with a singleton cephalic presentation at term and prolonged labor had fetal head position assessed by ultrasound. The main outcome was Cesarean section vs vaginal delivery, and secondary outcomes were association of fetal head position with operative vaginal delivery and duration of remaining time in labor.

RESULTS

Fetal head position was assessed successfully by ultrasound examination in 142/150 (95%) women. In total, 19/50 (38%) women with a fetus in the occiput posterior (OP) position were delivered by Cesarean section compared with 16/92 (17%) women with a fetus in a non-OP position (P = 0.01). On multivariable logistic regression analysis, the OP position predicted delivery by Cesarean section with an odds ratio (OR) of 2.9 (95% CI, 1.3-6.7; P = 0.01) and induction of labor with an OR of 2.4 (95% CI, 1.0-5.6; P = 0.05). Fetal head position was not associated with operative vaginal delivery or with remaining time in labor. The agreement between a digital and an ultrasound assessment of OP position was poor (Cohen's kappa = 0.19; P = 0.18).

CONCLUSION

OP fetal head position assessed by transabdominal ultrasound was significantly associated with delivery by Cesarean section.

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

Background

To compare 2D transperineal ultrasound assessment of cervical dilatation with vaginal examination and to investigate intra-observer variability of the ultrasound method.

Methods

A prospective observational study was performed at Skane University Hospital, Lund, Sweden between October 2013 and June 2014. Women with one fetus in cephalic presentation at term had the cervical dilatation assessed with ultrasound and digital vaginal examinations during labor. Inter-method agreement between ultrasound and digital examinations and intra-observer repeatability of ultrasound examinations were tested.

Results

Cervical dilatation was successfully assessed with ultrasound in 61/86 (71 %) women. The mean difference between cervical dilatation and ultrasound measurement was 0.9 cm (95 % CI 0.47–1.34). Interclass correlation coefficient (ICC) was 0.83 (95 % CI 0.72–0.90). Intra-observer repeatability was analysed in 26 women. The intra-observer ICC was 0.99 (95 % CI 0.97–0.99). The repeatability coefficient was ± 0.68 (95 % CI 0.45–0.91).

Conclusion

The mean ultrasound measurement of cervical dilatation was approximately 1 cm less than clinical assessment. The intra-observer repeatability of ultrasound measurements was high.

A model to predict vaginal delivery in nulliparous women based on maternal characteristics and intrapartum ultrasound

OBJECTIVE

Accurate prediction of whether a nulliparous woman will have a vaginal delivery would be a major advance in obstetrics. The objective of the study was to develop such a model based on maternal characteristics and the results of intrapartum ultrasound.

STUDY DESIGN

One hundred twenty-two nulliparous women in the first stage of labor were included in a prospective observational 2-centre study. Labor was classified as prolonged according to the respective countries' national guidelines. Fetal head position was assessed with transabdominal ultrasound and cervical dilatation by digital examination, and transperineal ultrasound was used to determine head-perineum distance and the presence of caput succedaneum. The subjects were divided into a testing set (n = 61) and a validation set (n = 61) and a risk score derived using multivariable logistic regression with vaginal birth as the outcome, which was dichotomized into no/cesarean delivery and yes/vaginal birth. Covariates included head-perineum distance, caput succedaneum, and occiput posterior position, which were dichotomized respectively into the following: ≤40 mm, >40 mm, <10 mm, ≥10 mm, and no, yes. Maternal age, gestational age, and maternal body mass index were included as continuous covariates.

RESULTS

Dichotomized score is significantly associated with vaginal delivery (P = .03). Women with a score above the median had greater than 10 times the odds of having a vaginal delivery as compared with those with a score below the median. The receiver-operating characteristic curve showed an area under the curve of 0.853 (95% confidence interval, 0.678-1.000).

CONCLUSION

A risk score based on maternal characteristics and intrapartum findings can predict vaginal delivery in nulliparous women in the first stage of labor.

Intrapartum sonography - eccentricity or necessity?

Ultrasonography has been extensively used in obstetrics and gynecology since 1980's. It found application in pediatric gynecology, procreation period, post-menopause, pregnancy monitoring and after delivery. Although the first reports on the use of ultrasonography in assessing delivery mechanism were published in 1990's, yet to date labor progress is evaluated by means of physical examination in most delivery units. Intrapartum sonography is not routinely performed despite the fact that numerous studies documented high error rates of conventional obstetrical examination. Even an experienced physician makes a mistake in every third case of the fetal head descent and fontanelle position assessment. Nowadays, obstetrician's role is not to strain for vaginal delivery at all costs, but to provide the patient in labor and her newborn with maximal safety. To achieve this objective, an obstetrician should distinguish between women who will deliver spontaneously and whose who require Cesarean section. Proper decision should be made on the basis of objective and valid evaluation of obstetric setting, which cannot be achieved solely with physical examination. Intrapartum sonography was shown to be far more accurate than digital examination. Moreover, it is not technically demanding, provides high reproducibility and neither increases the rate of ascending infection or causes discomfort to the patient. Current research suggests that if used routinely, intrapartum sonography can increase the safety of labor and reduce cesarean section rate.

Dynamic Changes in the Myometrium during the Third Stage of Labor, Evaluated Using Two-Dimensional Ultrasound, in Women with Normal and Abnormal Third Stage of Labor and in Women with Obstetric Complications

OBJECTIVE

To investigate dynamic changes in myometrial thickness during the third stage of labor.

METHODS

Myometrial thickness was measured using ultrasound at one-minute time intervals during the third stage of labor in the mid-region of the upper and lower uterine segments in 151 patients including: women with a long third stage of labor (n = 30), postpartum hemorrhage (n = 4), preterm delivery (n = 7) and clinical chorioamnionitis (n = 4). Differences between myometrial thickness of the uterine segments and as a function of time were evaluated.

RESULTS

There was a significant linear increase in the mean myometrial thickness of the upper uterine segments, as well as a significant linear decrease in the mean myometrial thickness of the lower uterine segments until the expulsion of the placenta (p < 0.001). The ratio of the measurements of the upper to the lower uterine segments increased significantly as a function of time (p < 0.0001). In women with postpartum hemorrhage, preterm delivery, and clinical chorioamnionitis, an uncoordinated pattern among the uterine segments was observed.

CONCLUSION

A well-coordinated activity between the upper and lower uterine segments is demonstrated in normal placental delivery. In some clinical conditions this pattern is not observed, increasing the time for placental delivery and the risk of postpartum hemorrhage.

Sonographic prediction of vaginal delivery in prolonged labor: a two-center study

OBJECTIVE

To investigate whether head-perineum distance (HPD) measured by transperineal ultrasound is predictive of vaginal delivery and time remaining in labor in nulliparous women with prolonged first stage of labor and to compare the predictive value with that of angle of progression (AoP).

METHODS

This was a prospective observational study at Stavanger University Hospital, Norway and Addenbrooke's Hospital, Cambridge, UK from January 2012 to April 2013, of nulliparous women with singleton pregnancies with cephalic presentation at term with prolonged first stage of labor. We used transperineal ultrasound to measure HPD (shortest distance between the outer bony limit of the fetal skull and the perineum) and AoP (angle between a line through the long axis of the symphysis and the tangent to the fetal head) and transabdominal ultrasound to classify fetal head position. The main outcomes were vaginal delivery and time remaining in labor.

RESULTS

Of 150 women enrolled, 39 underwent delivery by Cesarean section. The area under the receiver-operating characteristics curve for the prediction of vaginal delivery was 81% (95% CI, 73-89%) using HPD as the test variable and 72% (95% CI, 63-82%) using AoP. HPD was ≤ 40 mm in 84 (56%) women, of whom 77 (92%; 95% CI, 84-96%) delivered vaginally. HPD was > 40 mm in the other 66 (44%) women, of whom 34 (52%; 95% CI, 40-63%) delivered vaginally. AoP was ≥ 110° in 84 of the 145 (58%) in whom this was available and, of these, 74 (88%; 95% CI, 79-93%) delivered vaginally. AoP was < 110° in the other 61 (42%) women, of whom 35 (57%; 95% CI, 45-69%) delivered vaginally. Multivariable logistic regression analysis showed that HPD ≤ 40 mm (odds ratio (OR), 4.92; 95% CI, 1.54-15.80), AoP ≥ 110° (OR, 3.11; 95% CI, 1.01-9.56), non-occiput posterior position (OR, 3.36; 95% CI, 1.24-9.12) and spontaneous onset of labor (OR, 4.44; 95% CI, 1.42-13.89) were independent predictors for vaginal delivery. Both ultrasound methods were predictive for the time remaining in labor.

CONCLUSION

Transperineal ultrasound measurement of HPD and AoP provide important information about the likelihood of vaginal delivery and the time remaining in labor in nulliparous women with prolonged labor.

The sonopartogram: a novel method for recording progress of labor by ultrasound

OBJECTIVES

Progress of labor has hitherto been assessed by digital vaginal examination (VE). We introduce the concept of a non-intrusive ultrasound (US)-based assessment of labor progress (the 'sonopartogram') and investigate its feasibility for assessing cervical dilatation and fetal head descent and rotation.

METHODS

This was a prospective study performed in 20 women in the first stage of labor in two European maternity units. Almost simultaneous assessment of cervical dilatation and fetal head descent and rotation were made by US and digital VE.

RESULTS

The total number of paired US and digital VE assessments was 52, with a median of three per woman. Overall, 5% of sonopartogram parameters were not obtained compared with 18% of conventional digital VE parameters (P < 0.001). Assessment of cervical dilatation was possible in 86.5% of US examinations and 100% of digital VEs (P = 0.02), and dilatation was assessed as being greater by digital VE than by US (mean difference, 1.16 (95% limits of agreement, -0.76, 3.08) cm, r(2) = 0.68, P = 0.01). Fetal head descent was measured in all 52 cases by both methods (r(2) = 0.33, P < 0.001), but correlation between the two was only moderate. Head rotation was obtainable in 98% of US examinations and 46% of digital VEs (P < 0.001), with a mean difference of -3.9° (95% limits of agreement, -144.1°, 136.3°).

CONCLUSION

In this proof-of-concept study, the acquisition of data regarding progress of labor was more successful for the sonopartogram than the conventional partogram. The agreement between digital VE and US was good for cervical dilatation and head rotation but less so for head descent. US assessment of the progress of labor is feasible in most cases.