Three-dimensional ultrasound in monitoring progression of labor: a reproducibility study

Soft-tissue dystocia due to paradoxical contraction of the levator ani as a cause of prolonged second stage: concept, diagnosis, and potential treatment

Smaller pelvic floor dimensions seem to have been an evolutionary need to provide adequate support for the pelvic organs and the fetal head. Pelvic floor dimension and shape contributed to the complexity of human birth. Maternal pushing associated with pelvic floor muscle relaxation is key to vaginal birth. Using transperineal ultrasound, pelvic floor dimensions can be objectively measured in both static and dynamic conditions, such as pelvic floor muscle contraction and pushing. Several studies have evaluated the role of the pelvic floor in labor outcomes. Smaller levator hiatal dimensions seem to be associated with a longer duration of the second stage of labor and a higher risk of cesarean and operative deliveries. Furthermore, smaller levator hiatal dimensions are associated with a higher fetal head station at term of pregnancy, as assessed by transperineal ultrasound. With maternal pushing, most women can relax their pelvic floor, thus increasing their pelvic floor dimensions. Some women contract rather than relax their pelvic floor muscles under pushing, which is associated with a reduction in the anteroposterior diameter of the levator hiatus. This phenomenon is called levator ani muscle coactivation. Coactivation in nulliparous women at term of pregnancy before the onset of labor is associated with a higher fetal head station at term of pregnancy and a longer duration of the second stage of labor. In addition, levator ani muscle coactivation in nulliparous women undergoing induction of labor is associated with a longer duration of the active second stage of labor. Whether we can improve maternal pelvic floor relaxation with consequent improvement in labor outcomes remains a matter of debate. Maternal education, physiotherapy, and visual feedback are promising interventions. In particular, ultrasound visual feedback before the onset of labor can help women increase their levator hiatal dimensions and correct levator ani muscle coactivation in some cases. Ultrasound visual feedback in the second stage of labor was found to help women push more efficiently, thus obtaining a lower fetal head station at ultrasound and a shorter duration of the second stage of labor. The available evidence on the role of any intervention aimed to aid women to better relax their pelvic floor remains limited, and more studies are needed before considering its routine clinical application.

The head direction to the angle of progression ratio: a quantitative parameter for intrapartum evaluation of cephalic malposition

BACKGROUND

No previous study has evaluated the transitions of intrapartum transperineal ultrasound parameters during labor progression in cephalic malposition.

OBJECTIVE

We aimed to quantitate the characteristic trends of fetal head position and descent in cephalic malposition by analyzing the transitions of intrapartum transperineal ultrasound parameters and explore an indicator associated with the degree of cephalic malposition.

STUDY DESIGN

We retrospectively analyzed pregnant women who delivered at term from January 2018 to December 2020 at the University of Tokyo Hospital. The fetal occipital position was classified as occiput anterior and nonocciput anterior according to the fetal occipital angle of 0° to 75° and 75° to 180°, respectively. Fetal occipital angle was defined by the midline angle and position of the ocular orbit. The differences in the trends of head direction, head-symphysis distance, and progression distance relative to the angle of progression between occiput anterior and nonocciput anterior cases were evaluated. In addition, the parameters that showed differences were analyzed to evaluate their relationship to the degree of cephalic malposition.

RESULTS

A total of 502 images (occiput anterior, 319; nonocciput anterior, 183) met the inclusion criteria. The distribution of head direction values relative to the angle of progression was smaller in the nonocciput anterior group than in the occiput anterior group, whereas the head-symphysis distance and progression distance values relative to the angle of progression showed no difference in their distribution between the occiput anterior and nonocciput anterior groups. The ratio of head direction to the angle of progression was significantly smaller in the nonocciput anterior group than in the occiput anterior group (median [interquartile range], 0.03 [-0.02 to 0.10] vs 0.21 [0.12-0.28]; P<.0001). Furthermore, this ratio was negatively correlated with fetal occipital angle (Spearman correlation coefficient, -0.66).

CONCLUSION

Our results indicated that the head direction to angle of progression ratio reflects the deviation in the fetal head direction toward the maternal dorsal side, and decreases in proportion to the degree of cephalic malposition. This concept of deviation in the head direction as an indicator for evaluating cephalic malposition with intrapartum transperineal ultrasound may contribute to improving labor management in the case of cephalic malposition.

Fetal head descent assessed by transabdominal ultrasound: a prospective observational study

BACKGROUND

Determining fetal head descent, expressed as fetal head station and engagement is an essential part of monitoring progression in labor. Assessing fetal head station is based on the distal part of the fetal skull, whereas assessing engagement is based on the proximal part. Prerequisites for assisted vaginal birth are that the fetal head should be engaged and its lowermost part at or below the level of the ischial spines. The part of the fetal head above the pelvic inlet reflects the true descent of the largest diameter of the skull. In molded (reshaped) fetal heads, the leading bony part of the skull may be below the ischial spines while the largest diameter of the fetal skull still remains above the pelvic inlet. An attempt at assisted vaginal birth in such a situation would be associated with risks. Therefore, the vaginal or transperineal assessments of station should be supplemented with a transabdominal examination. We suggest a method for the assessment of fetal head descent with transabdominal ultrasound.

OBJECTIVE

To investigate the correlation between transabdominal and transperineal assessment of fetal head descent, and to study fetal head shape at different labor stages and head positions.

STUDY DESIGN

Women with term singleton cephalic pregnancies admitted to the labor ward for induction of labor or in spontaneous labor, at the Cairo University Hospital and Oslo University Hospital from December 2019 to December 2020 were included. Fetal head descent was assessed with transabdominal ultrasound as the suprapubic descent angle between a longitudinal line through the symphysis pubis and a line from the upper part of the symphysis pubis extending tangentially to the fetal skull. We compared measurements with transperineally assessed angle of progression and investigated interobserver agreement. We also measured the part of fetal head above and below the symphysis pubis at different labor stages.

RESULTS

The study population comprised 123 women, of whom 19 (15%) were examined before induction of labor, 8 (7%) in the latent phase, 52 (42%) in the active first stage and 44 (36%) in the second stage. The suprapubic descent angle and the angle of progression could be measured in all cases. The correlation between the transabdominal and transperineal measurements was -0.90 (95% confidence interval, -0.86 to -0.93). Interobserver agreement was examined in 30 women and the intraclass correlation coefficient was 0.98 (95% confidence interval, 0.95-0.99). The limits of agreement were from -9.5 to 7.8 degrees. The fetal head was more elongated in occiput posterior position than in non-occiput posterior positions in the second stage of labor.

CONCLUSION

We present a novel method of examining fetal head descent by assessing the proximal part of the fetal skull with transabdominal ultrasound. The correlation with transperineal ultrasound measurements was strong, especially early in labor. The fetal head was elongated in the occiput posterior position during the second stage of labor.

The maternal pelvic floor and labor outcome

Vaginal birth is the major cause of pelvic floor damage. The development of transperineal ultrasound has improved our understanding of the relationship between vaginal birth and pelvic floor dysfunction. The female pelvic floor dimensions and function can be assessed reliably in pregnant women. Maternal pushing associated with pelvic floor muscle relaxation is the central requirement of vaginal birth. Many studies have evaluated the role of the pelvic floor on labor outcomes. Smaller levator hiatal dimensions and incomplete or absent levator ani muscle relaxation seem to be associated with a longer duration of the second stage of labor and a higher risk of cesarean and operative deliveries. Here, we presented an overview of the current knowledge of the correlation between female pelvic floor dimension and function, as assessed by transperineal ultrasound, and labor outcome.

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.

Comparison of different methods of measuring angle of progression in prediction of labor outcome

OBJECTIVES

First, to compare the manual sagittal and parasagittal and automated parasagittal methods of measuring the angle of progression (AoP) by transperineal ultrasound during labor, and, second, to develop models for the prediction of time to delivery and need for Cesarean section (CS) for failure to progress (FTP) in a population of patients undergoing induction of labor.

METHODS

This was a prospective observational study of transperineal ultrasound in a cohort of 512 women with a singleton pregnancy undergoing induction of labor. A random selection of 50 stored images was assessed for inter- and intraobserver reliability of AoP measurements using the manual sagittal and parasagittal and automated parasagittal methods. In cases of vaginal delivery, univariate linear, multiple linear and quantile regression analyses were performed to predict time to delivery. Univariate and multivariate binomial logistic regression analyses were performed to predict CS for FTP in the first stage of labor.

RESULTS

The intraclass correlation coefficient (ICC) for the manual parasagittal method for a single observer was 0.97 (95% CI, 0.95-0.98) and for two observers it was 0.96 (95% CI, 0.93-0.98), indicating good reliability. The ICC for the sagittal method for a single observer was 0.93 (95% CI, 0.88-0.96) and for two observers it was 0.74 (95% CI, 0.58-0.84), indicating moderate reliability for a single observer and poor reliability between two observers. Bland-Altman analysis demonstrated narrower limits of agreement for the manual parasagittal approach than for the sagittal approach for both a single and two observers. The automated parasagittal method failed to capture an image in 19% of cases. The mean difference in AoP measurements between the sagittal and manual parasagittal methods was 11°. In pregnancies resulting in vaginal delivery, 54% of the variation in time to delivery was explained in a model combining parity, epidural and syntocinon use during labor and the sonographic findings of fetal head position and AoP. In the prediction of CS for FTP in the first stage of labor, a model which combined maternal factors with the sonographic measurements of AoP and estimated fetal weight was superior to one utilizing maternal factors alone (area under the receiver-operating-characteristics curve, 0.80 vs 0.76).

CONCLUSIONS

First, the method of measuring AoP with the greatest reliability is the manual parasagittal technique and future research should focus on this technique. Second, over half of the variation in time to vaginal delivery can be explained by a model that combines maternal factors, pregnancy characteristics and ultrasound findings. Third, the ability of AoP to provide clinically useful prediction of CS for FTP in the first stage of labor is limited. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Using transperineal ultrasound to predict labor onset

Background

Accurate diagnosis of labor onset is especially important for the counseling about elective induction of labor. The study aimed to evaluate whether transperineal ultrasound could better predict the timing and likelihood of spontaneous labor at term.

Methods

This single-center study was conducted between 2018 and 2019.Data on singleton pregnant women after 39 weeks and before labor onset were retrospectively reviewed.

Results

All the transperineal ultrasound parameters were well reproducible between the two doctors [intraclass correlation coefficient (ICC) for progression distance(PD) was 0.892, P<0.001], [ICC for angle of progression (AoP) was 0.881, P<0.001], [ICC for subpubic arch angle (SPA) was 0.766, P<0.001], [ICC for width of symphysis pubis (WSP) was 0.803, P<0.001]. For the pregnant women before 40 weeks, the width of symphysis pubis changed gradually with the of spontaneous labor (WSP) (r=0.33, P<0.05). For all included women, the SPA correlated with the time of spontaneous labor (SPA) (r=0.31, P<0.05).

Conclusions

The antepartum transperineal ultrasound is a simple and objective technique that better observes the initiation of labor. And with the WSP and SPA we were able to predict labor onset and help in counseling about elective induction of labor.

Reliability of transperineal ultrasound for the assessment of the angle of progression in labor using parasagittal approach versus midsagittal approach

OBJECTIVE

To assess the inter-method agreement between midsagittal (msAoP) and parasagittal (psAoP) measurements of the angle of progression (AoP) during labor. In addition, we aimed to evaluate the correlation between AoP measurements by both midsagittal and parasagittal approaches with the mode of delivery.

METHODS

We recruited a nonconsecutive series of women in active labor with a singleton uncomplicated term pregnancy with fetuses in vertex presentation. Women underwent transperineal ultrasound in the absence of uterine contractions or maternal pushing to measure both msAoP and psAoP. The inter-method agreement between the two acquisitions was then assessed. Lastly, both measurements were compared between women who had a vaginal delivery versus those who underwent cesarean section (CS).

RESULTS

Overall, 151 women were included in the study. We found an excellent agreement between msAoP and psAoP (ICC 0.935; 95% CI 0.912-0.953, p < .001). On the other hand, psAoP overestimated the measurements in comparison with msAoP (101.2 ± 15.6 versus 98.2 ± 16.0, p < .001). There was a significant correlation between both methods of AoP assessment and duration of the active second stage of labor and AoP measured by either method was significantly wider in patients who delivered vaginally compared to those who had a CS.

CONCLUSIONS

Our data showed a significant difference in the measured angle between the psAoP and the originally described msAoP. The automated measurements of AoP that have been introduced are designed using the parasagittal visualization of the more echogenic pubic arch, rather than the hypoechogenic pubic symphysis. We think that in the light of our data, care should be taken before applying data from midsagittal measurement in centers using the parasagittal automated approach.

Structured clinical examinations in labor: rekindling the craft of obstetrics

OBJECTIVES

Exact knowledge of fetal station and position is of paramount importance for reliable surveillance of labor progress and a prerequisite for safe operative vaginal procedures. Detailed clinical assessments are thoroughly described in old textbooks, but almost forgotten in contemporary obstetrics. Ultrasound is suggested as an objective diagnostic tool in active labor. Several publications have demonstrated a low correlation between ultrasound and clinical assessment of fetal head station and position, but the methods of clinical assessment in these studies are poorly described. We wanted to explore if a quality clinical assessment could perform better than clinical assessment in previous publications, by analyzing the correlation between a structured method of clinical assessment and intrapartum ultrasound.

METHODS

In all, 100 laboring women with cervical dilatation ≥7 cm were included in a prospective cohort study at Oslo University Hospital-Ullevål from October to December 2016. The study design was cross-sectional. Clinical examinations were performed by one special educated consultant (JKI), and transabdominal and transperineal ultrasound clips were recorded and examined by a blinded expert in intrapartum ultrasound (TME). Fetal position was classified as a clock face with 12 units (hourly divisions) and thereafter categorized as occiput anterior (OA), left occiput transverse (LOT), occiput posterior (OP), and right occiput transverse (ROT) positions. Fetal station was categorized clinically from -5 to +5 and measured with ultrasound as angle of progression (AoP) and head-perineum distance (HPD). AoP is the angle between a longitudinal line through the symphysis and a tangent to the head contour. HPD is the shortest distance between the fetal skull and the perineum.

RESULTS

Eight women were excluded due to strong contractions between clinical assessments and ultrasound measurements, fetal distress, or incomplete examinations. Fetal position assessed with ultrasound and clinical examination agreed exactly in 48/92 (52%) of cases, within one unit (hour) in 87/92 (95%) of cases and within two units in 90/92 (98%) of cases. It differed by three units in one case and by five units in one case. The agreement categorized into OA, LOT, OP, and ROT was good (Cohen's kappa 0.72; 95% CI 0.61-0.84). For station, the agreement was very good for both HPD (Pearson correlation coefficient r = 0.86; 95% CI 0.80-0.91) and AoP (r = 0.77; 95% CI to 0.67-0.84). The correlation between HPD and AoP was good (r = 0.76; 95% CI 0.65-0.84).

CONCLUSION

We found very good correlations between structured clinical assessments and ultrasound examinations, suggesting that an objective quality in clinical examinations is possible to achieve. More focus on clinical skills training may improve accuracy for clinicians.

Dynamic changes of fetal head descent at term before the onset of labor correlate with labor outcome and can be improved by ultrasound visual feedback

OBJECTIVE

The aim of the study was to evaluate the dynamic changes of angle of progression (AoP) before the onset of labor and their correlation with labor outcome and to investigate the effect of visual feedback using transperineal ultrasound on maternal pushing.

METHODS

We recruited a group of low-risk nulliparous women with singleton pregnancy at term. We measured AoP at rest, during pelvic floor contraction and Valsalva maneuver (before and after visual feedback). We compared AoP between women who delivered vaginally (VD) and those who underwent a cesarean section (CS). We also assessed the correlation between AoP and labor durations.

RESULTS

Overall, 222 women were included in the study; 129 (58.1%) had spontaneous VD, 35 (15.8%) had instrumental delivery, and 58 (26.1%) underwent CS. In comparison with rest, AoP decreased at PFMC (p < .001) and increased at first Valsalva (p < .001). AoP increased further significantly at Valsalva after visual feedback (p < .001). Women with VD had wider AoP at rest (p = .020), during Valsalva maneuver before (p = .024), and after visual feedback (p = .037). At cox regression analysis, wider AoP was associated with shorter first, second, and active second stages.

CONCLUSION

Wider AoP at rest and under Valsalva is associated with vaginal delivery, the shorter interval to delivery, and shorter labor duration in nulliparous women at term. The accuracy of AoP in the prediction of cesarean delivery is modest and is unlikely to be clinically applicable in isolation for the prediction of the mode of delivery.

A simple sonographic finding is associated with a successful vacuum application: the fetal occiput or forehead sign

BACKGROUND

Intrapartum ultrasound scanning has been proposed as an ancillary tool in the decision-making process of instrumental vaginal delivery.

OBJECTIVE

The purpose of this study was to evaluate the correlation between the sonographic visualization with a transperineal scan of the fetal occiput or forehead distal to the pubic symphysis with anterior or posterior presentation, respectively (fetal occiput or forehead sign), and the outcome of a vacuum delivery.

STUDY DESIGN

We conducted a retrospective cohort study of patients who underwent a vacuum application in our hospital from 2011-2017, excluding outlet applications. In each case, a preliminary transperineal scan was performed to confirm fetal presentation and position and to demonstrate the presence or absence of the fetal occiput or forehead sign. The head direction, angle of progression, and the head perineum distance were also noted. The primary outcome measure was the success of the vacuum. The secondary outcome measures included fetal complications and perineal lacerations.

RESULTS

A total of 196 consecutive patients were enrolled in the study. The occiput or forehead sign was present in 150 and was associated with a successful vaginal extraction in all cases. Of the 46 cases without the sign, 5 babies (10.8%) were delivered by cesarean section after a failed vacuum (P=.0006). The occiput or forehead sign was also associated with fewer grade 3-4 perineal lacerations (10.7% vs 35.7%; P=.0005) and cephalohematomas, although the difference was not statistically significant (1.4% vs 4.3%). There was a good correlation between the occiput or forehead sign and the other sonographic methods that previously had been proposed to predict a successful vacuum extraction, such as head direction, angle of progression, and head perineum distance.

CONCLUSION

In our hands, the fetal occiput or forehead sign was associated strongly with successful vacuum application and with a very low rate of maternal and fetal complications.

"Strategies to increase the accuracy and safety of OVD" (Clinical assessment skills and role of ultrasound, simulation training and new technologies to enhance instrument application)

Operative vaginal delivery (OVD) is commonly performed in the UK and Ireland. With skillful practice, the risks to mothers and babies are low. Caesarean section at full dilatation, particularly after failed OVD, can be more hazardous for mothers and babies. It is important to maintain and develop skills in OVD in order to provide it as a safe delivery option when the benefits outweigh the risks. As ultrasound machines have become more readily available on the labour ward, ultrasound assessment has been used to help clinicians diagnose the fetal head position and station, and also to try predict the success of the delivery. Simulation training has successfully been used in the setting of obstetric emergencies and is being developed to teach both technical and communication skills in OVD in order to improve maternal and neonatal outcomes. In this chapter we will discuss strategies to improve the accuracy and safety of OVD in more details.

ISUOG Practice Guidelines: intrapartum ultrasound

The purpose of these Guidelines is to review the published techniques of ultrasound in labor and their practical applications, to summarize the level of evidence regarding the use of ultrasound in labor and to provide guidance to practitioners on when ultrasound in labor is clinically indicated and how the sonographic findings may affect labor management. We do not imply or suggest that ultrasound in labor is a necessary standard of care.

Ultrasonographic evaluation of the second stage of labor. Predictive parameters for a successful vaginal delivery with or without neuraxial analgesia: a pilot study

PURPOSE

The aim of the study was to evaluate the progression and rotation of the fetal head during the second stage of labor using translabial ultrasound and to compare ultrasonographic data obtained in nulliparous women both receiving and not receiving neuraxial analgesia.

METHODS

The 49 patients enrolled in the study were divided into two groups according to receiving or not receiving neuraxial analgesia. Every half hour from full dilation to delivery, the ultrasonographic translabial parameters of Angle of Progression, Head Symphysis Distance, and Midline Angle were obtained and recorded by a single operator. Then, these records were compared between the two groups of patients.

RESULTS

Patients that underwent neuraxial analgesia presented with increased duration of the second stage of labor, with mean values of Angle of Progression significantly higher and of Midline Angle significantly lower for each time interval studied compared to patients without analgesia. A borderline significant relationship was found between administration of neuraxial analgesia and Head Symphysis Distance.

CONCLUSIONS

In this study, we demonstrated that combined spinal-epidural analgesia influences the duration of the second stage of labor and the initial progression and rotation of the fetal head through the birth canal, but not the kind of delivery. A correlation between Angle of Progression values and success in the application of a vacuum has been reported by other authors and confirmed in our study.

Three-dimensional/four-dimensional transperineal ultrasound: clinical utility and future prospects

During the last decade, there has been a huge advancement in the use of transperineal ultrasound (TPU) in the field of obstetrics and gynecology. Its main applications in obstetrics include the monitoring of fetal progression in labor and recently the assessment of maternal pelvic dimensions, whereas in gynecology, TPU is at present widely used for the evaluation of the female pelvic floor, opening new boundaries for the assessment of pelvic floor disorders. The association of volumetric three-dimensional techniques has largely contributed to the remarkable progress that has occurred in the use of TPU. The aim of this paper is to offer an overview of the advantages, challenges and future perspectives of the use of TPU for women’s imaging.

Prediction of time to delivery by transperineal ultrasound in second stage of labor

OBJECTIVE

To investigate whether the transperineal sonographic (TPS) parameters angle of progression (AoP) and midline angle (MLA) can predict the time remaining in the second stage of labor.

METHODS

We evaluated prospectively women with a singleton pregnancy in cephalic presentation at term between October 2013 and September 2014. TPS volumes were obtained immediately after confirmation by digital vaginal examination of a fully dilated cervix. AoP and MLA were measured offline by analyzing the ultrasound volumes. Progression of labor was evaluated every hour during the second stage. The associations of AoP and MLA with the interval between TPS assessment and delivery were evaluated using multivariable Cox proportional hazards analyses in nulliparous and parous women separately.

RESULTS

A total of 557 women were evaluated. An AoP ≥ 160° (adjusted hazard ratio (aHR), 2.52 (95% CI, 1.98-3.19)) and MLA ≤ 10° (aHR, 1.79 (95% CI, 1.35-2.34)) in nulliparous women and an AoP ≥ 150° (aHR, 1.86 (95% CI, 1.34-2.57)) and MLA ≤ 20° (aHR, 1.69 (95% CI, 1.21-2.34)) in parous women were significantly associated with the remaining time in labor. The positive/negative likelihood ratios of AoP, MLA, clinical station (fetal head descent as observed by digital examination) and clinical rotation (fetal head rotation as observed by digital examination) at these cut-off points were 3.6/0.6, 2.0/0.6, 1.6/0.6 and 1.6/0.8, respectively, in nulliparous women, and 2.4/0.6, 1.3/0.7, 7.6/0.5 and 5.2/0.7, respectively, in parous women.

CONCLUSION

TPS assessment of AoP and MLA in the second stage of labor was useful for predicting the time remaining in labor and had higher predictive value than did digital vaginal examination in nulliparous women. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of spontaneous vaginal delivery by transperineal ultrasound performed just after full cervical dilatation is determined

PURPOSE

To investigate whether transperineal ultrasound examination just after full cervical dilatation is determined can predict the mode of delivery.

METHODS

This was a prospective observational study of pregnant women. After full cervical dilatation was determined by vaginal examination during labor, transperineal ultrasound was immediately performed, and the head direction (HD), progression distance (PD), and angle of progression (AoP) were measured. The cases were divided into two groups: spontaneous vaginal delivery and operative delivery due to failure of progression. Differences between the groups were statistically analyzed using Student's t test and Fisher's exact test.

RESULTS

Of the 50 women, 42 had spontaneous vaginal deliveries and 8 had vacuum extractions. The spontaneous delivery group had significantly higher HD, PD, and AoP values than the vacuum extraction group. The areas under the receiver-operating characteristic curves for the prediction of spontaneous vaginal delivery were 0.850 for HD, 0.827 for PD, and 0.783 for AoP. The optimum cut-off points and positive predictive values were 83° and 92.9 % for HD, 56 mm and 94.9 % for PD, and 146° and 94.3 % for AoP, respectively.

CONCLUSION

Transperineal ultrasound examination just after full cervical dilatation was determined was useful in predicting spontaneous vaginal delivery.

True Reproducibility of UltraSound Techniques (TRUST): systematic review of reliability studies in obstetrics and gynecology

OBJECTIVES

To examine the quality of methods used and the accuracy of the interpretation of agreement in existing studies that examine the reliability of ultrasound measurements and judgments in obstetrics and gynecology.

METHODS

A systematic search of MEDLINE was performed on 25 March 2014, looking for studies that examined the reliability of ultrasound measurements and judgments in obstetrics and gynecology with evaluation of concordance (CCC) or intraclass (ICC) correlation coefficients or kappa as a main objective.

RESULTS

Seven hundred and thirty-three records were examined on the basis of their title and abstract, of which 141 full-text articles were examined completely for eligibility. We excluded 29 studies because they did not report CCC/ICC/kappa, leaving 112 studies that were included in our analysis. Two studies reported both ICC and kappa and were counted twice, therefore, the number used as the denominator in the analyses was 114. Only 16/114 (14.0%) studies were considered to be well designed (independent acquisition and blinded analysis) and to have interpreted the results properly. Most errors occurring in the studies are likely to overestimate the reliability of the method examined.

CONCLUSIONS

The vast majority of published studies examined had important flaws in design, interpretation and/or reporting. Such limitations are important to identify as they might create false confidence in the existing measurements and judgments, jeopardizing clinical practice and future research. Specific guidelines aimed at improving the quality of reproducibility studies that examine ultrasound methods should be encouraged.

Successful induction of labor: prediction by preinduction cervical length, angle of progression and cervical elastography

OBJECTIVE

To examine the potential value of preinduction cervical length, cervical elastography and angle of progression (AOP) in prediction of successful vaginal delivery and induction-to-delivery interval.

METHODS

This was a prospective study in 99 women with singleton pregnancy undergoing preinduction ultrasound assessment at 35-42 weeks' gestation. Cervical length, elastographic score at the internal os and AOP were determined. Regression analysis was used to assess the relationship between cervical length and both AOP and elastographic score. Logistic regression analysis was used to determine which of the maternal characteristics (cervical length, AOP, elastographic score) were significant predictors of vaginal delivery and induction-to-delivery interval.

RESULTS

Vaginal delivery occurred in 66 (66.7%) cases and Cesarean delivery was performed in 33 (33.3%) cases. There were significant correlations between cervical length and both AOP (r = - 0.319) and elastographic score (r = 0.368). Significant independent prediction of vaginal delivery and induction-to-delivery interval was provided by nulliparity and cervical length, with no additional significant contribution from electrographic score or AOP.

CONCLUSIONS

In women undergoing induction of labor, AOP and elastographic score at the internal os are unlikely to be useful in prediction of vaginal delivery and induction-to-delivery interval.

Sonographic pattern of fetal head descent: relationship with duration of active second stage of labor and occiput position at delivery

OBJECTIVES

The objectives of this study were firstly to assess the longitudinal changes of various sonographic parameters of fetal head progression in relation to length of active second stage of labor, and secondly to compare ultrasound findings obtained longitudinally among fetuses with persistent occiput posterior (OP) vs those with persistent occiput anterior (OA) position.

METHODS

From a series of nulliparous low-risk women at term attending the labor ward of our university hospital, transperineal ultrasound volumes were prospectively acquired at the beginning of the active second stage (T1) and at 40-min intervals thereafter until delivery (T2, T3). Sonographic parameters were derived from offline analysis of each volume, including the angle of progression (AoP), progression distance (PD), head-symphysis distance (HSD), head direction (HD) and midline angle. These parameters were compared between patients who delivered within 60 min from the beginning of the active second stage of labor (early delivery) and those who remained undelivered by that time (late delivery). Fetal head position was determined from stored digital images of transabdominal examinations performed at the beginning of the active second stage. Comparison was performed between fetuses with OA and those with persistent OP position at delivery.

RESULTS

Spontaneous vaginal delivery was achieved in 58 (81.7%) cases, whereas vacuum extraction and Cesarean section were performed in eight (11.3%) and five (7.0%) cases, respectively. Delivery was achieved within 60 min from the beginning of the active second stage in 44 (62.0%) patients. In the early vs late delivery groups, measurements of AoP, HSD and PD at T1 were significantly different (AoP, 143.9 ± 20.5° vs 125.3 ± 15.0°, P < 0.001; HSD, 14.8 ± 4.5 mm vs 20.9 ± 5.8 mm, P < 0.001; PD, 44.0 ± 14.1 vs 35.0 ± 13.1 mm, P = 0.008). On logistic regression analysis of data obtained at T1, maternal body mass index, oxytocin administration, neonatal birth weight and HSD appeared to predict independently duration of the active second stage. Among fetuses delivering in the OP position (n = 10, 13.5%), Cesarean delivery was significantly more common than in those delivering in the OA position (n = 5 (50.0%) vs n = 2 (3.1%), P = 0.001). Women with persistent OP position compared with OA showed a significantly different AoP at T1 (122 ± 17° vs 138 ± 20°, P = 0.016), HD and HSD at T1 (HD, 112 ± 17 mm vs 86 ± 19 mm, P < 0.001; HSD, 16.5 ± 5.4 mm vs 22.8 ± 6.6 mm, P = 0.008) and at T2 (HD, 120 ± 16 vs 82 ± 27 mm, P = 0.008; HSD, 12.6 ± 3.4 mm vs 18.5 ± 5.4 mm, P = 0.038).

CONCLUSIONS

AoP, PD and HSD are significantly different between patients undergoing delivery before or after 60 min from the beginning of the active second stage of labor. Ultrasound parameters are among the significant predictors of duration of the active second stage. Moreover, in fetuses persisting in the OP position vs those delivering in the OA position, fetal head progression seems to differ at early phases of the active second stage.

Agreement between two- and three-dimensional transperineal ultrasound methods for assessment of fetal head-symphysis distance in active labor

OBJECTIVES

To assess the intermethod agreement between two-dimensional (2D) and three-dimensional (3D) transperineal ultrasound methods in measuring a new index of fetal head station (the fetal head-symphysis distance (HSD)) in active labor, and to assess potential factors that may affect their agreement.

METHODS

HSD was measured by transperineal ultrasound in 86 women in active labor, once using a 2D and once using a 3D technique. 2D images were acquired first in 43 cases and 3D images were acquired first in the other 43 women. Intermethod agreement between 2D and 3D methods was analyzed by means of intraclass correlation coefficient (ICC) and Bland-Altman analysis. In addition, potential factors affecting the intermethod reproducibility were investigated including fetal occiput position, order of acquisition, fetal head station, stage of labor, maternal body mass index and use of epidural analgesia, using the ANOVA test to check for systematic bias and Levene's test for homoscedasticity.

RESULTS

Good agreement was demonstrated between 2D and 3D measurements of HSD (ICC, 0.949 (95% CI, 0.914-0.984)). No evidence of systematic difference was shown between the two methods (average difference ± SD = 0.03 ± 2.29 mm; P = 0.888). The only factor that had a significant effect on systematic difference between 2D and 3D methods was order of acquisition (P = 0.042); the first observation was higher regardless of the method used. Fetal head station had a significant effect on the homogeneity between the two methods (P = 0.004) with a better 2D-3D agreement obtained at lower head stations (SD of differences: 1.63 vs 2.59 mm).

CONCLUSIONS

There is very good agreement between 2D and 3D methods of assessing HSD. Agreement is better in lower fetal head stations.

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.

Intrapartum transperineal ultrasound assessment of fetal head progression in active second stage of labor and mode of delivery

OBJECTIVE

To compare longitudinal changes in angle of progression (AoP) and midline angle (MLA) during the active second stage of labor according to the mode of delivery.

METHODS

A three-dimensional transperineal ultrasound volume was acquired in a series of nulliparous women at the beginning of the active second stage (T1) and every 20 min thereafter (T2, T3, T4, T5 and T6). Following delivery, all ultrasound volumes were analyzed and AoP and MLA were measured.

RESULTS

Among 71 women included in the study, 58 underwent spontaneous vaginal delivery (group A) and 13 underwent operative delivery (group B) (eight by vacuum extraction and five by Cesarean section). When compared with Group B, Group A had a wider AoP only at T1 (140.0 ± 20.2° vs. 122.9 ± 16.7°; P = 0.010) and T2 (149.7 ± 20.7° vs. 126.9 ± 17.5°; P = 0.006). MLA was narrower in group A only at T3 (21.2 ± 11.7° vs. 40.8 ± 27.9°; P = 0.043), T4 (18.2 ± 15.0° vs. 47.4 ± 29.6°; P = 0.020) and T5 (18.3 ± 6.0° vs. 34.7 ± 4.2°; P = 0.034). On stepwise forward multiple logistic regression analysis, both AoP and MLA were independently associated with operative delivery (OR = 0.955 and OR = 1.018, respectively).

CONCLUSION

Ultrasonographic assessment of fetal head descent in the second stage of labor may play a role in the prediction of the mode of delivery.

Fetal head-symphysis distance: a simple and reliable ultrasound index of fetal head station in labor

OBJECTIVES

To assess the reproducibility of measurement of a new sonographic index of fetal head station in labor, the fetal head-symphysis distance (HSD), using three-dimensional ultrasound, and its correlation with digital assessment of fetal head descent and with the angle of progression (AoP).

METHODS

Three-dimensional (3D) ultrasound volumes were acquired from 47 nulliparous women in active labor following assessment of fetal head station with digital examination. The HSD (the distance between the lower edge of the pubic symphysis and the nearest point of the fetal skull) was measured independently by two operators in order to evaluate intra- and interobserver reproducibility. The correlation between HSD, AoP and fetal head station was evaluated using regression analysis. Using 3D tomographic ultrasound imaging (TUI), measurements of the HSD were obtained in different parasagittal planes to evaluate the influence of inaccurate alignment of the probe with the midline of the pelvis.

RESULTS

Measurement of HSD showed high intraobserver (intraclass correlation coefficient (ICC) = 0.995; 95% CI, 0.991-0.997) and interobserver (ICC = 0.991; 95% CI, 0.984-0.995) reliability. In addition, a high correlation was demonstrated between mid-sagittal and parasagittal HSD measurements. HSD showed significant negative correlation with both fetal head station and AoP.

CONCLUSION

Fetal HSD is a simple and reliable method for the assessment of fetal head descent in labor.

Agreement between two- and three-dimensional transperineal ultrasound methods in assessing fetal head descent in the first stage of labor

OBJECTIVE

To study intraobserver repeatability and intermethod agreement between two- (2D) and three-dimensional (3D) transperineal ultrasound methods in assessing fetal head descent during the first stage of labor.

METHODS

Fetal head descent was measured with transperineal ultrasound as the fetal head-perineum distance and the angle of progression in 106 primiparous women with prolonged first stage of labor. A single obstetrician performed all the scans, and another obstetrician analyzed the acquired 2D images and 3D volumes, blinded to clinical assessments and labor outcome. Intraobserver repeatability and intermethod agreement between 2D and 3D methods were analyzed.

RESULTS

The repeatability coefficient was ± 4.1 mm in 2D acquisitions and ± 1.7 mm in 3D acquisitions of fetal head-perineum distance. The intraclass correlation coefficients (ICC) were 0.94 for 2D and 0.99 for 3D measurements. The angle of progression repeatability coefficients were ± 6.7° using 2D and ± 5.7° using 3D ultrasound and ICCs were 0.91 and 0.94, respectively. The intermethod ICC for fetal head-perineum distance in 2D vs 3D acquisitions was 0.95 and for angle of progression it was 0.93; the intermethod 95% limits of agreement were - 5.8 mm to + 7.2 mm and - 8.9° to + 13.7°, respectively. Cohen's kappa for 2D vs 3D acquisitions was 0.85 using 40 mm as a cut-off level for fetal head-perineum distance and 0.79 using 110° as cut-off level for angle of progression.

CONCLUSIONS

For one ultrasound operator the intraobserver repeatability and agreement between 2D and 3D ultrasound methods in prolonged first stage of labor were good. Given that 2D methods are simpler to learn and can be analyzed quickly online, 2D equipment might therefore be preferred in the labor room.

Intrapartum sonographic imaging of fetal head asynclitism

Anterior asynclitism was suspected on digital examination of a laboring woman with late arrest of dilatation and no evidence of fetal head progression. Clinical examination revealed a fixed non-engaged fetal head (station −1), with a transverse posterior sagittal suture. A static three-dimensional volume was obtained by translabial ultrasound, offline analysis of which confirmed the clinical diagnosis of anterior asynclitism. Owing to the posterior twisting of the head towards the sacrum, the midline echo could only be obtained by cutting the volume with an oblique line, the direction of which was not perpendicular to the pubis as expected in cases of synclitic head. The sonographic appearance of the midline echo approaching the sacrum in a non-engaged transverse fetal head strongly supports the clinical suspicion of anterior asynclitism.

Urethral ultrasound as a screening tool for stricture recurrence after oral mucosa graft urethroplasty

OBJECTIVE

To evaluate the efficacy of sonourethrography (SUG) in combination with voiding pattern analysis to determine success after oral mucosa graft (OMG) urethroplasty. OMG urethroplasty is a standard treatment for men with recurrent urethral stricture. Because of its performance, the optimum follow-up algorithm remains controversial.

MATERIAL AND METHODS

Forty-nine patients (mean age 51 years) who underwent OMG urethroplasty were retrospectively identified. All men were subjected to a validated voiding questionnaire (International Prostate Symptom Score [IPSS]), SUG, uroflowmetry, and residual urine measurement. The predictive value was analyzed with regard to stricture recurrence or patency as well as to urethral diameter. Retrograde urethrography was done to confirm the diagnosis.

RESULTS

Strictures were bulbar in 39, penile in 4, and combined in 6 patients. Mean stricture length was 3.8 cm (range 1-10). Mean follow-up after surgery was 35 (range 15-70) months. SUG showed a mean diameter of 7.6 mm for bulbar grafts and 4.6 mm for penile grafts. Stricture recurrence was seen in 4 (8%) patients, yielding a significantly lower urethral width of 2.3 mm (P<.005). Retrograde urethrography confirmed the patency status in all. The average maximum flow rate after successful repair was 36.6 mL/s, whereas those with recurrent strictures showed rates of 11.2 (P<.03). Similar results were achieved for residual urine (P<.05). IPSS values increased from 5.1 to 12.5 in patients with recurrence (P<.01).

CONCLUSION

An algorithm consisting of SUG, uroflowmetry, residual urine and IPSS assessment reliably identifies stricture recurrence. Routine retrograde urethrography may therefore be unnecessary in the follow-up of OMG urethroplasty.

Prediction of delivery mode with transperineal ultrasound in women with prolonged first stage of labor

OBJECTIVE

To investigate if fetal head-perineum distance and angle of progression measured with two-dimensional (2D) and three-dimensional (3D) transperineal ultrasound could predict outcome of labor in primiparous women with prolonged first stage of labor.

METHODS

This was a prospective observational study of 110 primiparous women with singleton cephalic presentation at term diagnosed with prolonged first stage of labor. Digital assessment of fetal station was related to the ischial spine. Fetal head descent was measured with transperineal ultrasound as the shortest distance from the fetal head to the perineum, and the angle between the pubic symphysis and the fetal head. Receiver-operating characteristics (ROC) curves were constructed and 2D and 3D data acquisitions were compared. The stored 3D volumes were assessed by an examiner blinded to all other data. Vaginal delivery vs. Cesarean section was the primary outcome.

RESULTS

Cesarean section was performed in 25% of the women. Areas under the ROC curves for prediction of vaginal delivery were 81% (95% confidence interval (CI), 71-91%) (P < 0.01) and 76% (95% CI, 66-87%) (P < 0.01) for fetal head-perineum distance and angle of progression, respectively, as measured by 2D ultrasound and 66% (95% CI, 54-79%) for digital assessment of fetal station (P = 0.01). In 50% of women fetal head-perineum distance was ≤ 40 mm and 93% (95% CI, 83-97%) of them delivered vaginally vs. 18% (95% CI, 5-48%) with distance > 50 mm. In 48% of women the angle of progression was ≥ 110° and 87% (95% CI, 75-93%) of them delivered vaginally vs. 38% (95% CI, 21-57%) with angle < 100°. Results from 2D and 3D acquisitions were similar.

CONCLUSION

Fetal head-perineum distance and angle of progression measured with 2D or 3D ultrasound can predict labor outcome, with similar predictive values for the two techniques.