A national survey on current practice of ultrasound in labor ward

OBJECTIVES

Use of ultrasonography has been suggested as an accurate adjunct to clinical evaluation of fetal position and station during labor. There are no available reports concerning its actual use in delivery wards. The aim of this survey was to evaluate the current practice regarding the use of ultrasonography during labor.

METHODS

A questionnaire was sent to members of the Italian Society of Ultrasound in Obstetrics and Gynecology employed in delivery wards. The qFeuestionnaire was made up of 22 questions evaluating participant characteristics and the current use of ultrasound in labor in their hospital of employment. The answers were grouped according to participant characteristics.

RESULTS

A total of 200 participants replied. Ultrasound was considered useful before an operative vaginal delivery by 59.6 % of respondents, while 51.8 and 52.5 % considered it useful in the management of prolonged first and second stages of labor, respectively. The major indication for ultrasound use during labor was the assessment of fetal occiput position. The major difficulties in its application were the perceived lack of training and the complexity of the ultrasound equipment use. Participants that reported fewer difficulties were those employed in hospitals with a higher number of deliveries or having delivery units with more years of experience using ultrasound in labor, or those who had attended specific training courses.

CONCLUSIONS

The results indicate that, despite the reported evidence of a higher accuracy of ultrasound compared to clinical evaluation in assessing fetal position and station, its use is still limited, even amongst maternal-fetal medicine practitioners specialized in ultrasonography.

Ultrasonographic Evaluation of the Second Stage of Labor according to the Mode of Delivery: A Prospective Study in Greece

BACKGROUND AND OBJECTIVES

Accurate diagnosis of labor progress is crucial for making well-informed decisions regarding timely and appropriate interventions to optimize outcomes for both the mother and the fetus. The aim of this study was to assess the progress of the second stage of labor using intrapartum ultrasound.

MATERIAL AND METHODS

This was a prospective study (December 2022-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Maternal-fetal and labor characteristics were recorded, and two ultrasound parameters were measured: the angle of progression (AoP) and the head-perineum distance (HPD). The correlation between the two ultrasonographic values and the maternal-fetal characteristics was investigated. Multinomial regression analysis was also conducted to investigate any potential predictors of the mode of delivery.

RESULTS

A total of 82 women at the second stage of labor were clinically and sonographically assessed. The mean duration of the second stage of labor differed between vaginal and cesarean deliveries (65.3 vs. 160 min; p-value < 0.001) and between cesarean and operative vaginal deliveries (160 vs. 88.6 min; p-value = 0.015). The occiput anterior position was associated with an increased likelihood of vaginal delivery (OR: 24.167; 95% CI: 3.8-152.5; p-value < 0.001). No significant differences were identified in the AoP among the three different modes of delivery (vaginal: 145.7° vs. operative vaginal: 139.9° vs. cesarean: 132.1°; p-value = 0.289). The mean HPD differed significantly between vaginal and cesarean deliveries (28.6 vs. 41.4 mm; p-value < 0.001) and between cesarean and operative vaginal deliveries (41.4 vs. 26.9 mm; p-value = 0.002); it was correlated significantly with maternal BMI (r = 0.268; p-value = 0.024) and the duration of the second stage of labor (r = 0.256; p-value = 0.031). Low parity (OR: 12.024; 95% CI: 6.320-22.876; p-value < 0.001) and high HPD (OR: 1.23; 95% CI: 1.05-1.43; p-value = 0.007) were found to be significant predictors of cesarean delivery.

CONCLUSIONS

The use of intrapartum ultrasound as an adjunctive technique to the standard clinical evaluation may enhance the diagnostic approach to an abnormal labor progress and predict the need for operative vaginal or cesarean delivery.

Ultrasound in labor: clinical practice guideline and recommendation by the WAPM-World Association of Perinatal Medicine and the PMF-Perinatal Medicine Foundation

This recommendation document follows the mission of the World Association of Perinatal Medicine in collaboration with the Perinatal Medicine Foundation. We aim to bring together groups and individuals throughout the world for standardization to implement the ultrasound evaluation in labor ward and improve the clinical management of labor. Ultrasound in labor can be performed using a transabdominal or a transperineal approach depending upon which parameters are being assessed. During transabdominal imaging, fetal anatomy, presentation, liquor volume, and placental localization can be determined. The transperineal images depict images of the fetal head in which calculations to determine a proposed fetal head station can be made.

Sonographic knowledge of occiput position to decrease failed operative vaginal delivery: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study aimed to assess the efficacy of sonographic assessment of fetal occiput position before operative vaginal delivery to decrease the number of failed operative vaginal deliveries.

DATA SOURCES

The search was conducted in MEDLINE, Embase, Web of Science, Scopus, ClinicalTrial.gov, Ovid, and Cochrane Library as electronic databases from the inception of each database to April 2021. No restrictions for language or geographic location were applied.

STUDY ELIGIBILITY CRITERIA

Selection criteria included randomized controlled trails of pregnant women randomized to either sonographic or clinical digital diagnosis of fetal occiput position during the second stage of labor before operative vaginal delivery.

METHODS

The primary outcome was failed operative vaginal delivery, defined as a failed fetal operative vaginal delivery (vacuum or forceps) extraction requiring a cesarean delivery or forceps after failed vacuum. The summary measures were reported as relative risks or as mean differences with 95% confidence intervals using the random effects model of DerSimonian and Laird. An I² (Higgins I²) >0% was used to identify heterogeneity.

RESULTS

A total of 4 randomized controlled trials including 1007 women with singleton, term, cephalic fetuses randomized to either the sonographic (n=484) or clinical digital (n=523) diagnosis of occiput position during the second stage of labor before operative vaginal delivery were included. Before operative vaginal delivery, fetal occiput position was diagnosed as anterior in 63.5% of the sonographic diagnosis group vs 69.5% in the clinical digital diagnosis group (P=.04). There was no significant difference in the rate of failed operative vaginal deliveries between the sonographic and clinical diagnosis of occiput position groups (9.9% vs 8.2%; relative risk, 1.14; 95% confidence interval, 0.77-1.68). Women randomized to sonographic diagnosis of occiput position had a significantly lower rate of occiput position discordance between the evaluation before operative vaginal delivery and the at birth evaluation when compared with those randomized to the clinical diagnosis group (2.3% vs 17.7%; relative risk, 0.16; 95% confidence interval, 0.04-0.74; P=.02). There were no significant differences in any of the other secondary obstetrical and perinatal outcomes assessed.

CONCLUSION

Sonographic knowledge of occiput position before operative vaginal delivery does not seem to have an effect on the incidence of failed operative vaginal deliveries despite better sonographic accuracy in the occiput position diagnosis when compared with clinical assessment. Future studies should evaluate how a more accurate sonographic diagnosis of occiput position or other parameters can lead to a safer and more effective operative vaginal delivery technique.

Intrapartum sonographic assessment of the fetal head flexion in protracted active phase of labor and association with labor outcome: a multicenter, prospective study

BACKGROUND

To date, no research has focused on the sonographic quantification of the degree of flexion of the fetal head in relation to the labor outcome in women with protracted active phase of labor.

OBJECTIVE

This study aimed to assess the relationship between the transabdominal sonographic indices of fetal head flexion and the mode of delivery in women with protracted active phase of labor.

STUDY DESIGN

Prospective evaluation of women with protracted active phase of labor recruited across 3 tertiary maternity units. Eligible cases were submitted to transabdominal ultrasound for the evaluation of the fetal head position and flexion, which was measured by means of the occiput-spine angle in fetuses in nonocciput posterior position and by means of the chin-to-chest angle in fetuses in occiput posterior position. The occiput-spine angle and the chin-to-chest angle were compared between women who had vaginal delivery and those who had cesarean delivery. Cases where obstetrical intervention was performed solely based on suspected fetal distress were excluded.

RESULTS

A total of 129 women were included, of whom 43 (33.3%) had occiput posterior position. Spontaneous vaginal delivery, instrumental delivery, and cesarean delivery were recorded in 66 (51.2%), 17 (13.1%), and 46 (35.7%) cases, respectively. A wider occiput-spine angle was measured in women who had vaginal delivery compared with those submitted to cesarean delivery owing to labor dystocia (126±14 vs 115±24; P<.01). At the receiver operating characteristic curve, the area under the curve was 0.675 (95% confidence interval, 0.538-0.812; P<.01), and the optimal occiput-spine angle cutoff value discriminating between cases of vaginal delivery and those delivered by cesarean delivery was 109°. A narrower chin-to-chest angle was measured in cases who had vaginal delivery compared with those undergoing cesarean delivery (27±33 vs 56±28 degrees; P<.01). The area under the curve of the chin-to-chest angle in relation to the mode of delivery was 0.758 (95% confidence interval, 0.612-0.904; P<.01), and the optimal cutoff value discriminating between vaginal delivery and cesarean delivery was 33.0°.

CONCLUSION

In women with protracted active phase of labor, the sonographic demonstration of fetal head deflexion in occiput posterior and in nonocciput posterior fetuses is associated with an increased incidence of cesarean delivery owing to labor dystocia. Such findings suggest that intrapartum ultrasound may contribute in the categorization of the etiology of labor dystocia.

Predicting cesarean delivery for failure to progress as an outcome of labor induction in term singleton pregnancy

BACKGROUND

Induction of labor is one of the most common interventions in modern obstetrics, and its frequency is expected to continue to increase. There is inconsistency as to how failed induction of labor is defined; however, the majority of studies define success as the achievement of vaginal delivery. Induction of labor in nulliparous women poses an additional challenge with a 15% to 20% incidence of failure, ending in emergency operative deliveries. The Bishop score has been traditionally used before decisions for induction of labor. Nonetheless, it is subjective and prone to marked interobserver variation. Several studies have been conducted to find alternative predictors, yet a reliable, objective method still remains to be introduced and validated. Hence, there is still a need for the development of new predictive tools to facilitate informed decision making, optimization of resources, and minimization of potential risks of failure. Furthermore, a peripartum transperineal ultrasound scan has been proven to provide objective, noninvasive assessment of labor.

OBJECTIVE

This study aimed to assess the feasibility of developing and validating an objective and reproducible model for the prediction of cesarean delivery for failure to progress as an outcome of labor induction in term singleton pregnancies.

STUDY DESIGN

This was a prospective observational cohort study conducted in Cairo University Hospitals and University of Bologna Hospitals between November 2018 and November 2019. We recruited 382 primigravidae with singleton term pregnancies in cephalic presentation. All patients had baseline Bishop scoring together with various transabdominal and transperineal ultrasound assessments of the fetus, maternal cervix, and pelvic floor. The managing obstetricians were blinded to the ultrasound scan findings. The method and indication of induction of labor, the total duration of stages of labor, mode of birth, and neonatal outcomes were all recorded. Women who had operative delivery for fetal distress or indications other than failure to progress in labor were excluded from the final analysis, leaving a total of 344 participants who were randomly divided into 243 and 101 pregnancies that constituted the model development and cross-validation groups, respectively.

RESULTS

It was possible to perform transabdominal and transperineal scans and assess all the required parameters on all study participants. Univariate and multivariate analyses were used for selection of potential predictors and model fitting. The independent predictive variables for cesarean delivery included maternal age (odds ratio, 1.12; P=.003), cervical length (odds ratio, 1.08; P=.04), angle of progression at rest (odds ratio, 0.9; P=.001), and occiput posterior position (odds ratio, 5.7; P=.006). We tested the performance of the prediction model on our cross-validation group. The calculated areas under the curve for the ability of the model to predict cesarean delivery were 0.7969 (95% confidence interval, 0.71-0.87) and 0.88 (95% confidence interval, 0.79-0.97) for the developed and validated models, respectively.

CONCLUSION

Maternal age and sonographic fetal occiput position, angle of progression at rest, and cervical length before labor induction are very good predictors of induction outcome in nulliparous women at term.

Sonographic diagnosis of fetal head deflexion and the risk of cesarean delivery

BACKGROUND

Malpositions and deflexed cephalic malpresentations are well recognized causes of dysfunctional labor, may result in fetal and maternal complications, and are diagnosed more precisely with an ultrasound examination than with a digital examination.

OBJECTIVE

This study aimed to assess the incidence of malpositions and deflexed cephalic malpresentations at the beginning of the second stage of labor and to evaluate the role of the sonographic diagnosis of deflexion in the prediction of the mode of delivery.

STUDY DESIGN

Women in labor with a singleton pregnancy at term with fetuses in a cephalic presentation at 10 cm of cervical dilatation were prospectively examined. A transabdominal ultrasound was performed to assess the fetal head position by demonstrating the fetal occiput or the eyes. Deflexion was assessed by the measurement of the occiput-spine angle when the occiput was anterior or transverse and by qualitative assessment of the relationship between chin and thorax when the occiput was posterior. Transperineal ultrasound was performed in occiput posterior fetuses to discriminate between sinciput, brow, and face presentation. Maternal, labor, and neonatal parameters including maternal age, induction of labor, use of epidural, birthweight, arterial pH, and neonatal intensive care unit admission were recorded. Patients were divided into 2 groups according to the sonographic diagnosis of head deflexion. Adjusted odds ratios were calculated using multivariate logistic regression to determine the association between cesarean delivery and the 2 groups. In addition, labor and neonatal characteristics were compared between occiput anterior and occiput posterior-occiput transverse fetuses.

RESULTS

Of the 200 women at the beginning of the second stage, the fetus was in occiput anterior position in 156 (78%), transverse in 11 (5.5%), and posterior in 33 (16.5%) cases. Deflexion was diagnosed in 33 of 156 (21.2%) occiput anterior fetuses and 19 of 44 (43.2%) occiput posterior and occiput transverse fetuses. Cesarean deliveries were significantly associated with fetal head deflexion both in occiput anterior (P=.001) and occiput posterior (P<.001) fetuses. Sonographic diagnosis of fetal head deflexion was an independent risk factor for cesarean delivery both in occiput anterior (adjusted odds ratio, 5.37; 95% confidence interval, 1.819-15.869) and occiput posterior (adjusted odds ratio, 13.9; 95% confidence interval, 1.958-98.671) cases, and it was an independent risk factor for cesarean delivery regardless of the occiput position (adjusted odds ratio, 5.83; 95% confidence interval, 2.47-13.73).

CONCLUSION

The sonographic diagnosis of fetal head deflexion at the beginning of the second stage increases the risk of cesarean delivery.

Ultrasound feedback training increases trainee accuracy in vaginal assessment of fetal head position in labor

OBJECTIVE

To evaluate the impact of an immediate ultrasound feedback intervention on trainee accuracy in vaginal-examination-based assessment of fetal head position.

METHODS

This was a prospective cohort study conducted at a single tertiary care center. Six third-year and six fourth-year residents in an obstetrics and gynecology residency training program were the study subjects. The third-year residents underwent a training intervention in which they assessed fetal head position by transvaginal digital examination and then received immediate feedback through ultrasound demonstration of the actual position. All examinations were performed in women with a singleton gestation ≥ 35 weeks and cervical dilation ≥ 8 cm, following rupture of membranes. The comparison groups were third-year residents before, during and after training and fourth-year residents who were not exposed to the training intervention. The primary outcome was the difference in accuracy of fetal-head-position assessment on vaginal examination by third-year residents before and after ultrasound feedback training. Univariate and multivariate analyses were performed to identify factors associated with digital examination accuracy.

RESULTS

Overall, 390 examinations were performed. The accuracy of fetal-head-position assessments of third-year residents was 55% (53/96) before training, 65% (74/114) during training and 70% (63/90) after training, while that of fourth-year residents who did not undergo training was 52% (47/90) (P = 0.04). Fourth-year residents who did not undergo ultrasound training demonstrated similar baseline accuracy to that of third-year residents pretraining (52% (47/90) vs 55% (53/96), P = 0.68), but had significantly lower accuracy than had the third-year residents post-training (52% (47/90) vs 70% (63/90); P = 0.01). Multivariable analysis revealed a positive association between ultrasound feedback training and the ability to assess accurately fetal head position. After adjusting for the variables included in the final model, examinations performed by third-year residents pretraining and those performed by fourth-year residents who did not undergo training were less likely to be accurate than those performed by third-year residents post-training (adjusted odds ratio, 0.48 (95% CI, 0.26-0.91) and 0.42 (95% CI, 0.22-0.80), respectively).

CONCLUSION

Immediate ultrasound feedback training increased trainee accuracy in vaginal assessment of fetal head position in labor. Its integration into obstetric training programs should be considered. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of spontaneous vaginal delivery in nulliparous women with a prolonged second stage of labor: the value of intrapartum ultrasound

BACKGROUND

A limited number of studies have addressed the role of intrapartum ultrasound in the prediction of the mode of delivery in women with prolonged second stage of labor.

OBJECTIVE

The objective of the study was to evaluate the role of transabdominal and transperineal sonographic findings in the prediction of spontaneous vaginal delivery among nulliparous women with prolonged second stage of labor.

STUDY DESIGN

This was a 2-center prospective study conducted at 2 tertiary maternity units. Nulliparous women with a prolonged active second stage of labor, as defined by active pushing lasting more than 120 minutes, were eligible for inclusion. Transabdominal ultrasound to evaluate the fetal head position and transperineal ultrasound for the measurement of the midline angle, the head-perineum distance, and the head-symphysis distance were performed in between uterine contractions and maternal pushes. At transperineal ultrasound the angle of progression was measured at rest and at the peak of maternal pushing effort. The delta angle of progression was defined as the difference between the angle of progression measured during active pushing at the peak of maternal effort and the angle of progression at rest. The sonographic findings of women who had spontaneous vaginal delivery vs those who required obstetric intervention, either vacuum extraction or cesarean delivery, were evaluated and compared.

RESULTS

Overall, 109 were women included. Spontaneous vaginal delivery and obstetric intervention were recorded in 40 (36.7%) and 69 (63.3%) patients, respectively. Spontaneous vaginal delivery was associated with a higher rate of occiput anterior position (90% vs 53.2%, P < .0001), lower head-perineum distance and head-symphysis distance (33.2 ± 7.8 mm vs 40.1 ± 9.5 mm, P = .001, and 13.1 ± 4.6 mm vs 19.5 ± 8.4 mm, P < .001, respectively), narrower midline angle (29.6° ± 15.3° vs 54.2° ± 23.6°, P < .001) and wider angle of progression at the acme of the pushing effort (153.3° ± 19.8° vs 141.8° ± 25.7°, P = .02) and delta-angle of progression (17.3° ± 12.9° vs 12.5° ± 11.0°, P = .04). At logistic regression analysis, only the midline angle and the head-symphysis distance proved to be independent predictors of spontaneous vaginal delivery. More specifically, the area under the curve for the prediction of spontaneous vaginal delivery was 0.80, 95% confidence interval (0.69-0.92), P < .001, and 0.74, 95% confidence interval (0.65-0.83), P = .002, for the midline angle and for the head-symphysis distance, respectively.

CONCLUSION

Transabdominal and transperineal intrapartum ultrasound parameters can predict the likelihood of spontaneous vaginal delivery in nulliparous women with prolonged second stage of labor.

Narrow subpubic arch angle is associated with higher risk of persistent occiput posterior position at delivery

OBJECTIVE

To determine whether the subpubic arch angle (SPA) measured by three-dimensional ultrasound is associated with the fetal occiput position at delivery and the mode of delivery.

METHODS

Nulliparous women with an uncomplicated singleton pregnancy at ≥ 37 weeks' gestation were recruited from two tertiary centers between September 2013 and August 2015. All women underwent a three-dimensional transperineal ultrasound examination and the SPA was measured using the previously validated Oblique View Extended Imaging software. Data on the outcome of labor were obtained prospectively in all cases and the correlations between SPA and the fetal occiput position at delivery and the incidence of operative delivery were investigated.

RESULTS

Overall, 368 women were included in the study. Fetal position at delivery was occiput anterior in 339 (92.1%) cases and occiput posterior (OP) in 29 (7.9%) cases. A significantly narrower SPA was found in the OP group compared with the occiput anterior group (104.4 ± 16.8° vs 116.4 ± 11.9°; P < 0.0001). The SPA was significantly narrower in women requiring obstetric intervention compared with in women with a spontaneous vaginal delivery. From multivariable logistic regression analysis, SPA and maternal height appeared to be significant predictors of both the fetal occiput position at delivery and the risk of operative delivery. The best cut-off value of SPA for predicting an OP position at delivery was 90.5°.

CONCLUSION

A narrow SPA is associated with a higher risk of persistent OP position at delivery and of operative delivery. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Prospective multicenter study of ultrasound-based measurements of fetal head station and position throughout labor

OBJECTIVES

To assess the relationship between fetal head position and head station during labor, as measured using an ultrasound-based system, and the occurrence of occiput posterior (OP) position at delivery.

METHODS

This was an international prospective observational study including women who delivered between January 2009 and September 2013 in four centers: one in Brooklyn, NY, USA; one in Haifa, Israel; and two in Paris, France. We used an ultrasound-based system (LaborPro) to monitor fetal head station and position non-invasively throughout labor. We collected data on demographics, labor parameters and outcome.

RESULTS

A total of 595 women were included. In 563 (94.6%) women, fetal head position at delivery was occiput anterior (OA), in 31 (5.2%) it was OP and in one (0.2%) it was occiput transverse. In 89% of pregnancies with intrapartum OP when fetal head station was above -2, the head position turned to OA at delivery; the equivalent figures were 74% and 63% OA at delivery when intrapartum OP was diagnosed at head stations of -2 to < 0, and 0 and below, respectively. Cesarean delivery was performed in 35% of pregnancies with fetal head in OP position at delivery, as opposed to 10% of those with non-OP position at delivery. On retrospective analysis, all deliveries in OP were already in OP at station -2 and below.

CONCLUSIONS

In this first assessment of fetal head position at delivery according to fetal head position at various station levels, our data show that 100% of OP positions at delivery were already in OP position at station -2 and below. We did not observe rotation from a non-OP to an OP position from station -2 and below. Nearly two-thirds of fetuses in OP at station 0 and below will rotate to an OA position for delivery.