Sonographic assessment of fetal spine and head position during the first and second stages of labor for the diagnosis of persistent occiput posterior position: a pilot study

Prediction of persistent occiput posterior position by sonographic assessment of fetal head attitude at start of second stage of labor: prospective study

OBJECTIVES

To evaluate the relationship between the attitude of the fetal head quantified by means of the chin-to-chest angle (CCA) in fetuses in occiput posterior (OP) position at the beginning of the second stage of labor, and persistent OP position at birth.

METHODS

This was a single-center, prospective observational study conducted at the University Hospital of Parma, Parma, Italy. We included singleton pregnancies at term with fetuses in the OP position at the beginning of the second stage of labor. The fetal head position, station by means of angle of progression and head-to-perineum distance, and attitude by means of CCA were assessed using transabdominal or transperineal ultrasound. The primary outcome was persistent OP position at birth.

RESULTS

Between January and July 2022, 76 women were included in the study. There were 48 (63.2%) spontaneous rotations of the fetal head and spontaneous vaginal delivery occurred in all. Among the 28 (36.8%) fetuses that did not rotate spontaneously into an occiput anterior position, eight (28.6%) had a spontaneous vaginal delivery, while operative vaginal delivery and Cesarean delivery was performed in 11 (39.3%) and nine (32.1%) cases, respectively. Multivariable logistic regression analysis showed that the CCA (adjusted odds ratio (aOR), 2.15 (95% CI, 1.22-3.78); P = 0.008) and nulliparity (aOR, 0.20 (95% CI, 0.06-0.76); P = 0.02) were associated independently with persistent OP position at birth. Moreover, the CCA showed an area under the receiver-operating-characteristics curve of 0.69 (95% CI, 0.56-0.82); P = 0.005) for the prediction of persistent OP position. The optimal cut-off value of the CCA was 36.5°, and was associated with a sensitivity of 0.82 (95% CI, 0.63-0.94), specificity of 0.50 (95% CI, 0.35-0.65), positive predictive value of 0.49 (95% CI, 0.34-0.64), negative predictive value of 0.83 (95% CI, 0.64-0.94), positive likelihood ratio of 1.64 (95% CI, 1.18-2.29) and negative likelihood ratio of 0.36 (95% CI, 0.15-0.83).

CONCLUSIONS

Our data show that, within a population of women with fetal OP position at the beginning of the second stage of labor, the sonographic fetal head attitude measured by means of the CCA might help in the identification of fetuses at risk of persistent OP position. Such findings can be useful for patient counseling when OP position is diagnosed at full cervical dilatation. Further studies should investigate if the CCA might select patients who may benefit from manual rotation of the fetal head. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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.

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.

The correlation between levator ani co-activation and fetal head regression on maternal pushing at term

OBJECTIVE

To assess the correlation between fetal head regression and levator ani muscle (LAM) co-activation under Valsalva maneuver.

STUDY DESIGN

This study was a secondary analysis of a prospective cohort study on the association between the angle of progression (AoP) and labor outcome. We scanned a group of nulliparous women at term before the onset of labor at rest and under maximum Valsalva maneuver. In addition to the previously calculated AoP, in the present study, we measured the anteroposterior diameter of LAM hiatus (APD) on each ultrasound image. LAM co-activation was defined as APD at Valsalva less than that at rest, whereas fetal head regression was defined as AoP at Valsalva less than that at rest. We calculated the correlation between the two phenomena. Finally, we examined various labor outcomes according to the presence, absence, or co-existence of these two phenomena.

RESULTS

We included 469 women. A total of 129 (27.5%) women presented LAM co-activation while 50 (10.7%) showed head regression. Only 15 (3.2%) women showed simultaneous head regression and LAM co-activation. Women with coexisting LAM co-activation and head regression had the narrowest AoP at Valsalva in comparison with other study groups (p < .001). In addition, they had the highest risk of Cesarean delivery (40%) and longest first, second, and active second stage durations, although none of these reached statistical significance.

CONCLUSION

In nulliparous women at term before the onset of labor fetal head regression and LAM co-activation at Valsalva are two distinct phenomena that uncommonly coexist.

Intrapartum ultrasound in women with prolonged first stage of labor

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

The role of the angle of progression in the prediction of the outcome of occiput posterior position in the second stage of labor

BACKGROUND

Occiput posterior position is the most frequent cephalic malposition, and its persistence at delivery is associated with a higher risk of maternal and perinatal morbidity. Diagnosis and management of occiput posterior position remain a clinical challenge. This is partly caused by our inability to predict fetuses who will spontaneously rotate into occiput anterior from those who will have persistent occiput posterior position. The angle of progression, measured with transperineal ultrasound, represents a reliable tool for the evaluation of fetal head station during labor. The relationship between the persistence of occiput posterior position and fetal head station in the second stage of labor has not been previously assessed.

OBJECTIVE

This study aimed to evaluate the role of fetal head station, as measured by the angle of progression, in the prediction of persistent occiput posterior position and the mode of delivery in the second stage of labor.

STUDY DESIGN

We recruited a nonconsecutive series of women with posterior occiput position diagnosed by transabdominal ultrasound in the second stage of labor. For each woman, a transperineal ultrasound was performed to measure the angle of progression at rest. We compared the angle of progression between women who delivered fetuses in occiput anterior position and those with persistent occiput posterior position at delivery. Receiver operating characteristics curves were performed to evaluate the accuracy of the angle of progression in the prediction of persistent occiput posterior position. Finally, we performed a multivariate logistic regression to determine independent predictors of persistent occiput posterior position.

RESULTS

Overall, 63 women were included in the analysis. Among these, 39 women (62%) delivered in occiput anterior position, whereas 24 (38%) delivered in occiput posterior position (persistent occiput posterior position). The angle of progression was significantly narrower in the persistent occiput posterior position group than in women who delivered fetuses in occiput anterior position (118.3°±12.2° vs 127.5°±10.5°; P=.003). The area under the receiver operating characteristics curve was 0.731 (95% confidence interval, 0.594-0.869) with an estimated best cutoff range of 121.5° (sensitivity of 72% and specificity of 67%). On logistic regression analysis, the angle of progression was found to be independently associated with persistence of occiput posterior position (odds ratio, 0.942; 95% confidence interval, 0.889-0.998; P=.04). Finally, women who underwent cesarean delivery had significantly narrower angle of progression than women who had a vaginal delivery (113.5°±8.1 vs 128.0°±10.7; P<.001). The area under the receiver operating characteristics curve for the prediction of cesarean delivery was 0.866 (95% confidence interval, 0.761-0.972). At multivariable logistic regression analysis including the angle of progression, parity, and gestational age at delivery, the angle of progression was found to be the only independent predictor associated with cesarean delivery (odds ratio, 0.849; 95% confidence interval, 0.775-0.0930; P<.001).

CONCLUSION

In fetuses with occiput posterior at the beginning of the second stage of labor, narrower values of the angle of progression are associated with higher rates of persistent occiput posterior position at delivery and a higher risk of cesarean delivery.

When does fetal head rotation occur in spontaneous labor at term: results of an ultrasound-based longitudinal study in nulliparous women

BACKGROUND

Improved information about the evolution of fetal head rotation during labor is required. Ultrasound methods have the potential to provide reliable new knowledge about fetal head position.

OBJECTIVE

The aim of the study was to describe fetal head rotation in women in spontaneous labor at term using ultrasound longitudinally throughout the active phase.

STUDY DESIGN

This was a single center, prospective cohort study at Landspitali - The National University Hospital of Iceland, Reykjavík, Iceland, from January 2016 to April 2018. Nulliparous women with a single fetus in cephalic presentation and spontaneous labor onset at ≥37 weeks' gestation were eligible. Inclusion occurred when the active phase could be clinically established by labor ward staff. Cervical dilatation was clinically examined. Fetal head position and subsequent rotation were determined using both transabdominal and transperineal ultrasound. Occiput positions were marked on a clockface graph with 24 half-hour divisions and categorized into occiput anterior (≥10- and ≤2-o'clock positions), left occiput transverse (>2- and <4-o'clock positions), occiput posterior (≥4- and ≤8 o'clock positions), and right occiput transverse positions (>8- and <10-o'clock positions). Head descent was measured with ultrasound as head-perineum distance and angle of progression. Clinical vaginal and ultrasound examinations were performed by separate examiners not revealing the results to each other.

RESULTS

We followed the fetal head rotation relative to the initial position in the pelvis in 99 women, of whom 75 delivered spontaneously, 16 with instrumental assistance, and 8 needed cesarean delivery. At inclusion, the cervix was dilated 4 cm in 26 women, 5 cm in 30 women, and ≥6 cm in 43 women. Furthermore, 4 women were examined once, 93 women twice, 60 women 3 times, 47 women 4 times, 20 women 5 times, 15 women 6 times, and 3 women 8 times. Occiput posterior was the most frequent position at the first examination (52 of 99), but of those classified as posterior, most were at 4- or 8-o'clock position. Occiput posterior positions persisted in >50% of cases throughout the first stage of labor but were anterior in 53 of 80 women (66%) examined by and after full dilatation. The occiput position was anterior in 75% of cases at a head-perineum distance of ≤30 mm and in 73% of cases at an angle of progression of ≥125° (corresponding to a clinical station of +1). All initial occiput anterior (19), 77% of occiput posterior (40 of 52), and 93% of occiput transverse positions (26 of 28) were thereafter delivered in an occiput anterior position. In 6 cases, the fetal head had rotated over the 6-o'clock position from an occiput posterior or transverse position, resulting in a rotation of >180°. In addition, 6 of the 8 women ending with cesarean delivery had the fetus in occiput posterior position throughout the active phase of labor.

CONCLUSION

We investigated the rotation of the fetal head in the active phase of labor in nulliparous women in spontaneous labor at term, using ultrasound to provide accurate and objective results. The occiput posterior position was the most common fetal position throughout the active phase of the first stage of labor. Occiput anterior only became the most frequent position at full dilatation and after the head had descended below the midpelvic plane.

Intrapartum ultrasound at the initiation of the active second stage of labor predicts spontaneous vaginal delivery

BACKGROUND

Longer duration of active pushing during labor is associated with a higher rate of operative delivery and an increased risk of maternal and neonatal complications. Although immediate pushing at complete dilatation is associated with lower rates of chorioamnionitis and postpartum hemorrhage, it is also associated with a longer duration of pushing.

OBJECTIVE

This study aimed to evaluate whether fetal head station and position, as assessed by ultrasound at the beginning of the pushing process, can predict the mode of delivery and duration of pushing in nulliparous women.

STUDY DESIGN

This prospective observational study included nulliparous women with neuraxial analgesia and complete cervical dilatation. The following sonographic parameters were assessed just before the beginning of the pushing process, at rest, and while pushing during contraction: head position, angle of progression, head-perineum distance, and head-symphysis distance. The change between rest and pushing was designated as delta angle of progression, delta head-perineum distance, and delta head-symphysis distance. The sonographic measurements and fetal head station assessed by vaginal examination were compared between women who had a spontaneous vaginal delivery to those who underwent an operative delivery, and between those who pushed for more or less than 1 hour.

RESULTS

Of the 197 women included in this study, 166 (84.3%) had a spontaneous vaginal delivery, 31 (15.7%) had an operative delivery, 23 (11.6%) had a vacuum delivery, and 8 (4.0%) had a cesarean delivery. Spontaneous vaginal delivery and shorter duration of pushing (less than an hour) were significantly more common with a nonocciput posterior position (10.6% vs 47.3%; P<.005), a wider angle of progression, a shorter head-perineum distance and head-symphysis distance (both during rest and while pushing), and a lower fetal head station as assessed by digital vaginal examination. However, a logistic regression model revealed that only the angle of progression at rest and the delta angle of progression were independently associated with a spontaneous vaginal delivery with an area under the curve of 0.82 (95% confidence interval, 0.76-0.87; P<.0001) and 0.75 (95% confidence interval, 0.67-0.79; P<.0001), respectively.

CONCLUSION

Ultrasound performed at the beginning of the active second stage of labor can assist in predicting the mode of delivery and duration of pushing and perform better than the traditional digital examination, with the angle of progression at rest and delta angle of progression being the best predictors.

The value of intrapartum ultrasound in the prediction of persistent occiput posterior position: Systematic review and meta-analysis

OBJECTIVE

To determine whether ultrasound-assessed occiput posterior (OP) position during labor can predict OP position at delivery.

STUDY DESIGN

We performed a systematic literature search in PubMed, EMBASE and the Cochrane Library from inception to February 2019. Included studies needed to report both the fetal head position in labor, as assessed by ultrasound, and the corresponding actual occiput position at delivery. We used a bivariate mixed-effects model to synthesis data. We also calculated I² to test heterogeneity and explored the source of heterogeneity by meta-regression and subgroup analysis.

RESULTS

Sixteen primary articles were included in this meta-analysis. Overall sensitivity and specificity of intrapartum ultrasound for prediction of persistent OP position were 0.85 (95%CI: 0.67 to 0.94) and 0.83 (95%CI: 0.77 to 0.87), respectively. The area under the receiver operating characteristic curve was 0.89 (95%CI: 0.86 to 0.91). Substantial heterogeneity was detected (I² = 98, 95%CI: 97-99), and the labor stage at ultrasound examination may be the source of heterogeneity (P = 0.00). After the stratification by extent of cervical dilatation, the predictive sensitivity and specificity at cervical dilatation ≥4 cm reached 0.92 (95%CI: 0.85 to 0.99) and 0.85 (95%CI: 0.80 to 0.91), respectively.

CONCLUSION

Intrapartum ultrasound is a helpful tool for predicting persistent OP position, but the results of the test, especially the ultrasound examination before or at the beginning of labor, must be interpreted with caution. Re-evaluation at late labor is usually necessary.

How reliable is fetal occiput and spine position assessment prior to induction of labor?

OBJECTIVES

To assess the reliability of fetal occiput and spine position determination in nulliparous women prior to induction of labor (IOL), and to evaluate identification of fetal occiput and spine positions prior to IOL in the prediction of labor outcome.

METHODS

A series of 136 nulliparous women were recruited prospectively, immediately after the decision to perform IOL was made. Transabdominal ultrasound was performed to determine fetal head and spine positions. After at least 1 h, and prior to IOL, fetal occiput and spine positions were reassessed. Fetal occiput and spine positions were then compared between women who underwent vaginal delivery and those who delivered by Cesarean section.

RESULTS

On the first and second assessments, respectively, fetal occiput position was anterior in 55 (40.4%) and 62 (45.6%) women, transverse in 52 (38.2%) and 49 (36.0%) women, and posterior in 29 (21.3%) and 25 (18.4%) women, while fetal spine position was anterior in 58 (42.6%) and 52 (38.2%) women, transverse in 42 (30.9%) and 50 (36.8%) women, and posterior in 36 (26.5%) and 34 (25.0%) women. Discordance between the first and second assessments of fetal occiput position was identified in 34 (25.0%) women, whereas discordance of fetal spine position was observed in 40 (29.4%) women. The incidence of fetal occiput posterior position in women undergoing Cesarean section was comparable to that in the vaginal-delivery group (19 (18.8%) vs 6 (17.1%); P = 0.826), which was similarly the case for fetal posterior spine position (27 (26.7%) vs 7 (20%); P = 0.428). Women with fetal occiput posterior position had a longer induction-to-delivery interval in comparison to those with non-occiput posterior fetal position (1786 ± 805 vs 1347 ± 784 min; P = 0.013).

CONCLUSIONS

Fetal occiput and spine positions are dynamic in a considerable proportion of women undergoing IOL, and their assessment does not seem to correlate with mode of delivery. Occiput and spine position assessment in women prior to IOL is unlikely to be clinically useful. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Intrapartum ultrasound monitoring of malposition and malrotation during labor neuraxial analgesia: maternal outcomes

Objective: This study analyzes the important role of ultrasonography (IUS) related to the maternal outcomes in women with fetal persistent occiput posterior position (POPP) and asynclitism (A) in labor neuraxial analgesia (LNA).Study design: Prospective assessment of 148 primiparous women diagnosed with the prolonged second stage of labor. Transabdominal and transperineal IUS were used to detect fetal head position and to evaluate the angle of progression (AOP) and pubic arch angle (PAA). Statistical data about maternal aspects, modalities of delivery and maternal outcomes were observed.Results: In all parturients included in the study, the operative delivery rate was 73%. In patients delivered via cesarean section, the PAA was ≤ of 96.5°. There was statistical correlation between doses of LNA and Apgar score at first minute (r0.8).Conclusions: There is a greater frequency of Fetal POPP and asynclitism related with maternal complications. The results of our study confirmed the importance of determination of angle of progression (AoP) and PAA in the prolonged second stage of labor. Unfavorable AoP and PAA, in presence of POPP and A, are related with high percentage of operative delivery. If the prolonged labor and delivery in these patients exceed time limit proposed by American College of Obstetricians and Gynecologists guidelines, it may be viewed as a possible malpractice. In cases of POPP with asynclitism, in the second stage of labor detected by IUS it is advisable to discontinue the anesthetic drugs administration in LNA; because the labor pain is related to the dystocia, an operative delivery is necessary to avoid maternal and fetal complications.

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.

Case Report of Spontaneous Skull Fracture in a Newborn With Cesarean Birth for Persistent Occiput Posterior Position

Spontaneous newborn skull fracture is rarely cited in nursing literature as a potential outcome of persistent fetal occiput posterior position. Although most newborns seem unaffected by the condition initially, some may show symptoms several hours after the birth, when nursing assessments are less frequent. This case report illustrates delayed newborn symptoms that led to an unexpected diagnosis of spontaneous skull fracture.

Fetal rotation during vacuum extractions for prolonged labor: a prospective cohort study

INTRODUCTION

The aim of the study was to investigate fetal head rotation during vacuum extraction.

MATERIAL AND METHODS

We conducted a prospective cohort study from November 2013 to July 2016 in seven European hospitals. Fetal head position was determined with transabdominal or transperineal ultrasound and categorized as occiput anterior (OA), occiput transverse (OT) or occiput posterior (OP) position. Main outcome was the proportion of fetuses rotating during vacuum extraction. Secondary outcomes were conversion of delivery method, duration of vacuum extraction, umbilical artery pH <7.10 and agreement between clinical and ultrasound assessments.

RESULTS

The study population comprised 165 women. During vacuum extraction 117/119 (98%) remained in OA and two fetuses rotated to OP position. Rotation from OT to OA position occurred in 14/19 (74%) and to OP position in 5/19 (26%). Rotation from OP to OA position occurred in 15/25 (60%), and 10/25 (40%) fetuses remained in OP position. Delivery information was missing in two cases. The conversion rate from vacuum extraction to cesarean section or forceps was 10% in the OA group vs. 23% in the non-OA group; p < 0.05. The estimated duration of vacuum extraction was significantly shorter in OA fetuses, 7 min vs. 10 min (log rank test p < 0.01). There was no significant difference in umbilical artery pH < 7.10 between OA and non-OA position. Cohens Kappa of agreement between clinical and ultrasound assessments was 0.42 (95% CI 0.26-0.57).

CONCLUSION

Most fetuses in OP or OT positions rotated to OA position during vacuum extraction, but the proportion of failed vacuum extractions remained high.

The use of intrapartum ultrasound to diagnose malpositions and cephalic malpresentations

Fetal malpositions and cephalic malpresentations are well-recognized causes of failure to progress in labor. They frequently require operative delivery, and are associated with an increased probability of fetal and maternal complications. Traditional obstetrics emphasizes the role of digital examinations, but recent studies demonstrated that this approach is inaccurate and intrapartum ultrasound is far more precise. The objective of this review is to summarize the current body of literature and provide recommendations to identify malpositions and cephalic malpresentations with ultrasound. We propose a systematic approach consisting of a combination of transabdominal and transperineal scans and describe the findings that allow an accurate diagnosis of normal and abnormal position, flexion, and synclitism of the fetal head. The management of malpositions and cephalic malpresentation is currently a matter of debate, and individualized depending on the general clinical picture and expertise of the provider. Intrapartum sonography allows a precise diagnosis and therefore offers the best opportunity to design prospective studies with the aim of establishing evidence-based treatment. The article is accompanied by a video that demonstrates the sonographic technique and findings.

Sonographic evaluation of the fetal spine position and success rate of manual rotation of the fetus in occiput posterior position: A randomized controlled trial

BACKGROUND

To evaluate whether sonographic (US) diagnosis of the fetal spine position could increase the success rate of manual rotation of the fetal occiput (MRFO) in second-stage arrest in persistent occiput posterior position (OPP).

METHODS

In this randomized controlled parallel single-center trial, 58 nulliparous in second-stage arrest of labor with fetus in cephalic presentation and OPP diagnosed by US were randomly assigned to group A where the fetal spine position was not known by the operator or to group B where the operator knew it. The main outcome was the success of MRFO in the two groups. Secondary outcomes were perineal injuries, blood loss, duration of expulsive period, and neonatal APGAR at 5 minutes.

RESULTS

A priori knowledge of the spine position improves the success of the MRFO (41.4% group A versus 82.8% group B, p value < 0.001), the percentage of spontaneous deliveries (27.6% group A versus 69% group B, p value = 0.01), and maternal outcome (intact perineum and blood loss). No differences were detected on the neonatal side.

CONCLUSIONS

MRFO is a safe and useful procedure that should be performed in second-stage arrest in OPP. A better performance was observed when supported by the US knowledge of the spine position. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:472-476, 2017.

The "occiput-spine angle": a new sonographic index of fetal head deflexion during the first stage of labor

BACKGROUND

Fetal head "attitude" (relationship of fetal head to spine) in the first stage of labor may have a substantial impact on labor outcome. The diagnosis of fetal head deflexion traditionally is based on digital examination in labor, although the use of ultrasound to support clinical diagnosis has been recently reported.

OBJECTIVES

The aims of this study were: (1) to quantify the degree of fetal head deflection via the use of sonography during the first stage of labor; and (2) to determine whether a parameter derived from ultrasound examination (the occiput-spine angle) has a relationship with the course and outcome of labor.

STUDY DESIGN

This was a prospective multicentric, cross-sectional study conducted at the Maternity Unit of the University of Bologna and Parma from January 2014 to April 2015. A nonconsecutive series of women with uncomplicated singleton pregnancies at term gestation (37 weeks or more) were submitted to transabdominal ultrasound during the first stage of labor. If fetal position was occiput anterior or transverse, the angle between the fetal occiput and the cervical spine (the occiput-spine angle) was sonographically obtained on the sagittal plane. The measurements of the occiput spine-angle were performed offline by 2 operators who were blinded to the labor outcome. The intra- and interobserver reproducibility and the correlation between the occiput-spine angle and the mode of delivery were evaluated.

RESULTS

A total of 108 pregnant women were recruited, 79 of which underwent a spontaneous vaginal delivery and 29 were submitted to obstetric intervention (19 cesarean delivery and 10 instrumental vaginal deliveries). The mean value of the occiput-spine angle measured in the active phase of the first stage was 126° ± 9.8° (SD). The occiput-spine angle measurement showed a very good intraobserver (r = 0.86; 95% confidence interval [95% CI] 0.80-0.90) and a fair-to-good interobserver (r = 0.64; 95% CI 0.51-0.74) agreement. The occiput-spine angle was significantly narrower in women who underwent obstetric intervention (cesarean or vacuum delivery) due to labor arrest (121° ± 10.5° vs 127° ± 9.4°, P = .03). Multivariable logistic regression analysis showed that narrow occiput-spine angle values (OR 1.08; 95% CI 1.00-1.16; P = .04) and nulliparity (OR 16.06; 95% CI 1.71-150.65; P = .02) were independent risk factors for operative delivery. A larger occiput-spine angle width (i.e., >125°) showed to be significantly associated with a shorter duration of labor (hazard ratio = 1.62; 95% CI 1.07-2.45; P = .02).

CONCLUSION

We described herein the "occiput-spine angle," a new sonographic parameter to assess fetal head deflection during labor. Fetuses with smaller occiput-spine angle (<125°) are at increased risk for operative delivery.

Sonographic assessment of fetal occiput position during labor for the prediction of labor dystocia and perinatal outcomes

OBJECTIVES

To evaluate the effect of the occiput posterior (OP) position on dystocia and perinatal outcomes.

METHODS

This was a prospective cohort study of 162 primiparous women. We performed intrapartum sonography, and fetal occiput positions were recorded. The relationships between the position of the occiput and the course of labor and perinatal outcomes were investigated. Statistical analysis was performed using SAS 9.2.

RESULTS

Fifty-six of 162 fetuses were found to be in the OP position during the first stage of labor. Eight (80.0%) of 10 fetuses in the OP position during the second stage were among the 56 that were in OP position during the first stage. The rate of cesarean sections performed in the OP position group during the first stage was significantly higher than the rate in the non-OP position group (37.5% versus 8.5%, p < 0.0001). The duration of the second stage of labor was longer and neonatal complications occurred more frequently in the OP position group during the second stage than in the non-OP position group (77.9  ±  33.4 min versus 52.2  ± 26.6 min, p = 0.0104; 50.0% versus 17.2%, p = 0.0118).

CONCLUSIONS

The OP position may be a useful predicator for labor dystocia that can lead to poor neonatal outcomes.

Prevention of primary caesarean delivery: comprehensive management of dystocia in nulliparous patients at term

PURPOSE

Dystocia is the leading indication for primary caesarean sections. Our aim is to compare two approaches in the management of dystocia in labor in nulliparous women with a singleton fetus in cephalic presentation at term in spontaneous or induced labor.

METHODS

Prospective cohort study. Four hundred and nineteen consecutive patients were divided into two groups: the standard management group (SM), in acceleration of labor was commenced at the "action line" in the case of arrested or protracted labor, and the comprehensive management group (CM) in which arrested or protracted labor was considered as a warning sign promoting further diagnostic assessment prior to considering intervention.

RESULTS

Caesarean sections rate was 22.2 % in the SM group (216 patients) and 10.3 % in the CM group (203 patients) (p = 0.001). The rate of oxytocin use decreased from 33.3 % in SM group to 13.8 % in the CM group (p < 0.0005). The rate of amniotomy decreased from 41.7 % in the SM group to 7.4 % in the CM group (p < 0.0005). The percentage of newborns with 5-min Apgar score <7 and/or umbilical cord arterial pH ≤ 7.00 decreased from 2.3 % in SM cohort to 0.5 % in CM cohort (p = ns). The average length of labor did not differ between the two groups of patients (264 vs 277 min; p = ns).

CONCLUSION

Comprehensive management of dystocia enabled us to achieve a reduction in iatrogenic interventions in labor while maintaining good neonatal outcomes.

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.

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.

Intrapartum sonographic signs: new diagnostic tools in malposition and malrotation

In the past years, numerous studies have been published on the use of ultrasound during labor, showing this is an effective, accurate and objective tool for the assessment of the fetal head position and station. Literature affirmed that traditional transvaginal digital examination is highly subjective and dependent on the operator's experience. On the contrary, the use of intrapartum suprapubic transabdominal ultrasound can improve accuracy in determination of fetal head position and the precise knowledge of the location of specific fetal head landmarks in relationship to maternal pelvis. Intrapartum ultrasound will assist obstetricians in the diagnosis of normal labor progression, suggesting when medical and or operative intervention should be taken in case of complications. During each fetal head movement, there is a very specific relationship between fetal head landmarks and well-identified maternal structures, so the ultrasound diagnosis is performed step by step. In this review, we summarized the clinical situation of the fetal head in the pelvis and the relative ultrasonographic signs. Moreover, we collected all the ultrasonographic measures to diagnose the fetal head progression and rotations in the birth canal.

Progression of cervical dilatation in normal human labor is unpredictable

INTRODUCTION

The aim of this study was to analyze how the progression of cervical dilatation in active labor can be predicted by digital assessment in low-risk pregnant women, in spontaneous labor at term.

MATERIAL AND METHODS

This prospective observational study was performed on 328 women with singleton term gestations experiencing midwife-led labor according to local protocols, progressing to full dilatation and spontaneous delivery without any medical intervention. Mixed nonlinear models were adopted to (i) model individual cervical data into centile curves and (ii) calculate the time needed to gain 1 cm in cervical dilatation (TNG1cm ) modeled as a function of current dilatation. We correlated the first and the last TNG1cm on parturients with at least four cervical data points.

RESULTS

TNG1cm showed large variations, both before and after 6 cm. This variability of natural progression of cervical curves described by the 10th and 90th centiles exceeded the differences observed in published curves from cohorts homogeneous for parity, weight and ethnicity. There was no significant correlation between the first and the last TNG1cm . Neonatal base excess was not significantly different in women with TNG1cm <10th centile and >90th centile.

CONCLUSIONS

The rate of cervical dilatation, traced by parsimonious nonlinear mixed models, is largely unpredictable in the case of spontaneous naturally progressing labor, even when possible larger individual variability is excluded by prudent clinical rules. Future research in labor and delivery should be focused on the diagnosis of the causes that lie behind apparently erratic cervical changes.

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.

Is it possible to detect malposition of the vertex at an early stage in labour? A case-control study

OBJECTIVES

The aim of this study was to investigate if there are clinical signs which allow detection of malposition of the vertex on admission to the delivery unit, or when crossing the action line on the partogram.

STUDY DESIGN

Case-control study from 2007 to 2010 conducted on the delivery unit of Nordland Hospital, Bodø. Labours with malposition of the vertex (n = 171) were compared with a group with normal vertex presentation (n = 165). The positive predictive value was estimated for each sign using Bayes' rule.

MAIN OUTCOME MEASURES

Magnitude of positive predictive value for each clinical sign.

RESULTS

The positive predictive values for malposition were 9% if the foetus were in a right position, 11% if the labour was induced, 5% if the foetus was above the ischial spines, 4% if the reason for admission was contractions and 6% if cervix was <3 cm.

CONCLUSION

The ability of clinical assessment to predict malposition, either on admission or when crossing the action line on the partogram, was poor. Diagnosing malposition of the vertex requires other methods with a higher predictive value.

Intrapartum ultrasound: A useful method for evaluating labor progress and predicting operative vaginal delivery

The last step of a successful pregnancy is the safe delivery of the fetus. An important question is if the delivery should vaginal or operative. In addition to the use of conventional antenatal ultrasound, the use of intrapartum ultrasound to evaluate fetal head station, position, cervical ripening, and placental separation is promising. This review evaluates and summarizes the usefulness of intrapartum ultrasound for the evaluation of labor progress and predicting successful operative vaginal delivery.

The outcome of midwife-led labor in low-risk women within an obstetric referral unit

OBJECTIVE

To analyze maternal and neonatal outcomes of midwife-led labor in low-risk women at term.

METHODS

Prospective observational cohort of 1788 singleton low-risk pregnancies in spontaneous term labor, managed according to a specific midwife-led labor protocol. Primary outcomes were mode of delivery, episiotomy, 3rd-4th degree lacerations, post-partum hemorrhage (PPH), need for blood transfusions, pH and Apgar score and NICU admissions.

RESULTS

A total 1754 low-risk women (50.3% of all deliveries) were included in the analysis. Epidural analgesia was performed in 29.8% of cases. The rate of cesarean section was 3.7%. Episiotomy was performed in 17.6% of women. PPH > 1000 ml occurred in 1.7% of cases. 3.2% and 0.3% of the cases had an Apgar score <7 and pH < 7.10, respectively, while 0.3% of the newborns were admitted to NICU. Consultant-led labor was required for emerging risk factors during 1st and 2nd stage of labor in 16.1 and 8.6% of cases, respectively. Although maternal outcome were worse in women with emerging risk factors in labor, while neonatal outcomes were not affected by the presence these complications.

CONCLUSIONS

In hospital settings, midwife-led labor in low-risk women might unfold its major advantages without additional risks of medicalization for the mother and the neonate.

Intrapartum ultrasound assessment of fetal spine position

We investigated the role of foetal spine position in the first and second labour stages to determine the probability of OPP detection at birth and the related obstetrical implications. We conducted an observational-longitudinal cohort study on uncomplicated cephalic single foetus pregnant women at term. We evaluated the accuracy of ultrasound in predicting occiput position at birth, influence of fetal spine in occiput position during labour, labour trend, analgesia request, type of delivery, and indication to CS. The accuracy of the foetal spinal position to predict the occiput position at birth was high at the first labour stage. At the second labour stage, CS (40.3%) and operative vaginal deliveries (23.9%) occurred more frequently in OPP than in occiput anterior position (7% and 15.2%, resp.), especially in cases of the posterior spine. In concordant posterior positions labour length was greater than other ones, and analgesia request rate was 64.1% versus 14.7% for all the others. The assessment of spinal position could be useful in obstetrical management and counselling, both before and during labour. The detection of spinal position, more than OPP, is predictive of successful delivery. In concordant posterior positions, the labour length, analgesia request, operative delivery, and caesarean section rate are higher than in the other combination.

Association between fetal position at onset of labor and mode of delivery: a prospective cohort study

OBJECTIVES

To determine the association between fetal position at onset of labor and mode of delivery, specifically left occipito-anterior (LOA) fetal position and spontaneous vaginal delivery (SVD).

METHODS

All nulliparous women who were booked at the Birmingham Women's NHS Foundation Trust over an 18-month period from April 2007 to September 2008 with a singleton live fetus without structural anomalies at term gestation were invited to take part in the study. Women recruited to the study underwent a transabdominal ultrasound scan to determine fetal occiput position at the onset of labor. They were then followed up until birth to determine outcome. The primary outcome measure was mode of delivery, categorized into SVD, instrumental delivery and Cesarean section.

RESULTS

Of 1647 eligible women, 1250 had valid scans at onset of labor; 155 of the 1250 (12.4%) had fetuses in the LOA position. Analysis showed no evidence of difference in odds ratio (OR) of SVD for fetuses in the LOA position compared with all other positions (OR 0.864 (95% CI, 0.617-1.209); P = 0.394). No difference remained with adjustment for confounding effects of variables known to influence mode of delivery (OR 0.837 (95% CI, 0.551-1.272); P = 0.405). No other occipital position showed significant association with SVD. There was no evidence of the LOA position being associated with Cesarean section, ventouse or forceps delivery.

CONCLUSION

There is no evidence of an association between the fetal LOA position at onset of labor and SVD. This finding challenges the conventional theory that LOA is the optimum fetal position at onset of labor, and suggests that antenatal practices encouraging adoption of the LOA position through maternal posturing are unnecessary.

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.

Intrapartum sonographic assessment of labor

Fetal head progression during labor is difficult to assess. Digital examination has been shown to be an inaccurate method. Utilizing the ultrasound technology in the delivery room can standardize the way we assess head progression. Intrapartum ultrasound is applicable, for the assessment of the progression of labor and assists the obstetrician, in decision making regarding the need for an assisted delivery. This article summarizes the latest studies regarding the usage of ultrasound in the delivery room and the measurements that are used during delivery.

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.