Pubic arch angle in prolonged second stage of labor: clinical significance

Rebozo and advanced maternal postures: A promising set of intrapartum interventions to reduce persistent occiput posterior position of the fetal head

INTRODUCTION

Spinning Babies® procedures and the Rebozo technique have been recently implemented as additional interventions in laboring women with a fetus in occiput posterior position (OPP) to favor the rotation to an anterior position, which improve birth experience and health outcomes. Our study aimed to compare the probability of occurrence of persistent OPP (POPP) of the fetal head at the second stage of labor between retrospective and prospective cohorts and to assess associated sociodemographic, obstetric and intrapartum factors.

METHODS

We conducted a combined prospective and retrospective cohort study including 1500 women giving birth in 2017 (retrospective cohort) and 779 between 15 May and 15 December 2023 (prospective cohort). Each cohort was divided into two sub-cohorts depending on presence of OPP. Primary outcomes were compared the probability of occurrence of POPP in the two OPP sub-cohorts by a log binomial regression and logistic regression. A p<0.05 was considered statistically significant. Data analysis was performed using Stata/MP18.0.

RESULTS

The proportion of OPP at the onset of labor was similar between the two cohorts (34.9% vs 35.1%). The probability of occurrence of POPP was significantly lower in the prospective OPP sub-cohort (27.7%, n=65/235) compared to the retrospective OPP sub-cohort (35.8%, n=154/430) (risk difference, RD= -0.081; 95% CI: -0.15 - -0.008; p=0.031). In the retrospective OPP sub-cohort, maternal age ≥35 years (RD=0.096; 95% CI: 0.001-0.190, p=0.044) and nulliparity (RD= -0.100; 95% CI: -0.190 - -0.001, p=0.036) were significantly associated with the probability of POPP.

CONCLUSIONS

Our findings suggest a potential benefit of a set of interventions combining Spinning Babies® and the Rebozo technique in decreasing the probability of POPP.

Inconsistent definitions of prolonged labor in international literature: a scoping review

Objective

Prolonged labor is the commonest indication for intrapartum cesarean section, but definitions are inconsistent and some common definitions were recently found to overestimate the speed of physiological labor. The objective of this review is to establish an overview of synonyms and definitions used in the literature for prolonged labor, separated into first and second stages, and establish types of definitions used.

Data sources

A systematic search was conducted in PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier.

Study eligibility criteria

All articles in English that (1) attempted to define prolonged labor, (2) included a definition of prolonged labor, or (3) included any synonym for prolonged labor, were included.

Methods

Data on study design, year of publication, country or region of origin, synonyms used, definition of prolonged first and/or second stage, and origin of provided definition (if not primarily established by the study) were collected into a database.

Results

In total, 3402 abstracts and 536 full-text papers were screened, and 232 papers were included. Our search established 53 synonyms for prolonged labor. Forty-three studies defined prolonged labor and 189 studies adopted a definition of prolonged labor. Definitions for prolonged first stage of labor were categorized into: time-based (n=14), progress-based (n=12), clinician-based (n=5), or outcome-based (n=4). For the 33 studies defining prolonged second stage, the majority of definitions (n=25) were time-based, either based on total duration or duration of no descent of the presenting part.

Conclusions

Despite efforts to arrive at uniform labor curves, there is still little uniformity in definitions of prolonged labor. Consensus on which definition to use is called for, in order to safely and respectfully allow physiological labor progress, ensure timely management, and assess and compare incidence of prolonged labor between settings.

Descent of the presenting part assessed with ultrasound

Fetal head descent can be expressed as fetal station and engagement. Station is traditionally based on clinical vaginal examination of the distal part of the fetal skull and related to the level of the ischial spines. Engagement is based on a transabdominal examination of the proximal part of the fetal head above the pelvic inlet. Clinical examinations are subjective, and objective measurements of descent are warranted. Ultrasound is a feasible diagnostic tool in labor, and fetal lie, station, position, presentation, and attitude can be examined. This review presents an overview of fetal descent examined with ultrasound. Ultrasound was first introduced for examining fetal descent in 1977. The distance from the sacral tip to the fetal skull was measured with A-mode ultrasound, but more convenient transperineal methods have since been published. Of those, progression distance, angle of progression, and head-symphysis distance are examined in the sagittal plane, using the inferior part of the symphysis pubis as reference point. Head-perineum distance is measured in the frontal plane (transverse transperineal scan) as the shortest distance from perineum to the fetal skull, representing the remaining part of the birth canal for the fetus to pass. At high stations, the fetal head is directed downward, followed with a horizontal and then an upward direction when the fetus descends in the birth canal and deflexes the head. Head descent may be assessed transabdominally with ultrasound and measured as the suprapubic descent angle. Many observational studies have shown that fetal descent assessed with ultrasound can predict labor outcome before induction of labor, as an admission test, and during the first and second stage of labor. Labor progress can also be examined longitudinally. The International Society of Ultrasound in Obstetrics and Gynecology recommends using ultrasound in women with prolonged or arrested first or second stage of labor, when malpositions or malpresentations are suspected, and before an operative vaginal delivery. One single ultrasound parameter cannot tell for sure whether an instrumental delivery is going to be successful. Information about station and position is a prerequisite, but head direction, presentation, and attitude also should be considered.

Maternal postures for fetal malposition in late pregnancy for improving the health of mothers and their infants

BACKGROUND

The optimal relationship of the fetus to the mother's birth canal is when the fetus is in the longitudinal lie, cephalic presentation with well-flexed head (vertex presentation), and in the occipito-anterior position. Fetal malposition is described as occipito-posterior (OP) when the back of the fetal head lies posteriorly in the mother's pelvis, and occipito-transverse (OT) when the back of the fetal head lies transversely in the mother's pelvis. The fetal head will often be deflexed and may extend further to a mento-anterior or mento-transverse position, where the chin is anterior or transverse to the maternal pelvis. Fetal malposition is associated with both maternal and fetal complications, including prolonged labour, fetal distress, maternal exhaustion, need for caesarean section, operative vaginal birth, and increased risk of perineal trauma and anal sphincter injuries. This review considered positional interventions in late pregnancy to correct fetal malposition. A separate Cochrane review addresses maternal postural position for fetal malposition during labour.

OBJECTIVES

To assess the effects of maternal posture for fetal malposition in women in late pregnancy.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (24 October 2022), and reference lists of retrieved studies.

SELECTION CRITERIA

Our selection criteria were randomised controlled trials and cluster-randomised controlled trials that included women in late pregnancy with a malposition of the fetus including OP and OT, mento-anterior and mento-transverse, or with uncertain fetal position, randomly allocated to use of specified maternal positioning in late pregnancy, compared with usual care.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed potential studies for inclusion in the review. We used standardised methodology for assessment of risk of bias and trustworthiness developed by the Cochrane Pregnancy and Childbirth Group.

MAIN RESULTS

We reviewed three full-text reports; we excluded one due to lack of a comparison group and listed two as awaiting classification. We needed further information from the report authors for both potentially suitable studies to account for substantial imbalances between the numbers allocated to each group in one, or identical numbers for all groups in the other. The failure to resolve these issues may have been due to the long interval since publication of the studies (2004 and 1983).

AUTHORS' CONCLUSIONS

We did not identify evidence for guiding practice with respect to positional interventions for fetal malposition in late pregnancy. More studies are needed to understand the effect of positional interventions in late pregnancy. Future research on positional interventions for fetal malposition in late pregnancy should include follow-up to determine whether short-term correction of fetal position translates to improved pregnancy outcomes. This might include interventions commenced in late pregnancy and repeated as needed until the onset of labour. The latter would be included in the review on maternal positions during labour.

Predictive value of the trans-perineal three-dimensional ultrasound measurement of the pubic arch angle for vaginal delivery

BACKGROUND

Numerous variables are linked to the success of vaginal delivery, including the subpubic arch angle (SPAA) during labor, the importance of which has not yet been fully elucidated.

AIM

To examine the SPAA distributional characteristics and to ascertain SPAA's ability to predict the type and duration of labor.

METHODS

We determined the SPAA and analyzed the corresponding data. We also evaluated the relationship between the SPAA and the mode of delivery and the duration of labor by regression. The present study comprised a total of 301 pregnant women who had given birth at Beijing Tiantan Hospital of the Capital Medical University between January and December of 2021.

RESULTS

Our analysis of 301 pregnant women revealed that the SPAA measured using three-dimensional trans-perineal ultrasound had a minimum angle of 81° and a maximum angle of 122.2°. The angle in the normal vaginal delivery group was greater than that in the labor cesarean group (P = 0.000). The SPAA was a highly significant positive predictor of normal vaginal delivery (P = 0.000) with an area under the curve of 0.782 (P = 0.000; 95%CI: 0.717-0.848). We found the length of the second stage of labor to be positively influenced by the SPAA using linear regression analysis (P = 0.045).

CONCLUSION

The SPAA was a highly significant positive predictor of normal vaginal delivery. The length of the second stage of labor and normal vaginal birth were predicted by SPAA.

Predictive value of the trans-perineal three-dimensional ultrasound measurement of the pubic arch angle for vaginal delivery

BACKGROUND

Numerous variables are linked to the success of vaginal delivery, including the subpubic arch angle (SPAA) during labor, the importance of which has not yet been fully elucidated.

AIM

To examine the SPAA distributional characteristics and to ascertain SPAA’s ability to predict the type and duration of labor.

METHODS

We determined the SPAA and analyzed the corresponding data. We also evaluated the relationship between the SPAA and the mode of delivery and the duration of labor by regression. The present study comprised a total of 301 pregnant women who had given birth at Beijing Tiantan Hospital of the Capital Medical University between January and December of 2021.

RESULTS

Our analysis of 301 pregnant women revealed that the SPAA measured using three-dimensional trans-perineal ultrasound had a minimum angle of 81° and a maximum angle of 122.2°. The angle in the normal vaginal delivery group was greater than that in the labor cesarean group (P = 0.000). The SPAA was a highly significant positive predictor of normal vaginal delivery (P = 0.000) with an area under the curve of 0.782 (P = 0.000; 95%CI, 0.717–0.848). We found the length of the second stage of labor to be positively influenced by the SPAA using linear regression analysis (P = 0.045).

CONCLUSION

The SPAA was a highly significant positive predictor of normal vaginal delivery. The length of the second stage of labor and normal vaginal birth were predicted by SPAA.

Correlation between bituberous diameter and mode of delivery in a cohort of low-risk nulliparous women

OBJECTIVE

The aim our study was to evaluate the association between the antepartum clinical measurement of the Bituberous Diameter (BTD) and the occurrence of unplanned obstetrical intervention (UOI) due to labor dystocia, including either operative vaginal delivery or caesarean section in a cohort of low-risk, nulliparous at term.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Tertiary maternity care.

INTERVENTIONS

With the women lying in lithotomic the distance between two ischial tuberosities was assessed using a tape measure during the routine antenatal booking between 37 and 38 weeks of gestation.

MEASUREMENTS AND FINDINGS

Overall, 116 patient were included, and of these 23(19.8%) were submitted to an UOI due to labor dystocia. Compared to women that had a spontaneous vaginal delivery, women submitted to an UOI had a shorter BTD (8.25 + 0.843 vs 9.60 + 1.12, p < 0.001), a higher frequency of epidural analgesia (21/23 or 91.3% vs 50/93 or 53.8%; p = 0.002) and of augmentation of labor (14/23 or 60.9% vs 19/93 or 20.4%; p < 0.001) as well as a longer first [455 (IQR 142-455 min vs 293 (IQR 142-455) min] and second stages of labor [129 (IQR 85-155) min vs 51 (IQR 27-78) min]. Multivariable logistic regression showed that the BTD (aOR 0.16, 95% CI 0.04-0.60; p = 0.007) and the length of the second stage of labor (aOR 6.83, 95% CI 2.10-22.23; p = 0.001) were independently associated with UOI. When evaluating the diagnostic accuracy of the BTD for the prediction of UOI due to labor dystocia, the BTD showed an AUC of 0.82 (95 %CI 0.73-0.91; p < 0.001) with an optimal cut-off value of 8.6 cm (78.3% (95 %CI 56.3-92.5) sensitivity, 77.4% (95 %CI 67.6-85.4) specificity, 46.2% (95% CI 30.1-62.8) PPV, 93.5% (95% CI 85.5-97.9) NPV, 3.5 (95% CI 2.3-5.4) positive LR, and 0.28 (95% CI 0.13-0.61) negative LR. A significant inverse correlation between the length of the second stage of labour and the BTD in patients that had a vaginal delivery was also demonstrated (Spearman's rho = -0.24, p = 0.01).

KEY CONCLUSIONS

Our study suggests that antepartum clinical assessment of the BTD might be used as a reliable predictor of UOI due to labor dystocia in low-risk, nulliparous women at term gestation.

IMPLICATIONS FOR PRACTICE

Antenatal identification of women at higher risk for labor dystocia might trigger some interventions during the second stage of labor, such as maternal position shifting, to increase the pelvic capacity and potentially improve outcomes or might prompt a referral of the patient to a district hospital prior to the onset of labor.

The sonographic measurement of the ratio between the fetal head circumference and the obstetrical conjugate is accurate in predicting the risk of labor arrest: results from a multicenter prospective study

BACKGROUND

Labor arrest is estimated to account for approximately one-third of all primary cesarean deliveries, and is associated with an increased risk of adverse maternal and perinatal outcomes. One of the main causes is the mismatch between the size of the birth canal and that of the fetus, a condition usually referred to as cephalopelvic disproportion.

OBJECTIVE

This study aimed to describe a new ultrasound predictor of labor arrest leading to cesarean delivery because of suspected cephalopelvic disproportion.

STUDY DESIGN

This was a multicenter prospective study conducted at 3 maternity units from January 2021 to January 2022. A nonconsecutive series of singleton pregnancies with cephalic-presenting fetuses, gestational age of 34 weeks+0 days or above, and no contraindication to vaginal delivery attending at the antenatal clinics of each institution were considered eligible. Between 34+0 and 38+0 weeks of gestation, all eligible patients were submitted to transabdominal 2D ultrasound measurement of the obstetrical conjugate. On admission to the labor ward, the fetal head circumference was measured on the standard transthalamic plane by transabdominal ultrasound. The primary outcome of the study was the accuracy of the ratio between the fetal head circumference and the obstetrical conjugate measurement (ie, head circumference/obstetrical conjugate ratio) in predicting the occurrence of cesarean delivery secondary to labor arrest. The secondary outcome was the relationship between the head circumference/obstetrical conjugate ratio and labor duration.

RESULTS

A total of 263 women were included. Cesarean delivery for labor arrest was performed in 7.6% (20/263) of the included cases and was associated with more frequent use of epidural analgesia (95.0% vs 45.7%; P<.001), longer second stage of labor (193 [120-240] vs 34.0 [13.8-66.5] minutes; P=.002), shorter obstetrical conjugate (111 [108-114] vs 121 [116-125] mm; P<.001), higher head circumference/obstetrical conjugate ratio (3.2 [3.2-3.35] vs 2.9 [2.8-3.0]; P<.001), and higher birthweight (3678 [3501-3916] vs 3352 [3095-3680] g; P=.003) compared with vaginal delivery. At logistic regression analysis, the head circumference/obstetrical conjugate ratio expressed as Z-score was the only parameter independently associated with risk of cesarean delivery for labor arrest (odds ratio, 8.8; 95% confidence interval, 3.6-21.7) and had higher accuracy in predicting cesarean delivery compared with the accuracy of fetal head circumference and obstetrical conjugate alone, with an area under the curve of 0.91 (95% confidence interval, 81.7-99.5; P<.001). A positive correlation between the head circumference/obstetrical conjugate ratio and length of the second stage of labor was found (Pearson coefficient, 0.16; P=.018).

CONCLUSION

Our study, conducted on an unselected low-risk population, demonstrated that the head circumference/obstetrical conjugate ratio is a reliable antenatal predictor of labor arrest leading to 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.

Maternal postures for fetal malposition in labour for improving the health of mothers and their infants

BACKGROUND

Fetal malposition (occipito-posterior and persistent occipito-transverse) in labour is associated with adverse maternal and infant outcomes. Whether use of maternal postures can improve these outcomes is unclear. This Cochrane Review of maternal posture in labour is one of two new reviews replacing a 2007 review of maternal postures in pregnancy and labour.

OBJECTIVES

To assess the effect of specified maternal postures for women with fetal malposition in labour on maternal and infant morbidity compared to other postures.  SEARCH METHODS: We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (13 July 2021), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or cluster-RCTs conducted among labouring women with a fetal malposition confirmed by ultrasound or clinical examination, comparing a specified maternal posture with another posture. Quasi-RCTs and cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, risk of bias, and performed data extraction. We used mean difference (MD) for continuous variables, and risk ratios (RRs) for dichotomous variables, with 95% confidence intervals (CIs). We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included eight eligible studies with 1766 women.  All studies reported some form of random sequence generation but were at high risk of performance bias due to lack of blinding. There was a high risk of selection bias in one study, detection bias in two studies, attrition bias in two studies, and reporting bias in two studies. Hands and knees The use of hands and knees posture may have little to no effect on operative birth (average RR 1.14, 95% CI 0.87 to 1.50; 3 trials, 721 women; low-certainty evidence) and caesarean section (RR 1.34, 95% CI 0.96 to 1.87; 3 trials, 721 women; low-certainty evidence) but the evidence is uncertain; and very uncertain for epidural use (average RR 0.74, 95% CI 0.41 to 1.31; 2 trials, 282 women; very low-certainty evidence), instrumental vaginal birth (average RR 1.04, 95% CI 0.57 to 1.90; 3 trials, 721 women; very low-certainty evidence), severe perineal tears (average RR 0.88, 95% CI 0.03 to 22.30; 2 trials, 586 women; very low-certainty evidence), maternal satisfaction (average RR 1.02, 95% CI 0.68 to 1.54; 3 trials, 350 women; very low-certainty evidence), and Apgar scores less than seven at five minutes (RR 0.71, 95% CI 0.21 to 2.34; 2 trials, 586 babies; very low-certainty evidence).  No data were reported for the hands and knees comparisons for postpartum haemorrhage, serious neonatal morbidity, death (stillbirth or death of liveborn infant), admission to neonatal intensive care, neonatal encephalopathy, need for respiratory support, and neonatal jaundice requiring phototherapy.  Lateral postures The use of lateral postures may have little to no effect on reducing operative birth (average RR 0.72, 95% CI 0.43 to 1.19; 4 trials, 871 women; low-certainty evidence), caesarean section (average RR 0.78, 95% CI 0.44 to 1.39; 4 trials, 871 women; low-certainty evidence), instrumental vaginal birth (average RR 0.73, 95% CI 0.39 to 1.36; 4 trials, 871 women; low-certainty evidence), and maternal satisfaction (RR 0.96, 95% CI 0.84 to 1.09; 2 trials, 451 women; low-certainty evidence), but the evidence is uncertain. The evidence is very uncertain about the effect of lateral postures on severe perineal tears (RR 0.66, 95% CI 0.17 to 2.48; 3 trials, 609 women; very low-certainty evidence), postpartum haemorrhage (RR 0.90, 95% CI 0.48 to 1.70; 1 trial, 322 women; very low-certainty evidence), serious neonatal morbidity (RR 1.41, 95% CI 0.64 to 3.12; 3 trials, 752 babies; very low-certainty evidence), Apgar scores less than seven at five minutes (RR 0.25, 95% CI 0.03 to 2.24; 1 trial, 322 babies; very low-certainty evidence), admissions to neonatal intensive care (RR 1.41, 95% CI 0.64 to 3.12; 2 trials, 542 babies; very low-certainty evidence) and neonatal death (stillbirth or death of liveborn) (1 trial, 210 women and their babies; no events).  For the lateral posture comparisons, no data were reported for epidural use, neonatal encephalopathy, need for respiratory support, and neonatal jaundice requiring phototherapy. We were not able to estimate the outcome death (stillbirth or death of liveborn infant) due to no events (1 trial, 210 participants).  AUTHORS' CONCLUSIONS: We found low- and very low-certainty evidence which indicated that the use of hands and knees posture or lateral postures in women in labour with a fetal malposition may have little or no effect on health outcomes of the mother or her infant. If a woman finds the use of hands and knees or lateral postures in labour comfortable there is no reason why they should not choose to use them. Further research is needed on the use of hands and knees and lateral postures for women with a malposition in labour. Trials should include further assessment of semi-prone postures, same-side-as-fetus lateral postures with or without hip hyperflexion, or both, and consider interventions of longer duration or that involve the early second stage of labour.

Sonographic risk assessment for an unplanned operative delivery: a prospective study

PURPOSE

To assess the value of pre-labor maternal and fetal sonographic variables to predict an unplanned operative delivery.

METHODS

In this prospective study, nulliparous women were recruited at 37.0-42.0 weeks of gestation. Sonographic measurements included estimated fetal weight, maternal pubic arch angle, and the angle of progression. We performed a descriptive and comparative analysis between two outcome groups: spontaneous vaginal delivery (SVD) and unplanned operative delivery (UOD) (vacuum-assisted, forceps-assisted and cesarean deliveries). Multivariate logistic regression with ROC analysis was used to create discriminatory models for UOD.

RESULTS

Among 234 patients in the study group, 175 had a spontaneous vaginal delivery and 59 an unplanned operative delivery. Maternal height and pubic arch angle (PAA) significantly correlated with UOD. Analysis of Maximum Likelihood Estimates revealed a multivariate model for the prediction of UOD, including the parameters of maternal age, maternal height, sonographic PAA, angle of progression (AOP), and estimated fetal weight, with an area under the curve of 0.7118.

CONCLUSION

Sonographic parameters representing maternal pelvic configuration (PAA) and maternal-fetal interface (AOP) improve the prediction ability of pre-labor models for a UOD. These data may aid the obstetrician in the counseling process before delivery.

Antepartum ultrasound prediction of failed vacuum-assisted operative delivery: a prospective cohort study

BACKGROUND

Failed vacuum-assisted delivery (VD) is associated with increased risk of maternal perineal trauma and neonatal morbidity. Knowledge of the risk factors related to failed VD is essential in the clinical decision-making.

OBJECTIVE

To elucidate the strength of association and the predictive accuracy of different ante-partum ultrasound parameters in predicting the risk of failed VD prior to the onset of Labor and to test the diagnostic performance of a multiparametric model including pregnancy and Labor characteristics, ante and intra-partum ultrasound in anticipating failed VD.

STUDY DESIGN

Prospective study of consecutive singleton pregnancies complicated by VD undergoing a dedicated ultrasound assessment at 36-38 weeks of gestation. Head circumference (HC), estimated fetal weight (EFW) and subpubic angle and (SPA) were recorded before the onset of Labor. At the time of the VD, occiput position, head perineum distance (HPD) and angle of progression (AOP) were also recorded. Multivariate logistic regression and area under the curve (AUC) analyses were used to explore the strength of association and test the diagnostic accuracy of different maternal, Labor and ultrasound characteristics in predicting g failed VD.

RESULTS

Four hundred eight pregnancies with successful and 26 with failed VD were included in the analysis. Fetuses experiencing failed VD had a larger HC (1.21 versus 1.07 MoM; p = .0001), a higher EFW z-value (0.56 versus 0.33 z values; p = .002) and a narrower SPA (114 versus 122 p = .0001) compared to those having a successful VD. At multivariable logistic regression analysis, maternal height (aOR 0.89 95% CI 0.76-0.98), nulliparity (aOR: 1.14 95% CI 1.06-1.36), HC MoM (aOR: 1.24 95% CI 1.13-1.55) and SPA angle (aOR: 0.82 95% CI 0.67-0.95), but not EFW (p = .08) were independently associated with failed VD. When intrapartum ultrasound variables were added to the multivariate model, fetal occipital position (aOR: 1.45 95th CI 1.11-1.99) and HPD (aOR: 0.77 95th CI 0.44-0.96) were independently associated with failed VD. A multiparametric model integrating pregnancy and Labor characteristics and ante-partum ultrasound variables had an AUC of 0.837 (95% CI 0.797-0.876) for the prediction of failed VE. The addition of intra-partum ultrasound variables to the prediction model, improved the accuracy for failed VD provided by maternal and antepartum ultrasound characteristics with an AUC of 0.913 (0.888-0.937).

CONCLUSION

Antepartum prediction of failed VD is feasible. HC, SPA but not EFW are independently associated and predictive of failed VD. Adding these variables to a multiparametric model including maternal and intrapartum ultrasound parameters improves the diagnostic accuracy for failed VD.

Antepartum evaluation of the obstetric conjugate at transabdominal 2D ultrasound: A feasibility study

INTRODUCTION

The obstetric conjugate represents the shortest anteroposterior diameter of the birth canal and it reflects the capacity of the pelvic inlet to allow the passage and the engagement of the fetal head. The antepartum evaluation of this parameter may be attempted at digital examination to predict the risk of cephalopelvic disproportion, but the accuracy of clinical pelvimetry is notoriously poor. The aim of our study was to describe the sonographic measurement of the obstetric conjugate at transabdominal 2D-ultrasound and to assess its reproducibility.

MATERIAL AND METHODS

This is a prospective cohort study conducted at a tertiary University hospital. A non-consecutive series of pregnant women with uncomplicated singleton pregnancies attending the antenatal clinic for routine booking from 34 weeks of gestation onward were included. The ultrasound probe was longitudinally placed above the level of the symphysis and the interpubic fibrocartilaginous disk was visualized. Then the promontory was identified as the most prominent segment of the sacral vertebral column. The obstetric conjugate was measured as the distance between the inner edge of the interpubic disk and the promontory. The inter- and intraobserver repeatability of this measurement was calculated using the intraclass correlation coefficient (ICC) and the Bland-Altman method.

RESULTS

In all, 119 women were considered eligible for the study; of these, 111/119 (93.3%) women were included in the analysis with a median gestational age of 36.0 (35.0-37.0) weeks. The mean obstetric conjugate measurement was 11.4 ± 0.93 mm for the first operator and 11.4 ± 0.91 mm for the second operator. The overall interobserver ICC was 0.95 (95% [confidence interval] CI 0.92-0.96) and the overall intraobserver ICC was 0.97 (95% CI 0.96-0.98). Limits of agreement ranged from -0.84 to 0.80 for interobserver measures and from -0.64 to 0.62 for intraobserver measures. The degree of reliability was also analyzed for women with a body mass index ≥30 and for women with a gestational age ≥37 weeks. The inter- and intraobserver ICCs were respectively 0.97 (95% CI 0.90-0.98) and 0.98 (0.95-0.99) in the former group and 0.96 (95% CI 0.93-0.98) and 0.97 (95% CI 0.95-0.98) in the latter group.

CONCLUSIONS

Our study demonstrated that among pregnant women at term gestation, sonographic measurement of the obstetric conjugate is feasible and reproducible.

The usefulness of ultrasound before induction of labor

The indications for induction of labor have been consistently on the rise. These indications are mainly medical (maternal or fetal) or social or related to convenience or maternal preferences. With the increase in the prevalence of these indications, the incidence rates of induction of labor are expected to rise continuously. This poses a substantial workload and financial burden on maternity healthcare systems. Failure rates of induction of labor are relatively high, especially when considering the maternal, fetal, and neonatal risks associated with emergency cesarean deliveries in cases of failure. Therefore, it is essential for obstetricians to carefully select women who are eligible for induction of labor, particularly those with no clinical contraindication and who have a reasonable chance of ending up with a successful noncomplicated vaginal delivery. Ultrasound has an established role in the various areas of obstetrical care. It is available, accessible, easy to perform, and acceptable to the patient. In addition, the learning curve for skillful obstetrical ultrasound scanning is rather easy to fulfill. Ultrasound has always had an important role in the assessment of maternal and fetal well-being. Indeed, it has been extensively explored as a reliable, reproducible, and objective tool in the management of labor. In this review, we aimed to provide a comprehensive update on the different applications and uses of ultrasound before induction of labor for the prediction of its success and the potential improvement of its health-related maternal and fetal outcomes.

Association of term isolated microcephaly with mode of delivery and perinatal outcome - a retrospective case-control analysis

Background

We aimed to evaluate the association of isolated fetal microcephaly measured by ultrasound prior to delivery at term with mode of delivery and perinatal outcome.

Methods

A single-center retrospective study was conducted in 2012–2016. Fetal microcephaly was defined as head circumference > 2 standard deviations of the mean for gestational age and sex. We compared the obstetric, delivery, and outcome parameters of women in whom ultrasound performed up to 10 days prior to term delivery showed isolated fetal microcephaly (study group) or normal head circumference (reference group). Exclusion criteria were intrauterine fetal death, birthweight below the 10th percentile, and antepartum cesarean delivery for any indication.

Results

Of 3677 women included in the study, 26 (0.7%) had a late ultrasound finding of isolated fetal microcephaly. Baseline characteristics were similar in the two groups except for estimated fetal weight based on abdominal circumference and biparietal diameter, which was lower in the microcephaly group (3209.8 ± 557.6 vs. 2685.8 ± 420.8 g, p < .001). There was no significant between-group difference in rate of vaginal operative deliveries (11.7% vs 14.8%, respectively, p = 0.372). The study group had no intrapartum cesarean deliveries compared to 6.3% of the reference group (NS). Compared to controls, neonates in the study group were smaller (3323.2 ± 432.2 vs. 2957.0 ± 330.4 g, p < .001), with lower birthweight percentile (60.5 ± 26.5 vs. 33.6 ± 21.5%, p < .001) and were more often males (48.2 vs. 90.0%, p < .001). No significant differences were noted in perinatal outcomes between the groups, including admission to neonatal intensive care unit, intraventricular hemorrhage, 5-min Apgar score < 7, asphyxia, seizures, and sepsis.

Conclusions

Isolated microcephaly in term fetuses is not advantageous for a vaginal delivery, nor does it does not pose a greater than normal risk of adverse perinatal outcome.

Role of ante-partum ultrasound in predicting vaginal birth after cesarean section: A prospective cohort study

INTRODUCTION

Vaginal birth after caesarean delivery is associated with better outcomes compared to repeat caesarean section. Accurate antenatal risk stratification of women undergoing a trial of labor after caesarean section is crucial in order to maximize perinatal and maternal outcomes. The primary aim of this study was to explore the role of antepartum ultrasound in predicting the probability of vaginal birth in women attempting trial of labor; the secondary aim was to build a multiparametric prediction model including pregnancy and ultrasound characteristics able to predict vaginal birth and compare its diagnostic performance with previously developed models based exclusively upon clinical and pregnancy characteristics.

METHODS

Prospective study of consecutive singleton pregnancies scheduled for trial of labor undergoing a dedicated antepartum ultrasound assessment at 36-38 weeks of gestation. Head circumference, estimated fetal weight cervical length, sub-pubic angle were recorded before the onset of labour. The obstetricians and midwives attending the delivery suite were blinded to the ultrasound findings. Multivariate logistic regression and area under the curve analyses were used to explore the strength of association and test the diagnostic accuracy of different maternal and ultrasound characteristics in predicting vaginal birth. Comparison with previously reported clinical models developed by the Maternal-Fetal Medicine Unit Network (Grobman's models) was performed using De Long analysis.

RESULTS

A total of 161women who underwent trial of labor were included in the study. Among them 114 (70.8 %) women had successful vaginal birth. At multivariable logistic regression analysis maternal height (adjusted odds ratio (aOR):1.24;9 5% Confidence Interval (CI)1.17-1.33), previous C-section for arrest labor (aOR:0.77; 95 %CI0.66-0.93), cervical dilation at admission (aOR:1.35 ; 95 %CI1.12-1.74), fetal head circumference (aOR:0.77 ; 5%CI0.43-0.89), subpubic angle (aOR:1.39 95 %CI1.11-1.99) and cervical length (aOR:0.82 95 % CI0.54-0.98) were independently associated with VBAC. A model integrating these variables had an area under curve of 0.839(95 % CI 0.710-0.727) for the prediction of vaginal birth, significantly higher than those achieved with intake (0.694; 95 %CI0.549-0.815; p = 0.01) and admission (0.732: 95 % CI 0.590-0.84; p = 0.04) models reported by Grobman.

CONCLUSION

Antepartum prediction of vaginal birth after a caesarean section is feasible. Fetal head circumference, subpubic angle and cervical length are independently associated and predictive of vaginal birth. Adding these variables to a multiparametric model including maternal parameters improves the diagnostic accuracy of vaginal birth compared to those based only on maternal characteristic.

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.

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.

Fetal head circumference and subpubic angle are independent risk factors for unplanned cesarean and operative delivery

INTRODUCTION

The aim of this study was to ascertain whether combined ultrasound assessment of fetal head circumference (HC) and maternal subpubic angle (SPA) prior to the onset of labor may predict the likelihood of an unplanned operative delivery (UOD) in nulliparous women at term.

MATERIAL AND METHODS

Prospective cohort study of singleton pregnancies in cephalic presentation. Pregnancies experiencing UOD secondary to fetal distress were excluded. HC was assessed transabdominally and SPA values were obtained from a reconstructed coronal plane on three-dimensional (3D) ultrasound performed translabially at 36-38 weeks of gestation. Maternal characteristics, HC expressed as multiple of median, and SPA were compared according to the mode of delivery. Logistic regression and receiver operating characteristics curve analyses were used to analyze the data.

RESULTS

597 pregnancies were included in the study. Spontaneous vaginal delivery occurred in 70.2% of the cases and UOD was required in 29.8%. There was no difference in pregnancy characteristics and birthweight between women who had a spontaneous vaginal birth compared with UOD. The HC multiple of median was larger (1.00 ± 0.02 vs. 1.03 ± 0.02, p ≤ 0.0001), whereas SPA was narrower in the UOD group (124.02 ± 13.64 vs. 102.61 ± 16.13, p ≤ 0.0001). At logistic regression, SPA (OR 0.91, 95% CI 0.89-0.93), HC multiple of median (OR 1.13, 95% CI 1.09-1.17) and maternal height (OR 0.95, 95% CI 0.92-0.99) were independently associated with UOD. When combined, the diagnostic accuracy of a predictive model integrating HC, SPA and maternal height was highly predictive of UOD with an area under the curve of 0.904 (95% CI 0.88-0.93).

CONCLUSIONS

Ultrasound assessment of fetal HC and maternal SPA after 36 weeks of gestation can identify a subset of women at higher risk of UOD during labor, for whom early planned delivery might be beneficial.

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.

Agreement between two 3D ultrasound techniques for the assessment of the subpubic arch angle

OBJECTIVES

To assess the reliability of a new three-dimensional (3D) ultrasound technique for the measurement of the subpubic arch angle (SPA) and the agreement between two contrast-enhancing 3D ultrasound techniques.

METHODS

We acquired two static 3D transperineal volumes from 72 nulliparous women using two ultrasound machines equipped with two different 3D contrast enhancement and linear reconstruction softwares: 1. Oblique View Extended Imaging with HD-Volume Imaging (OVIX-HDVI™), Samsung; 2. Omniview with Volume Contrast Imaging (Omniview-VCI™), GE Healthcare. An operator measured SPA once by OVIX-HDVI, and twice by Omniview-VCI, while another operator measured SPA once by Omniview-VCI. We evaluated intra- and inter-observer reproducibility of Omniview-VCI and intermethod agreement. Reproducibility and intermethod agreement were studied by means of intraclass correlation coefficient (ICC) and Bland-Altman method.

RESULTS

Omniview-VCI SPA measurements showed excellent intraobserver and interobserver reproducibility (ICC 0.970; 95% C.I. 0.952 to 0.981, 0.932; 95% C.I. 0.893 to 0.957, respectively). Furthermore, Omniview VCI SPA measurements demonstrated excellent agreement with those performed by OVIX-HDVI technique (ICC 0.943; 95 C.I. 0.911 to 0.964). No systematic difference was found in any of the reliability studies.

CONCLUSIONS

OmniView-VCI is a reliable method for SPA assessment. Both OmniView-VCI and OVIX-HDVI can be used interchangeably for SPA measurement.

Is intrapartum translabial ultrasound examination painless?

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Subpubic Arch Angle and Mode of Delivery in Low-Risk Nulliparous Women

Objective: To assess whether subpubic arch angle (SPA) measurement before labor onset can predict labor outcome among low-risk pregnant women. Methods: 3D ultrasound volume was transperineally acquired from a series of nulliparous women with uncomplicated pregnancy at term before the onset of labor. SPA was measured offline using Oblique View Extended Imaging (OVIX) on each volume performed by an investigator not involved in the clinical management. Labor outcome was prospectively investigated in the whole study group. Results: Overall, 145 women were enrolled in the study. Of these, 83 underwent spontaneous vaginal delivery, whereas obstetric intervention was performed in 62 cases (Cesarean section in 40 and vacuum extraction in 22). The SPA appeared to be significantly narrower in the women submitted to obstetric intervention compared with those undergoing spontaneous vaginal delivery (116.8 ± 10.3° vs. 123.7 ± 9.6°, p < 0.01). At multivariate analysis SPA and maternal age were identified as independent predictors of the mode of delivery. On the other hand, the duration of labor did not show a significant relationship with SPA. Conclusions: In low-risk nulliparous women at term gestation, SPA measurement obtained by 3D ultrasound before the onset of labor seems to predict the likelihood of an obstetric intervention but not the duration of labor.

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.

Measurement of subpubic arch angle by three-dimensional transperineal ultrasound and impact on vaginal delivery

OBJECTIVES

To assess whether antepartum measurement of the subpubic arch angle (SPAA) as a parameter of the bony pelvic outlet can predict vaginal delivery.

METHODS

Between January 2007 and June 2011, 625 nulliparous women with a singleton pregnancy were recruited from the antenatal clinic to be interviewed and have a four-dimensional transperineal ultrasound examination. Ultrasound examinations were performed between 34 and 36 weeks of gestation. Volume ultrasound data were saved for offline analysis, blinded against all other data. The SPAA was measured in the axial plane and logistic regression analysis was used to examine the association between SPAA and outcomes of vaginal delivery vs Cesarean section in the second stage of labor, and normal vs assisted vaginal delivery. The association between SPAA and the duration of second stage of labor was also analyzed.

RESULTS

Of the 625 women recruited initially, 14 ultrasound data files could not be retrieved, providing a total of 611 ultrasound images for measurement of SPAA. Complete obstetric and ultrasound data were obtained from 593 patients. Mean SPAA was 109.3° (range, 65.6-131.6°). There was no association between SPAA and the odds of a vaginal delivery (odds ratio, 1.01 (95% CI, 0.97-1.06)). However, there was evidence of an association between SPAA and duration of second stage of labor within the subgroup of women with a normal vaginal delivery (cause-specific hazard ratio, 1.02 (95% CI, 1.01-1.03); P = 0.003).

CONCLUSIONS

SPAA is not useful for predicting vaginal delivery; however, there is an association between this parameter and the duration of the second stage of labor.

Intrapartum sonography - eccentricity or necessity?

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

A New Method to Measure the Subpubic Arch Angle Using 3-D Ultrasound

Objectives: The aim of this study was to assess the reproducibility of both a new contrast-enhancing technique (Oblique View eXtended Imaging, OVIX; Samsung) and the recently reported 3-D multiplanar technique (MPT) in the measurement of the subpubic angle (SPA) among a group of women at term gestation. In addition, we aimed to study the intermethod agreement between the OVIX technique and MPT. Methods: We acquired a transperineal 3-D ultrasound volume from 155 women with a singleton uncomplicated term pregnancy before the onset of labor. Each 3-D dataset was analyzed by the MPT and OVIX algorithm. The angle formed by the lower edges of the pubic rami (SPA) was measured twice by an operator and once by another operator for each technique in order to assess intra- and interobserver reproducibility. Reproducibility and intermethod agreement were studied by means of the intraclass correlation coefficient (ICC) and Bland-Altman method. Results: SPA measurements performed with OVIX showed high intraobserver [ICC 0.912, 95% confidence interval (CI) 0.882-0.935] and good interobserver (ICC 0.791, 95% CI 0.724-0.844) agreement, while those measured with MPT showed moderate intraobserver (ICC 0.573, 95% CI 0.457-0.670) and good interobserver (ICC 0.640, 95% CI 0.537-0.724) agreement. Whereas the intermethod analysis showed good agreement between the MPT and the OVIX techniques (ICC 0.614, 95% CI 0.414-0.757), the SPA measured by MPT were significantly wider than those measured by OVIX (125 ± 12 vs. 120 ± 11°, p = 0.006). Conclusions: OVIX is a reliable technique for SPA measurement. MPT overestimates the SPA in comparison with OVIX. Further studies are needed to assess its clinical utility.

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.

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.

Head progression distance in prolonged second stage of labor: relationship with mode of delivery and fetal head station

OBJECTIVE

To evaluate the clinical significance of fetal head progression distance (HPD), measured by transperineal ultrasound, during prolonged second stage of labor.

METHODS

In this prospective study, a single operator, who was blinded to the results of the digital examination, assessed using transperineal ultrasound women at ≥ 37 weeks of gestation with failure to progress in the second stage of labor. Patients had an empty urinary bladder and the examination was performed during maternal pushing. HPD was defined as the length of the line perpendicular to the infrapubic line that would connect it to the lowest part of the fetal bony skull. We analyzed associations between HPD and digital examination of fetal head station, fetomaternal characteristics, mode of delivery and perinatal outcome.

RESULTS

Sixty-five patients in prolonged second stage of labor participated in the study. The overall mean HPD was 6.50 (± 1.35; 95% CI, 6.16-6.83) cm. No correlation was found between HPD and head position or mode of delivery, but HPD was positively correlated with fetal head station and neonatal head circumference measured after delivery. Logistic regression and receiver-operating characteristics curve analysis demonstrated no significant predictive value of HPD with respect to mode of delivery.

CONCLUSION

Although HPD in prolonged second stage of labor could not predict mode of delivery, it may have a role as an ancillary tool for fetal head station assessment.