Fetal Head Station Research Articles

Intrapartum ultrasound during rotational forceps delivery: a novel tool for safety, quality control, and teaching

Operative vaginal delivery and, in particular, rotational forceps delivery require extensive training, specific skills, and dexterity. Performed correctly, it can reduce the need for difficult late second-stage cesarean delivery and its associated complications. When rotation to occiput anterior position is achieved, pelvic trauma and anal sphincter injury commonly associated with direct delivery from occiput posterior positions may be avoided. We report the original and novel use of real-time intrapartum ultrasound simultaneously during Kielland's rotational forceps delivery to monitor correct execution and increase maternal safety. This is a prospective observational study performed at the Charité University Hospital in Berlin between 2013 and 2018. Simultaneous, real-time, intrapartum suprapubic ultrasound during Kielland's rotational forceps deliveries were performed in a series of laboring women with normal fetuses and arrest of labor in the late second stage and with a fetal head malposition, requiring operative vaginal delivery. In addition to vaginal palpation for head station, rotation, and asynclitism, intrapartum ultrasound was also used to objectively determine head station, head direction, and midline angle. The operator was not blinded to the ultrasound findings. The delivering obstetrician examined the woman and performed the delivery. An assistant, trained in intrapartum ultrasound, placed a curved-array transducer transversely in the midline just above the pubic bone to display the forceps blades being applied and the rotation of the fetal head in occiput anterior position. In all 32 laboring women included in the study, the blades were applied correctly and the fetal heads successfully rotated to an occiput anterior position with direct ultrasound confirmation, and vaginal delivery was achieved. There were no cases of difficult application, repeat application, slippage of the blades, or rotation of the fetal head in the wrong direction. Maternal outcomes showed no vaginal tears, cervical tears, or postpartum hemorrhage >500 mL. There was 1 case of third-degree perineal tear (3a). Neonatal outcomes included mild hyperbilirubinemia (n=1), small cephalohematoma conservatively managed (n=1), and early-onset group B streptococcus sepsis secondary to maternal colonization (n=1). There were no neonatal deaths. Ultrasound guidance during Kielland's rotational forceps delivery is an original and novel approach. We describe the use of intrapartum ultrasound in assessing fetal head station and position and also to simultaneously and objectively monitor performance of rotational forceps delivery. Intrapartum ultrasound enhances operator confidence and, possibly, patient safety. It is a valuable adjunct to obstetrical training and can improve learning efficiency. Real-time ultrasound guidance of fetal head rotation to occiput anterior position with Kielland's forceps may also protect the perineum and reduce anal sphincter injury. This novel approach can lead to a renaissance in the safe use of Kielland's forceps.

Feasibility, Reliability, and Agreement of Transperineal Ultrasound Measurement: Results from a Longitudinal Cohort Study

Objectives: To evaluate the feasibility, reliability, and agreement of serial transperineal ultrasound (TPU) assessment of fetal head station (parasagittal angle of progression [psAOP], head-perineum distance [HPD], and head-symphysis distance [HSD]) and sonographic cervical dilatation (SCD), compared to fetal head station and cervical dilatation determined by vaginal examination, respectively. Methods: This was a prospective longitudinal study in singleton pregnancies undergoing induction of labor at term. Paired assessment of fetal head station and cervical dilatation by vaginal examination, with TPU assessment of psAOP, HPD, HSD, and SCD was made serially. Feasibility, correlation, reliability, and agreement were determined. Results: 1,139 paired measurements among 326 women were included. psAOP and HPD were achievable in all assessments. HSD was not achievable in 3.4% (11/326) due to high fetal head station. Fetal head station by vaginal examination was positively correlated with psAOP (rho = 0.70) but negatively correlated with HPD (rho = −0.57) and HSD (rho = −0.52). The feasibility to measure SCD reduced as cervical dilatation increased. Cervical dilatation and SCD were positively correlated (rho = 0.96) with strong agreement (concordant correlation coefficient = 0.925). Conclusions: Measurements of psAOP and HPD are feasible and correlate significantly with fetal head station by vaginal examination. Measurement of HSD is not feasible when fetal head station is high. Measurement of SCD is feasible, but it is more difficult in the advanced stage of labor. The correlation, reliability, and agreement between SCD and cervical dilatation by vaginal examination are high.

A Novel Partogram for Stages 1 and 2 of Labor Based on Fetal Head Station Measured by Ultrasound: A Prospective Multicenter Cohort Study.

This study was aimed to describe continuous labor curves, including second stage, based on fetal head station. We performed a prospective multicenter cohort study. The inclusion criteria were women with singleton uncomplicated cephalic term pregnancies in labor, who delivered vaginally. We used a device that combines ultrasound imaging with position-tracking technology to monitor the head station noninvasively throughout labor. We collected data on demographics, labor parameters, and delivery and neonatal outcomes. A total of 613 women delivered vaginally, 327 (53.3%) were nulliparous, while 286 (46.7%) were multiparous. Time to delivery (TTD) diminished progressively with descent of the fetal head. When the head is engaged, the labor curve of multiparous women demonstrated a more prominent downward shift in curve as compared with nulliparous women. When comparing multipara and nullipara at engagement level, the median TTD was 1 and 1.62 hours, respectively. In 95% of women with unengaged head during the second stage, TTD of nulliparous and multiparous women were less than 3.8 and 3 hours, respectively. While current labor curves end at full dilatation, the described curves were developed throughout stages 1 and 2 of labor. The TTD, according to the station curves, shows an acceleration of labor, once passed the engagement level, especially in multiparous women.

Malmström vacuum or Kielland forceps: which causes more damage to pelvic floor?

To determine whether differences exist in the rate of levator ani muscle (LAM) avulsion between women who had undergone either Malmström vacuum delivery (MVD) or Kielland forceps delivery (KFD), allowing for potential confounding factors. This was a prospective observational study of nulliparous women undergoing instrumental delivery using Malmström vacuum extractor or Kielland forceps, at two hospital centers in Spain. Fetal head position (anterior, posterior or transverse) and fetal head station (low or mid) were assessed by ultrasound and digital examination, respectively. Avulsion was defined on tomographic ultrasound imaging as an abnormal insertion of the LAM in the three central slices from the plane of minimal hiatal dimensions. In total, 414 patients were included in the study (212 MVD and 202 KFD). We observed a higher rate of LAM avulsion in the KFD group (KFD 49.5% vs MVD 32.5%; P = 0.001). When the results were evaluated according to fetal head position and station, we observed no differences in LAM avulsion. The crude odds ratio (OR) for the difference in avulsion between women in the KFD and MVD groups was 2.03 (95% CI, 1.36-3.03). However, when adjusted for duration of second stage of labor, fetal head circumference and fetal head station, the OR was no longer statistically significant (OR, 2.14 (95% CI, 0.95-4.85); P = 0.068). When potential confounding factors are taken into account, the rate of LAM avulsion does not differ between women according to whether they have undergone KFD or MVD. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

806: The impact of the fetal head station on the second stage of labor

806: The impact of the fetal head station on the second stage of labor

Station of the fetal head at complete cervical dilation impacts duration of second stage of labor.

ObjectiveTo examine the association between station of the fetal head at complete cervical dilation and duration of second stage of labor, as well as prolonged second stage of labor, without and with the use of analgesia (EA).Study designWe conducted a population-based retrospective cohort study of 3311 women with a singleton pregnancy, gestational age ≥ 370 weeks, and cephalic presentation. Station of the fetal head at complete cervical dilation was categorized as at the pelvic floor, beneath the ischial spines, but above the pelvic floor, and at or above the ischial spines. In logistic regression analysis, we defined prolonged second stage of labor as > 2 h without and > 3 h with EA in nulliparous women, and > 1 h and > 2 h, respectively, in parous women.ResultsSurvival curves demonstrated longer durations of second stage of labor in nulliparous women and women with EA in each category of station of fetal head. The adjusted odds ratio of prolonged second stage of labor was 13.1 (95% confidence interval (CI): 8.5-20.1) times higher when the fetal head was beneath the ischial spines, but above the pelvic floor, and 32.9 (95% CI: 21.5-50.2) times higher when the fetal head was at or above the ischial spines compared to at the pelvic floor.ConclusionStation of the fetal head at complete cervical dilation was significantly associated with duration of second stage of labor.

Preferred way of delivery of the impacted fetal head in cesarean sections during second stage of labor.

To compare maternal and neonatal outcomes between the 'head first' and 'legs first' delivery methods during a second stage cesarean section. We conducted a retrospective study between January 2009 and May 2015 at a large public university tertiary referral center. Included were all women who underwent cesarean delivery with a fully dilated cervix and a fetal head at the level of the ischial spines or below. The study population was divided into two groups according to way of fetal delivery: The 'legs first' (reverse breech) method and the 'head first' method. Demographics and maternal and fetal outcomes were retrieved for both groups. During the study period 447 women underwent a cesarean section while their cervix was fully dilated. Of them, 321 met the inclusion criteria: One hundred and twenty-one (38%) were delivered using the 'legs first' method and 200 (62%) were delivered using the 'head first' method. Indication for surgery and fetal head station was similar for both groups. While no difference in overall intraoperative uterine incision extension rate was observed, a higher rate of uterine incision extension was demonstrated in the 'head first' group in cases in which the second stage was longer than 180 min (33 vs 8 cases, P = 0.02). No differences in maternal postoperative complication rates and neonatal outcomes were observed. Fetal extraction via the 'legs first' method during prolonged second stage of labor may lower maternal morbidity. Method of delivery does not seem to have an effect on neonatal outcomes.

Structured clinical examinations in labor: rekindling the craft of obstetrics

Objectives Exact knowledge of fetal station and position is of paramount importance for reliable surveillance of labor progress and a prerequisite for safe operative vaginal procedures. Detailed clinical assessments are thoroughly described in old textbooks, but almost forgotten in contemporary obstetrics. Ultrasound is suggested as an objective diagnostic tool in active labor. Several publications have demonstrated a low correlation between ultrasound and clinical assessment of fetal head station and position, but the methods of clinical assessment in these studies are poorly described. We wanted to explore if a quality clinical assessment could perform better than clinical assessment in previous publications, by analyzing the correlation between a structured method of clinical assessment and intrapartum ultrasound. Methods In all, 100 laboring women with cervical dilatation ≥7 cm were included in a prospective cohort study at Oslo University Hospital-Ullevål from October to December 2016. The study design was cross-sectional. Clinical examinations were performed by one special educated consultant (JKI), and transabdominal and transperineal ultrasound clips were recorded and examined by a blinded expert in intrapartum ultrasound (TME). Fetal position was classified as a clock face with 12 units (hourly divisions) and thereafter categorized as occiput anterior (OA), left occiput transverse (LOT), occiput posterior (OP), and right occiput transverse (ROT) positions. Fetal station was categorized clinically from −5 to +5 and measured with ultrasound as angle of progression (AoP) and head-perineum distance (HPD). AoP is the angle between a longitudinal line through the symphysis and a tangent to the head contour. HPD is the shortest distance between the fetal skull and the perineum. Results Eight women were excluded due to strong contractions between clinical assessments and ultrasound measurements, fetal distress, or incomplete examinations. Fetal position assessed with ultrasound and clinical examination agreed exactly in 48/92 (52%) of cases, within one unit (hour) in 87/92 (95%) of cases and within two units in 90/92 (98%) of cases. It differed by three units in one case and by five units in one case. The agreement categorized into OA, LOT, OP, and ROT was good (Cohen’s kappa 0.72; 95% CI 0.61–0.84). For station, the agreement was very good for both HPD (Pearson correlation coefficient r = 0.86; 95% CI 0.80–0.91) and AoP (r = 0.77; 95% CI to 0.67–0.84). The correlation between HPD and AoP was good (r = 0.76; 95% CI 0.65–0.84). Conclusion We found very good correlations between structured clinical assessments and ultrasound examinations, suggesting that an objective quality in clinical examinations is possible to achieve. More focus on clinical skills training may improve accuracy for clinicians.

Operative vacuum vaginal delivery: effect of compliance with recommended checklist

Purpose Even if the prerequisites and the technique of vacuum extraction are largely established, the role of a checklist in this field has not been tested. To evaluate the role of a checklist implementation on the compliance with the recommended rules in operative vacuum vaginal delivery (OVD) and on maternal and perinatal outcomes. Materials and methods Retrospective cohort study on OVD between January 2012 and December 2015 at two hospitals with a tradition of teaching of OVD. A checklist for OVD was introduced in 2014. Three rules had to be recorded: fetal head station and position determination, no more than four tractions, and no more than three cup applications. Adverse maternal outcomes included third- and fourth-degree perineal tears. Adverse neonatal outcome included asphyxia, need for neonatal resuscitation, NICU admission, major head injuries, scalp injuries, and bone or brachial plexus injuries. Results Introduction of a checklist for OVD resulted in an increase in the compliance with the rules (83.3 versus 62.8%, p < .001). Cases in which the rules were respected had lower incidence of third- and fourth-degree perineal lacerations after controlling for episiotomy, nulliparity, and indication for OVD (OR = 0.4, 95% CI 0.18–0.89), but similar rates of failure of OVD (2.1 versus 2.2%, p = 1) and adverse neonatal outcome (10.8 versus 11.7%, p=.71). Conclusion Knowledge and documented compliance with a checklist of recommended rules in OVD may assist in achieving a lower rate of severe perineal and anal sphincter injury but does not alter the success of the procedure or neonatal outcome.

Assessment of labor progression by intrapartum ultrasonography among term nulliparous women.

To assess cervical dilation, fetal head station, and fetal head position by intrapartum ultrasonography and to compare the approach with digital vaginal examination (DVE). An observational study conducted from October 2015 to January 2017 among term nulliparous women in active labor at a tertiary hospital in Delhi, India. Cervical dilation, head station, and head position were assessed by DVE, followed by ultrasonography within 10minutes. The women's preference was also evaluated. Overall, 458 observations were obtained for 215 women. Cervical dilation measured by DVE was strongly correlated with ultrasonography findings (intraclass correlation coefficient, 0.945; 95% confidence interval, 0.932-0.956; κ=0.837; P<0.001). Data for fetal head station and head position showed a fair correlation (κ=0.353 and κ=0.554, respectively; both P<0.001). The majority of women (186/215, 87%) reported a preference for ultrasonography over DVE for assessment of labor progression in a future pregnancy. Intrapartum ultrasonography was preferred as an objective assessment tool for labor progression among term nulliparous women and therefore should be practiced in all labor rooms. Further studies on interobserver variation are recommended to establish the reproducibility of intrapartum assessment by ultrasonography.

Risk factors associated with subgaleal hemorrhage in neonates exposed to vacuum extraction.

Subgaleal hemorrhage (SGH) is a life-threatening neonatal condition that is strongly associated with vacuum assisted delivery (VAD). The factors associated with the development of SGH following VAD are not well-established. We aimed to evaluate the factors associated with the development of SGH following attempted VAD. A retrospective case-control study of women who delivered at a tertiary university-affiliated medical center in Jerusalem, Israel, during 2009-2018. Cases comprised all parturients with singleton pregnancies for whom attempted VAD resulted in neonatal SGH. A control group of VAD attempts was established by matching one-to-one according to gestational age at delivery, parity and year of delivery. Fetal, intrapartum and vacuum procedure characteristics were compared between the groups. In all, 313 (89.5%) of the 350 attempted VAD were nulliparous. Baseline maternal and fetal characteristics were similar between the groups except for higher neonatal birthweight in the SGH group. In multivariate logistic regression analysis, only six independent risk factors were significantly associated with the development of SGH: second-stage duration (for each 30-minute increase, adjusted odds ratio [OR] 1.13; 95% confidence intervals [CI] 1.04-1.25; P= .006), presence of meconium-stained amniotic fluid (adjusted OR 2.61; 95% CI 1.52-4.48; P= .001), presence of caput succedaneum (adjusted OR 1.79; 95% CI 1.11-2.88; P= .01), duration of VAD (for each 3-minute increase, adjusted OR 2.04; 95% CI 1.72, 2.38; P < .001), number of dislodgments (adjusted OR 2.38; 95% CI 1.66-3.44; P < .001), and fetal head station (adjusted OR 3.57; 95% CI 1.42-8.33; P= .006). Receiver operating characteristic curves showed that VAD duration of ≥15minutes had a 96.7% sensitivity and 75.0% specificity in predicting SGH formation, with an area under the curve equal to .849. Vacuum duration, the number of dislodgments, the duration of second stage of delivery, fetal head station, the presence of caput succedaneum and the presence of meconium were found to be independently associated with SGH formation.

Labor progress determined by ultrasound is different in women requiring cesarean delivery from those who experience a vaginal delivery following induction of labor

The diagnosis of labor dystocia generally is determined by the deviation of labor progress, which is assessed by the use of a partogram. Recently, intrapartum transperineal ultrasound for the assessment of fetal head descent has been introduced to assess labor progress in the first stage of labor in a more objective and noninvasive way. The objective of the study was to determine the differences in labor progress by the use of serial transperineal ultrasound assessment of fetal head descent between women having vaginal and cesarean delivery. This was a prospective longitudinal study performed in 315 women with singleton pregnancy who were undergoing labor induction at term between December 2016 and December 2017. Paired assessment of cervical dilation and fetal head station by vaginal examination and transperineal ultrasonographic assessment of parasagittal angle of progression and head-perineum distance were made serially after the commencement of labor induction. According to the hospital protocol, assessment was performed every 24 hours and 4 hours, respectively, during latent and active phases of labor. The researchers and the clinical team were blinded to each other's findings. The repeated measures data were analyzed by mixed effect models. To determine the effect of mode of delivery on the association between parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation, the significance of the interaction term between each mode of delivery and fetal head station or cervical dilation was determined, which accounted for parity and obesity. Area under receiver-operating characteristic curve was used to evaluate the performance of serial intrapartum sonography in predicting women with cesarean delivery because of failure to progress. The total number of paired vaginal examination and ultrasound assessments was 1198, with a median of 3 per woman. The median assessment-to-assessment interval was 4.6 hours (interquartile range, 4.3-5.1 hours). Women who achieved vaginal delivery (n=261) had steeper slopes of parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation than those who achieved cesarean delivery (n=54). Objectively, an additional decrease of 5.11 and 1.37 degrees in parasagittal angle of progression was observed for an unit increase in fetal head station and cervical dilation, respectively, in women who required cesarean delivery (P<.01; P=.01), compared with women who achieved vaginal delivery, after taking account of repeated measures from individuals and confounding factors. The respective additional increases in head-perineum distance for a unit increase in fetal head station and cervical dilation were 0.27 cm (P<.01) and 0.12 cm (P<.01). A combination of maternal characteristics with the temporal changes of parasagittal angle of progression for an unit increase in fetal head station achieved an area under receiver-operating characteristic curve of 0.85 (95% confidence interval, 0.76-0.94), with sensitivity of 79% and specificity of 80%, for the prediction of women who required cesarean delivery because of failure to progress. The differences in labor progress between vaginal and cesarean delivery have been illustrated objectively by serial intrapartum transperineal ultrasonographic assessment of fetal head descent. This tool is potentially predictive of women who will require cesarean delivery because of failure to progress.

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

The traditional approach to the assessment of labor progress is by digital vaginal examination; however, it is subjective and imprecise. Recent studies have investigated the role of transperineal ultrasonographic assessment of fetal head descent by measuring the angle of progression and head-perineum distance. The objective of this study was to evaluate factors that affected labor progress, which were defined by the transperineal ultrasonographic parameters, in women who achieved vaginal delivery. This was a prospective longitudinal study performed in 315 women with singleton pregnancy who underwent labor induction at term between December 2016 and December 2017. Paired assessment of cervical dilation and fetal head station by vaginal examination and transperineal ultrasonographic assessment of fetal head descent (parasagittal angle of progression and head-perineum distance) were made serially after the commencement of labor induction until full cervical dilation. The researchers were blinded to the findings of the clinical team's vaginal examination and vice versa. The repeated measure data were analyzed by mixed effect models to identify the significant factors (age ≥35 years, obesity, parity, methods of labor induction, and epidural anesthesia) that affected the relationship between parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation. The total number of paired vaginal examination and transperineal ultrasonographic assessments among the 261 women (82.9%) with vaginal delivery was 945, with a median of 3 per woman. The median assessment-to-assessment interval was 4.6 hours (interquartile range, 4.3-5.2). Multiparity and mechanical methods of labor induction were associated with a faster rate of fetal head descent, which was determined by head-perineum distance against fetal head station, than nulliparity and the use of a slow-release vaginal pessary, respectively. An additional increase of 0.10 cm in head-perineum distance was observed, for an unit increase in fetal head station in nulliparous women (P=.03) and women who had a slow-release vaginal pessary (P=.02), compared with multiparous women and those who had mechanical methods for labor induction. The use of epidural anesthesia was associated with a slower rate of fetal head descent, which was determined by both parasagittal angle of progression and head-perineum distance, against fetal head station. An additional decrease of 3.66 degrees in parasagittal angle of progression (P=.04) and an additional increase in 0.33 cm in head-perineum distance (P≤.001) were observed for a unit increase in fetal head station in women with the use of epidural anesthesia, compared with those without. Obese women had higher head-perineum distance overall, compared with normal weight women; at different cross-sections of time periods, obesity appeared to be associated with a slower rate of change between head-perineum distance and cervical dilation. Advanced maternal age did not affect transperineal ultrasound-determined labor progress (P>.05). Parity, methods of labor induction, the use of epidural anesthesia, and obesity affect labor progress, which has been illustrated objectively by serial transperineal ultrasonographic assessment of fetal head descent.

Looking back: sectio in mortua and the role of the midwife

Operative vaginal delivery and, in particular, rotational forceps delivery require extensive training, specific skills, and dexterity. Performed correctly, it can reduce the need for difficult late second-stage cesarean delivery and its associated complications. When rotation to occiput anterior position is achieved, pelvic trauma and anal sphincter injury commonly associated with direct delivery from occiput posterior positions may be avoided.We report the original and novel use of real-time intrapartum ultrasound simultaneously during Kielland’s rotational forceps delivery to monitor correct execution and increase maternal safety.This is a prospective observational study performed at the Charité University Hospital in Berlin between 2013 and 2018. Simultaneous, real-time, intrapartum suprapubic ultrasound during Kielland’s rotational forceps deliveries were performed in a series of laboring women with normal fetuses and arrest of labor in the late second stage and with a fetal head malposition, requiring operative vaginal delivery. In addition to vaginal palpation for head station, rotation, and asynclitism, intrapartum ultrasound was also used to objectively determine head station, head direction, and midline angle. The operator was not blinded to the ultrasound findings.The delivering obstetrician examined the woman and performed the delivery. An assistant, trained in intrapartum ultrasound, placed a curved-array transducer transversely in the midline just above the pubic bone to display the forceps blades being applied and the rotation of the fetal head in occiput anterior position.In all 32 laboring women included in the study, the blades were applied correctly and the fetal heads successfully rotated to an occiput anterior position with direct ultrasound confirmation, and vaginal delivery was achieved. There were no cases of difficult application, repeat application, slippage of the blades, or rotation of the fetal head in the wrong direction. Maternal outcomes showed no vaginal tears, cervical tears, or postpartum hemorrhage >500 mL. There was 1 case of third-degree perineal tear (3a). Neonatal outcomes included mild hyperbilirubinemia (n=1), small cephalohematoma conservatively managed (n=1), and early-onset group B streptococcus sepsis secondary to maternal colonization (n=1). There were no neonatal deaths.Ultrasound guidance during Kielland’s rotational forceps delivery is an original and novel approach. We describe the use of intrapartum ultrasound in assessing fetal head station and position and also to simultaneously and objectively monitor performance of rotational forceps delivery. Intrapartum ultrasound enhances operator confidence and, possibly, patient safety. It is a valuable adjunct to obstetrical training and can improve learning efficiency. Real-time ultrasound guidance of fetal head rotation to occiput anterior position with Kielland’s forceps may also protect the perineum and reduce anal sphincter injury. This novel approach can lead to a renaissance in the safe use of Kielland’s forceps.

Pre-Induction Transperineal Ultrasound Assessment for the Prediction of Labor Outcome

Objective: To examine (1) the concordance of manual and automated para-symphyseal angle of progression (psAOP) measurements, (2) the repeatability of psAOP, head-symphysis distance, head-perineum distance, and sonographic cervical dilatation, and (3) the value of transperineal ultrasound (TPU) in predicting induction of labor (IOL) outcome. Methods: We performed a prospective study in 308 women with singleton pregnancies undergoing IOL at term. Logistic regression analysis was used to determine which maternal factors, Bishop score, method of IOL, and TPU parameters were significant predictors of cesarean section (CS) and CS due to no progress (CS-NP). Results: There was vaginal delivery in 225 (83.0%) and CS in 46 (17.0%) cases. The intra-class correlation coefficient between manual and automated psAOP was 0.866, but automated psAOP was 4.6° wider than manual measurement. All TPU parameters had an inter-observer intra-class correlation coefficient > 0.800. Significant independent prediction of CS and CS-NP was provided by maternal factors, previous vaginal delivery, and psAOP. There was no improvement in area under the receiver-operating characteristic curve with the addition of psAOP to maternal factors. Conclusions: All TPU parameters are reproducible. Comparing the three TPU parameters for fetal head station, only psAOP is a significant independent predictor of CS; however, it is unlikely to be useful in predicting IOL outcome.

The feasibility and accuracy of ultrasound assessment in the labor room

Objective: Vaginal examination is widely used to assess the progress of labor; however, it is subjective and poorly reproducible. We aim to assess the feasibility and accuracy of transabdominal and transperineal ultrasound compared to vaginal examination in the assessment of labor and its progress.Methods: Women were recruited as they presented for assessment of labor to a tertiary inner city maternity service. Paired vaginal and ultrasound assessments were performed in 192 women at 24–42 weeks. Fetal head position was assessed by transabdominal ultrasound defined in relation to the occiput position transformed to a 12-hour clock face; fetal head station defined as head-perineum distance by transperineal ultrasound; cervical dilatation by anterior to posterior cervical rim measurement and caput succedaneum by skin-skull distance on transperineal ultrasound.Results: Fetal head position was recorded in 99.7% (298/299) of US and 51.5% (154/299) on vaginal examination (p < .00011). Bland–Altman analysis showed 95% limits of agreement, −5.31 to 4.84 clock hours. Head station was recorded in 96.3% (308/320) on vaginal examination (VE) and 95.9% (307/320) on US (p = .791). Head station and head perineum distance were negatively correlated (Spearman’s r = −.57, p < .0001). 54.4% (178/327) of cervical dilatation measurements were determined using US and 100% on VE/speculum (p < .0001). Bland–Altman analysis showed 95% limits of agreement −2.51–2.16 cm. The presence of caput could be assessed in 98.4% (315/320) of US and was commented in 95.3% (305/320) of VEs, with agreement for the presence of caput of 76% (p < .05). Fetuses with caput greater than 10 mm had significantly lower head station (p < .0001).Conclusions: We describe comprehensive ultrasound assessments in the labor room that could be translated to the assessment of women in labor. Fetal head position is unreliably determined by vaginal examination and agrees poorly with US. Head perineum distance has a moderate correlation with fetal head station in relation to the ischial spines based on vaginal examination. Cervical dilatation is not reliably assessed by ultrasound except at dilatations of less than 4 cm. Caput is readily quantifiable by ultrasound and its presence is associated with lower fetal head station. Transabdominal and transperineal ultrasound is feasible in the labor room with an accuracy that is generally greater than vaginal examinations.

Use of the purple line to diagnose cervical dilatation and fetal head station during labor.

Purple line had high incidence but was not suitable for diagnosing cervical dilatation and fetal head station owing to low accuracy.

Sonographic parameters for diagnosing fetal head engagement during labour.

The purpose of this study was to investigate the diagnostic performance of the head-perineum distance, angle of progression, and the head-symphysis distance as intrapartum ultrasound parameters in the determination of an engaged fetal head. Two hundred and one women in labour underwent both ultrasound and digital vaginal examination in the estimation of fetal head station. The transperineal ultrasound measured head-perineum distance, angle of progression, and head-symphysis distance for values correlating with digital vaginal examination head station. Using station 0 as the minimum level of head engagement, correlating cut-off values for head-perineum distance, angle of progression, and head-symphysis distance were obtained. Receiver operating characteristics were used in determining the diagnostic performance of these cut-off values for the detection of fetal head engagement. With head-perineum distance of 3.6 cm the sensitivity and specificity of sonographic determination of engaged fetal head were 78.7 and 72.3%, respectively. A head-symphysis distance of 2.8 cm also had sensitivity and specificity of 74.5 and 70.8%, respectively, in determining engagement, whilst an angle of progression of 101° was consistent with engagement by digital vaginal examination with 68.1% sensitivity and 68.2% specificity. Ultrasound shows high diagnostic performance in determining engaged fetal head at a head-perineum distance of ≤3.6 cm, head-symphysis distance of ≤2.8 cm, and angle of progression of ≥ 101°.

Incidence and risk factors of severe lacerations during forceps delivery in a single teaching hospital where simulation training is held annually

This study was conducted to evaluate the incidence of severe lacerations during forceps delivery and the risk factors associated with such delivery in a hospital where simulation training is held annually. The medical records of 857 women who underwent forceps delivery at term with singleton cephalic presentation from 2010 to 2015 were reviewed. The relationship between clinical characteristics and birth canal trauma was analyzed. Birth canal trauma included third and fourth degree perineal lacerations. Univariable and multivariable models of logistic regression were employed to estimate the raw odds ratio and were adjusted for cofactors with 95% confidence intervals. Statistical significance was defined as P < 0.05. The incidence of severe lacerations was 10.1%. Birth weight, fetal head station, the rate of malrotation and the number of extractions were higher in women with severe lacerations (P < 0.01), whereas the use of obstetric anesthesia was lower in women with such lacerations (P < 0.01). Neither the indication for forceps delivery nor the qualifications of the operator had any influence on the incidence of severe lacerations. The incidence of severe lacerations was relatively low. Risk factors for severe lacerations with forceps delivery were identified as birth weight, fetal head station, malrotation and the number of extractions. Obstetric anesthesia may protect against severe lacerations.

381: The association between fetal head station at the first diagnosis of the second stage of labor and the risk for operative delivery according to parity

To explore the association between fetal head station at the diagnosis of the 2nd stage of labor and the second stage duration and the risk for operative delivery. A retrospective cohort study of all singleton vertex deliveries in a single tertiary center (2010-2016). Women were grouped according to fetal head station upon diagnosis of second stage: above (S<0), at the level (S=0) and below (S>0) the level of the ischial spine. The duration of the 2nd stage and the risk for operative delivery was compared between the study groups. Analysis was stratified by parity. 1) Of 70,021 deliveries during the study period, 35,592 (50.8%) met the inclusion criteria. Amongst, 4,727 (13.3%) were diagnosed with fetal head above, 12,698 (35.7%) were at the level and 18,167 (51.0%) with fetal head below the ischial spine. Of all, 19,539 (54.8%) were nulliparous. 2) The median(IQR) duration of the 2nd stage was 99(48-159) and 16(9-39) minutes for nulliparous and multiparous, respectively. The rate of epidural anesthesia was 86.8% and 77.3% and the rate of spontaneous vaginal delivery was 83.0% and 96.2%, respectively (p<0.001). 3) For nulliparous women, the median duration (95%CI) of the 2nd stage was the shortest in the S>0 group following by S=0 and S<0 groups (149(144-153), 131(128-133) and 73(71-74) minutes, respectively; p<0.001). In multiparous, S>0 group had the shortest duration (14(13-14)) followed by S<0 and S=0 (15(14-16) and 23(22-23) minutes, respectively; p<0.001) (Figure). 4) In multivariable analysis, after controlling for maternal age, gestational age at delivery, pre-pregnancy BMI, spontaneous onset of labor, epidural anesthesia, meconium and first stage duration, the risk for operative delivery was the lowest in the S>0 group (Table). In the S=0 group there was increased risk for cesarean delivery (p<0.05) but not for operative vaginal delivery as compared to the S<0 group (Table). Fetal station at the first diagnosis of the second stage is significantly associated with the duration of the second stage and is significantly correlated with the risk for operative delivery in both nulliparous and multiparous women.View Large Image Figure ViewerDownload Hi-res image Download (PPT)