Assessment Of Fetal Head Descent Research Articles

PSFHS: Intrapartum ultrasound image dataset for AI-based segmentation of pubic symphysis and fetal head

During the process of labor, the intrapartum transperineal ultrasound examination serves as a valuable tool, allowing direct observation of the relative positional relationship between the pubic symphysis and fetal head (PSFH). Accurate assessment of fetal head descent and the prediction of the most suitable mode of delivery heavily rely on this relationship. However, achieving an objective and quantitative interpretation of the ultrasound images necessitates precise PSFH segmentation (PSFHS), a task that is both time-consuming and demanding. Integrating the potential of artificial intelligence (AI) in the field of medical ultrasound image segmentation, the development and evaluation of AI-based models rely significantly on access to comprehensive and meticulously annotated datasets. Unfortunately, publicly accessible datasets tailored for PSFHS are notably scarce. Bridging this critical gap, we introduce a PSFHS dataset comprising 1358 images, meticulously annotated at the pixel level. The annotation process adhered to standardized protocols and involved collaboration among medical experts. Remarkably, this dataset stands as the most expansive and comprehensive resource for PSFHS to date.

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

Determining fetal head descent, expressed as fetal head station and engagement is an essential part of monitoring progression in labor. Assessing fetal head station is based on the distal part of the fetal skull, whereas assessing engagement is based on the proximal part. Prerequisites for assisted vaginal birth are that the fetal head should be engaged and its lowermost part at or below the level of the ischial spines. The part of the fetal head above the pelvic inlet reflects the true descent of the largest diameter of the skull. In molded (reshaped) fetal heads, the leading bony part of the skull may be below the ischial spines while the largest diameter of the fetal skull still remains above the pelvic inlet. An attempt at assisted vaginal birth in such a situation would be associated with risks. Therefore, the vaginal or transperineal assessments of station should be supplemented with a transabdominal examination. We suggest a method for the assessment of fetal head descent with transabdominal ultrasound. To investigate the correlation between transabdominal and transperineal assessment of fetal head descent, and to study fetal head shape at different labor stages and head positions. Women with term singleton cephalic pregnancies admitted to the labor ward for induction of labor or in spontaneous labor, at the Cairo University Hospital and Oslo University Hospital from December 2019 to December 2020 were included. Fetal head descent was assessed with transabdominal ultrasound as the suprapubic descent angle between a longitudinal line through the symphysis pubis and a line from the upper part of the symphysis pubis extending tangentially to the fetal skull. We compared measurements with transperineally assessed angle of progression and investigated interobserver agreement. We also measured the part of fetal head above and below the symphysis pubis at different labor stages. The study population comprised 123 women, of whom 19 (15%) were examined before induction of labor, 8 (7%) in the latent phase, 52 (42%) in the active first stage and 44 (36%) in the second stage. The suprapubic descent angle and the angle of progression could be measured in all cases. The correlation between the transabdominal and transperineal measurements was-0.90 (95% confidence interval,-0.86 to-0.93). Interobserver agreement was examined in 30 women and the intraclass correlation coefficient was 0.98 (95% confidence interval, 0.95-0.99). The limits of agreement were from-9.5 to 7.8 degrees. The fetal head was more elongated in occiput posterior position than in non-occiput posterior positions in the second stage of labor. We present a novel method of examining fetal head descent by assessing the proximal part of the fetal skull with transabdominal ultrasound. The correlation with transperineal ultrasound measurements was strong, especially early in labor. The fetal head was elongated in the occiput posterior position during the second stage of labor.

Predicting the Mode of Delivery by Angle of Progression (AOP) before the Onset of Labor by Transperineal Ultrasound in Nulliparous Women

Background: Prediction of the mode of delivery is crucial for better labour outcome. Recent studies suggest that the angle of progression (AOP), measured using transperineal ultrasound, can substantially aid the assessment of fetal head descent during labor, thereby predicting the mode of delivery. Objective: To assess the ability of the AOP measured by transperineal ultrasound to predict the mode of delivery in nulliparous women before the onset of labor. Methods: A prospective observational study was conducted at our hospital, of nulliparous women who had presented to the antenatal clinic at ≥ 38 weeks of gestation but not in labor. AOP was measured using transperineal ultrasonography and compared among the women having Caesarean section (CS) due to labor dystocia and vaginal delivery (VD). Various other confounding factors which increase the risk of caesarean section were analyzed. Results: Among total 120 nulliparous women, the mean AOP was narrower in patients undergoing CS (n = 28) compared to those with VD (n = 92) (91.6 ± 6.1° vs. 100.7 ± 6.9°; P < 0.01). Multivariable logistic regression analysis revealed that narrow AOP values (OR 3.66; P < 0.001; 95% CI 1.7- 14.5) and occiput-posterior fetal position (OR 1.63; P = 0.04; 95% CI 1.0-7.5) were the independent risk factors for CS. An AOP ≥ 96° (calculated from the ROC curve) was associated with VD in 95% (76/80) of women and an AOP < 96° was observed among 60% (24/40) of women who underwent CS. Conclusion: Narrow AOP (< 96°) and occiput-posterior fetal position are at higher risk for CS due to labor dystocia. AOP measured at the antenatal period could accurately predict the mode of delivery, thereby modifying labor outcome.

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.

Ultrasound in labor: impact of a theoretical and practical course on caregiver’s perspective and accuracy

Objective: The aim of the present study was two-fold; first is to assess the impact of a theoretical and practical course on the caregiver’s perspective on the use of ultrasound in labor. Second is to evaluate the impact of the course on the measurement of the angle of progression.Materials and methods: Obstetricians participating in the course responded twice to a questionnaire addressing the caregiver’s perspective on the use of ultrasound in labor, before and at the end of the course. In addition, all participants measured the angle of progression on a digital simulation software once following the theoretical part and a second time after the conclusion of both the theoretical and practical sessions. All answers to the questionnaire were compared before versus after the course. The angle of progression assessments after the theoretical part and those after the course were compared with those performed by an expert operator.Results: Overall, data from 51 participants were analyzed. In comparison with the pre-course questionnaire, more participants after the course believed ultrasound can be a useful instrument for fetal occiput presentation diagnosis (45; 88.2% versus 26; 51%, p < .001) and for fetal head progression evaluation (37; 72.5% versus 19; 37.3%; p < .001). Although before the course, most participants (32; 62.7%) thought that the transperineal parameters were too complex to be applied, only 19 (37.3%) still considered the complexity of the ultrasound indices, an obstacle against their application in clinical practice after the course (p = .002). Regarding the angle of progression, precourse measurements showed a systematic overestimation in comparison with the gold standard. Furthermore, the coefficient of variation, more than halved following the practical simulation reflecting at least a doubling of the angle of progression (AoP) measurement precision (14.2 versus 5.5%).Conclusions: A theoretical and practical course conducted by expert operators may positively change obstetricians’ perspective on the use of ultrasound in labor. Moreover, a practical session seems to improve the participants’ accuracy and precision in the assessment of fetal head descent by transperineal ultrasound.

Computed tomographic study of anatomical relationship between pubic symphysis and ischial spines to improve interpretation of intrapartum translabial ultrasound.

To analyze the anatomical relationship between the pubic symphysis and the ischial spines to determine reliable landmarks for the assessment of fetal head descent by intrapartum translabial ultrasound (ITU). All computed tomography (CT) scans performed for breech presentation and for twin delivery between 2006 and 2014 in a tertiary university hospital were obtained for measurement and analysis by two operators. The symphysis-left ischial spine angle (SIA) and the symphysis-left ischial spine distance (SID) were measured on three-dimensional reconstructions from the CT volume dataset. We calculated intra- and interobserver agreements for SIA and SID with 95% prediction intervals, created Bland-Altman plots with 95% limits of agreement and estimated the intraclass correlation coefficient (ICC). A sagittal plane projection from the SIA enabled calculation of a sagittal angle, corresponding to the angle of progression (AoP) on ITU. SIA and SID were obtained from CT images from 458 women. Reproducibility was good for both SIA (intraobserver ICC, 0.94 (95% CI, 0.88-0.97) and interobserver ICC, 0.81 (95% CI, 0.66-0.92)) and SID (intraobserver ICC, 0.92 (95% CI, 0.82-0.97) and interobserver ICC, 0.83 (95% CI, 0.73-0.92)). The median SIA was 106° (interquartile range (IQR), 105-109°) and median SID was 26.1 (IQR, 23.4-29.5) mm. SIA and SID were not correlated with pelvic diameter or height. The 50th percentile of AoP was 110°. Knowledge of the anatomical relationship between the pubic symphysis and ischial spines makes it possible to establish a sonographic method for assesssing fetal head descent by taking into account the level of the ischial spines. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

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

To compare longitudinal changes in angle of progression (AoP) and midline angle (MLA) during the active second stage of labor according to the mode of delivery. A three-dimensional transperineal ultrasound volume was acquired in a series of nulliparous women at the beginning of the active second stage (T1) and every 20 min thereafter (T2, T3, T4, T5 and T6). Following delivery, all ultrasound volumes were analyzed and AoP and MLA were measured. Among 71 women included in the study, 58 underwent spontaneous vaginal delivery (group A) and 13 underwent operative delivery (group B) (eight by vacuum extraction and five by Cesarean section). When compared with Group B, Group A had a wider AoP only at T1 (140.0 ± 20.2° vs. 122.9 ± 16.7°; P = 0.010) and T2 (149.7 ± 20.7° vs. 126.9 ± 17.5°; P = 0.006). MLA was narrower in group A only at T3 (21.2 ± 11.7° vs. 40.8 ± 27.9°; P = 0.043), T4 (18.2 ± 15.0° vs. 47.4 ± 29.6°; P = 0.020) and T5 (18.3 ± 6.0° vs. 34.7 ± 4.2°; P = 0.034). On stepwise forward multiple logistic regression analysis, both AoP and MLA were independently associated with operative delivery (OR = 0.955 and OR = 1.018, respectively). Ultrasonographic assessment of fetal head descent in the second stage of labor may play a role in the prediction of the mode of delivery.

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

To assess the reproducibility of measurement of a new sonographic index of fetal head station in labor, the fetal head-symphysis distance (HSD), using three-dimensional ultrasound, and its correlation with digital assessment of fetal head descent and with the angle of progression (AoP). Three-dimensional (3D) ultrasound volumes were acquired from 47 nulliparous women in active labor following assessment of fetal head station with digital examination. The HSD (the distance between the lower edge of the pubic symphysis and the nearest point of the fetal skull) was measured independently by two operators in order to evaluate intra- and interobserver reproducibility. The correlation between HSD, AoP and fetal head station was evaluated using regression analysis. Using 3D tomographic ultrasound imaging (TUI), measurements of the HSD were obtained in different parasagittal planes to evaluate the influence of inaccurate alignment of the probe with the midline of the pelvis. Measurement of HSD showed high intraobserver (intraclass correlation coefficient (ICC) = 0.995; 95% CI, 0.991-0.997) and interobserver (ICC = 0.991; 95% CI, 0.984-0.995) reliability. In addition, a high correlation was demonstrated between mid-sagittal and parasagittal HSD measurements. HSD showed significant negative correlation with both fetal head station and AoP. Fetal HSD is a simple and reliable method for the assessment of fetal head descent in labor.

Ultrasound in labor: a caregiver's perspective

In the last decade, the use of ultrasound in labor has been the subject of much research. Suggested applications include confirmation of fetal viability, identification of fetal presentation and assessment of fetal occiput position and head descent. Nevertheless, it is not clear whether this has changed the practice of caregivers outside the research context; and if it has, it is not clear how. In order to assess this, we performed a survey in April 2012 among participants on courses on prenatal medicine and obstetric ultrasound at the Department of Obstetrics and Gynecology of the Sant'Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy. Participants whose duties included management of labor were invited to answer an online questionnaire. In total, 264 attending physicians completed the questionnaire. The most relevant results are displayed in Table 1. According to our survey, the most popular application of ultrasound in labor was for assessment of fetal occiput position (Table 1). This finding is not surprising given that transabdominal sonographic identification of fetal occiput position is easy to achieve through visualization of anatomical landmarks, such as fetal orbits and the spine, as well as requiring minimal time123. Furthermore, a number of studies have demonstrated the superiority of ultrasound over digital examination for this aim, and are consistent and unequivocal in their support of its use as the gold standard for this clinically important variable123. Sonographic assessment of fetal head position can offer extremely valuable information in certain clinical situations, for instance before instrumental delivery, whereas it seems to be a poor predictor of mode of delivery3, 4. On the other hand, ultrasound was less widely used among survey participants for the assessment of fetal head station and progression (Table 1). We suggest three main obstacles to the application of sonography for this purpose. The first is accessibility to ultrasound equipment; less than half of the participants had an ultrasound machine permanently stationed in their delivery suite. The second obstacle is the absence of convincing data on the utility of ultrasound for this purpose. Lastly, the complexity of the sonographic parameters suggested so far may partially impede the implementation of ultrasound for evaluation of the progression of labor in clinical practice. We acknowledge that more detailed questions about each intrapartum ultrasound parameter would have been useful, however the main goal of this survey was not a comparison between individual parameters. We do also recognize a potential bias in our data. As the chief subject of our courses is ultrasound in obstetrics, the participants who answered the questionnaire are likely to be more experienced in ultrasound than other personnel working in the labor ward. Our survey provides original data on the current use of ultrasonography in the labor ward from the key perspective of the caregiver. It suggests that the publication of more convincing, clinically applicable data and the development of less complex sonographic methods, as encouraged in a recent Opinion article in this Journal3, would promote wider use of intrapartum sonography, especially for the assessment of fetal head descent. A. Youssef*†, T. Ghi†, E. E. Awad‡, E. Maroni†, E. Montaguti†, N. Rizzo† and G. Pilu† †Department of Obstetrics and Gynecology, Sant'Orsola Malpighi Hospital, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy; ‡Department of Obstetrics and Gynecology, El-Shatby Hospital, University of Alexandria, Egypt *Correspondence. (e-mail: [email protected])

P18.04: The assessment of fetal head descent with intrapartum translabial ultrasonography for the safe forced delivery

P18.04: The assessment of fetal head descent with intrapartum translabial ultrasonography for the safe forced delivery

What is the most reliable ultrasound parameter for assessment of fetal head descent?

The aims of this study were, first, to establish the agreement between digital and ultrasound assessment of occipital position and, second, to evaluate the repeatability of the measurements of head direction, angle of the middle line, progression distance and angle of progression in women in the second stage of labor. Digital examination and then transabdominal ultrasound examination was performed on 50 women in the second stage of labor to determine the fetal occipital position. We also obtained three-dimensional (3D) blocks of the fetal head by transperineal sonography, and two experts in 3D ultrasound measured head direction, angle of the middle line, progression distance and angle of progression. Intraclass correlation coefficients with 95% CIs, and Bland-Altman analysis, were used to evaluate intraobserver and interobserver repeatability of measurements. The fetal head position, determined by ultrasound examination, was occiput anterior in 33 (66%) cases and occiput lateral in 17 (34%) cases. Vaginal digital examination failed to identify the correct fetal head position by more than 45° in 33 (66%) cases. All four 3D ultrasound measurements were reproducible but the progression angle had the highest intraclass correlation coefficient for the same observer (0.94; 95% CI, 0.90-0.97) and for two different operators (0.84; 95% CI, 0.73-0.91). The progression angle was also the measurement for which smaller limits of agreement (LOA) were found in the Bland-Altman test, performed to calculate the intraobserver (bias 0.9; LOA, - 9.2 to 11.1%) and interobserver (bias 1.5; LOA, - 15.4 to 18.3%) variability. Digital pelvic examination for determining the fetal head position during labor is not accurate. The most reproducible of the 3D measurements for progression of the fetal head in labor is the progression angle.

Can ultrasound measurements replace digitally assessed elements of the Bishop score?

To compare elements of the Bishop score and corresponding sonographic measurements before induction of labor, and assess how predictive factors can be used in a clinical setting. Prospective comparative clinical study. Secondary referral center, university hospital. A total of 275 women scheduled for induction of labor. Fetal head descent to the perineum was assessed with transperineal ultrasound. Cervical length, posterior angle, and dilatation were evaluated with transvaginal ultrasound followed by Bishop score without knowledge of the ultrasound measurements. Univariable regression analyses of successful induction were significant for digital assessment of cervical dilatation, ultrasound measured fetal head-perineum distance < or =40 mm, ultrasound measured cervical length < or =25 mm, and ultrasound measured posterior cervical angle >90 degrees. After adjusting for maternal factors in a multivariable model, estimates were significant for previous vaginal birth (OR 5.3; 95% CI 2.1-13.9, p<0.01), but borderline for maternal height (OR 1.1; 95% CI 1.0-1.2, p=0.01) and ultrasound measured posterior cervical angle >90 degrees (OR 2.6; 95% CI 1.1-6.1, p=0.03). A scoring model combining ultrasound measured fetal head-perineum distance, cervical length, cervical posterior angle and digitally assessed cervical dilatation, discriminated successful and failed induction at 71% (95% CI 61-80%, p<0.01) area under the receiver-operating characteristics curve. Digital assessment of fetal head descent, cervical length and position can possibly be replaced with ultrasound measurements. Dilatation is best evaluated with digital assessment. Combination of these four factors can predict success of labor induction.

18th World Congress on Ultrasound in Obstetrics and Gynecology, 24–28 August 2008, Chicago, USA: presentations and awards

When asked to introduce Larry Platt as the 2008 Gold Medal recipient, I was more than delighted to do so. One might consider this to be a daunting task. However, since Larry’s career is so robust, it was actually easy to chronicle his contributions through the years. To me, the Ian Donald Gold Medal Award is the greatest honor that one can receive in our field of obstetric and gynecological ultrasonography. Since it carries so much respect, when I heard that Larry Platt was this year’s recipient I thought to myself, ‘it’s about time’. Why? Firstly, Larry has been a prolific contributor to the literature. Secondly, he has been a tenacious supporter of ultrasound education. And thirdly, aside from Stuart Campbell, I can think of no one who has been a greater advocate for ISUOG. He has served as President of the Society, Associate Editor of Ultrasound in Obstetrics and Gynecology, and has been on the Board for many years; he has simply put ISUOG first, ahead of his many other responsibilities. When I recently thumbed through my most recent book on ultrasound, I found that I had cited Larry’s work in five different chapters. First and foremost, one cannot mention his name without connecting it to the wonderful contribution that he and Frank Manning made in designing the biophysical profile. It is hard to believe that this was published 28 years ago, and is still being used in its original form by virtually everyone managing

OP23.06: Intrapartum assessment of fetal head descent: A feasibility study using three dimensional transperineal ultrasound

OP23.06: Intrapartum assessment of fetal head descent: A feasibility study using three dimensional transperineal ultrasound