Automated Approach for Enhancing Fetal Head Station Assessment in Labor with Transperineal Ultrasound.

RATIONALE AND OBJECTIVES: Accurate assessment of fetal head station (FHS) is crucial during labor management to reduce the risk of complications and plan the mode of delivery. Although digital vaginal examination (DVE) has been associated with inaccuracies in FHS assessment, ultrasound (US) evaluation remains dependent on sonographer expertise. This study aimed at investigating the reliability and accuracy of an automatic approach to assess the FHS during labor with transperineal US (TPU). MATERIALS AND METHODS: In this prospective observational study, 27 pregnant women in the second stage of labor, with fetuses in cephalic presentation, underwent conventional labor management with additional TPU examination. A total of 45 2D B-mode TPU acquisitions were performed at different FHS, before performing DVE. The FHS was assessed by the algorithm (FHSaut) on TPU images and by DVE (FHSdig). The sonographic assessment of FHS by expert sonographer (FHSexp) on the same TPU acquisition used for the automatic measurement served as gold standard. The performance and accuracy were assessed through Spearman's ρ, the coefficient of determination (R2), root mean square error (RMSE), and Bland-Altman analysis. RESULTS: A strong correlation between FHSaut and FHSexp (ρ = 0.97, p < 0.001) and a high coefficient of determination (R2 = 0.95) were found. A lower correlation with FHSexp (ρ = 0.66, p < 0.001) and coefficient of determination (R2 = 0.52) was found for DVE. Moreover, the RMSE reported higher accuracy of FHSaut (RMSE = 0.32 cm) compared to FHSdig (RMSE = 0.97 cm). Bland-Altman analysis showed that the algorithm performed with smaller bias and narrower limits of agreement compared to DVE. CONCLUSION: The proposed algorithm can evaluate FHS with high accuracy and low RMSE. This approach could facilitate the use of US in labor, supporting the clinical staff in labor management.

PSFHS challenge report: Pubic symphysis and fetal head segmentation from intrapartum ultrasound images.

Segmentation of the fetal and maternal structures, particularly intrapartum ultrasound imaging as advocated by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) for monitoring labor progression, is a crucial first step for quantitative diagnosis and clinical decision-making. This requires specialized analysis by obstetrics professionals, in a task that i) is highly time- and cost-consuming and ii) often yields inconsistent results. The utility of automatic segmentation algorithms for biometry has been proven, though existing results remain suboptimal. To push forward advancements in this area, the Grand Challenge on Pubic Symphysis-Fetal Head Segmentation (PSFHS) was held alongside the 26th International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI 2023). This challenge aimed to enhance the development of automatic segmentation algorithms at an international scale, providing the largest dataset to date with 5,101 intrapartum ultrasound images collected from two ultrasound machines across three hospitals from two institutions. The scientific community's enthusiastic participation led to the selection of the top 8 out of 179 entries from 193 registrants in the initial phase to proceed to the competition's second stage. These algorithms have elevated the state-of-the-art in automatic PSFHS from intrapartum ultrasound images. A thorough analysis of the results pinpointed ongoing challenges in the field and outlined recommendations for future work. The top solutions and the complete dataset remain publicly available, fostering further advancements in automatic segmentation and biometry for intrapartum ultrasound imaging.

A deep learning approach to identify the fetal head position using transperineal ultrasound during labor.

OBJECTIVES: To develop a deep learning (DL)-model using convolutional neural networks (CNN) to automatically identify the fetal head position at transperineal ultrasound in the second stage of labor. MATERIAL AND METHODS: Prospective, multicenter study including singleton, term, cephalic pregnancies in the second stage of labor. We assessed the fetal head position using transabdominal ultrasound and subsequently, obtained an image of the fetal head on the axial plane using transperineal ultrasound and labeled it according to the transabdominal ultrasound findings. The ultrasound images were randomly allocated into the three datasets containing a similar proportion of images of each subtype of fetal head position (occiput anterior, posterior, right and left transverse): the training dataset included 70 %, the validation dataset 15 %, and the testing dataset 15 % of the acquired images. The pre-trained ResNet18 model was employed as a foundational framework for feature extraction and classification. CNN1 was trained to differentiate between occiput anterior (OA) and non-OA positions, CNN2 classified fetal head malpositions into occiput posterior (OP) or occiput transverse (OT) position, and CNN3 classified the remaining images as right or left OT. The DL-model was constructed using three convolutional neural networks (CNN) working simultaneously for the classification of fetal head positions. The performance of the algorithm was evaluated in terms of accuracy, sensitivity, specificity, F1-score and Cohen's kappa. RESULTS: Between February 2018 and May 2023, 2154 transperineal images were included from eligible participants across 16 collaborating centers. The overall performance of the model for the classification of the fetal head position in the axial plane at transperineal ultrasound was excellent, with an of 94.5 % (95 % CI 92.0--97.0), a sensitivity of 95.6 % (95 % CI 96.8-100.0), a specificity of 91.2 % (95 % CI 87.3-95.1), a F1-score of 0.92 and a Cohen's kappa of 0.90. The best performance was achieved by the CNN1 - OA position vs fetal head malpositions - with an accuracy of 98.3 % (95 % CI 96.9-99.7), followed by CNN2 - OP vs OT positions - with an accuracy of 93.9 % (95 % CI 89.6-98.2), and finally, CNN3 - right vs left OT position - with an accuracy of 91.3 % (95 % CI 83.5-99.1). CONCLUSIONS: We have developed a DL-model capable of assessing fetal head position using transperineal ultrasound during the second stage of labor with an excellent overall accuracy. Future studies should validate our DL model using larger datasets and real-time patients before introducing it into routine clinical practice.

AIDA (Artificial Intelligence Dystocia Algorithm) in Prolonged Dystocic Labor: Focus on Asynclitism Degree.

Asynclitism, a misalignment of the fetal head with respect to the plane of passage through the birth canal, represents a significant obstetric challenge. High degrees of asynclitism are associated with labor dystocia, difficult operative delivery, and cesarean delivery. Despite its clinical relevance, the diagnosis of asynclitism and its influence on the outcome of labor remain matters of debate. This study analyzes the role of the degree of asynclitism (AD) in assessing labor progress and predicting labor outcome, focusing on its ability to predict intrapartum cesarean delivery (ICD) versus non-cesarean delivery. The study also aims to assess the performance of the AIDA (Artificial Intelligence Dystocia Algorithm) algorithm in integrating AD with other ultrasound parameters for predicting labor outcome. This retrospective study involved 135 full-term nulliparous patients with singleton fetuses in cephalic presentation undergoing neuraxial analgesia. Data were collected at three Italian hospitals between January 2014 and December 2020. In addition to routine digital vaginal examination, all patients underwent intrapartum ultrasound (IU) during protracted second stage of labor (greater than three hours). Four geometric parameters were measured using standard 3.5 MHz transabdominal ultrasound probes: head-to-symphysis distance (HSD), degree of asynclitism (AD), angle of progression (AoP), and midline angle (MLA). The AIDA algorithm, a machine learning-based decision support system, was used to classify patients into five classes (from 0 to 4) based on the values of the four geometric parameters and to predict labor outcome (ICD or non-ICD). Six machine learning algorithms were used: MLP (multi-layer perceptron), RF (random forest), SVM (support vector machine), XGBoost, LR (logistic regression), and DT (decision tree). Pearson's correlation was used to investigate the relationship between AD and the other parameters. A degree of asynclitism greater than 70 mm was found to be significantly associated with an increased rate of cesarean deliveries. Pearson's correlation analysis showed a weak to very weak correlation between AD and AoP (PC = 0.36, p < 0.001), AD and HSD (PC = 0.18, p < 0.05), and AD and MLA (PC = 0.14). The AIDA algorithm demonstrated high accuracy in predicting labor outcome, particularly for AIDA classes 0 and 4, with 100% agreement with physician-practiced labor outcome in two cases (RF and SVM algorithms) and slightly lower agreement with MLP. For AIDA class 3, the RF algorithm performed best, with an accuracy of 92%. AD, in combination with HSD, MLA, and AoP, plays a significant role in predicting labor dystocia and labor outcome. The AIDA algorithm, based on these four geometric parameters, has proven to be a promising decision support tool for predicting labor outcome and may help reduce the need for unnecessary cesarean deliveries, while improving maternal-fetal outcomes. Future studies with larger cohorts are needed to further validate these findings and refine the cut-off thresholds for AD and other parameters in the AIDA algorithm.

PSFHSP-Net: an efficient lightweight network for identifying pubic symphysis-fetal head standard plane from intrapartum ultrasound images.

The accurate selection of the ultrasound plane for the fetal head and pubic symphysis is critical for precisely measuring the angle of progression. The traditional method depends heavily on sonographers manually selecting the imaging plane. This process is not only time-intensive and laborious but also prone to variability based on the clinicians' expertise. Consequently, there is a significant need for an automated method driven by artificial intelligence. To enhance the efficiency and accuracy of identifying the pubic symphysis-fetal head standard plane (PSFHSP), we proposed a streamlined neural network, PSFHSP-Net, based on a modified version of ResNet-18. This network comprises a single convolutional layer and three residual blocks designed to mitigate noise interference and bolster feature extraction capabilities. The model's adaptability was further refined by expanding the shared feature layer into task-specific layers. We assessed its performance against both traditional heavyweight and other lightweight models by evaluating metrics such as F1-score, accuracy (ACC), recall, precision, area under the ROC curve (AUC), model parameter count, and frames per second (FPS). The PSFHSP-Net recorded an ACC of 0.8995, an F1-score of 0.9075, a recall of 0.9191, and a precision of 0.9022. This model surpassed other heavyweight and lightweight models in these metrics. Notably, it featured the smallest model size (1.48 MB) and the highest processing speed (65.7909 FPS), meeting the real-time processing criterion of over 24 images per second. While the AUC of our model was 0.930, slightly lower than that of ResNet34 (0.935), it showed a marked improvement over ResNet-18 in testing, with increases in ACC and F1-score of 0.0435 and 0.0306, respectively. However, precision saw a slight decrease from 0.9184 to 0.9022, a reduction of 0.0162. Despite these trade-offs, the compression of the model significantly reduced its size from 42.64 to 1.48 MB and increased its inference speed by 4.4753 to 65.7909 FPS. The results confirm that the PSFHSP-Net is capable of swiftly and effectively identifying the PSFHSP, thereby facilitating accurate measurements of the angle of progression. This development represents a significant advancement in automating fetal imaging analysis, promising enhanced consistency and reduced operator dependency in clinical settings.

Artificial Intelligence, Intrapartum Ultrasound and Dystocic Delivery: AIDA (Artificial Intelligence Dystocia Algorithm), a Promising Helping Decision Support System.

The position of the fetal head during engagement and progression in the birth canal is the primary cause of dystocic labor and arrest of progression, often due to malposition and malrotation. The authors performed an investigation on pregnant women in labor, who all underwent vaginal digital examination by obstetricians and midwives as well as intrapartum ultrasonography to collect four "geometric parameters", measured in all the women. All parameters were measured using artificial intelligence and machine learning algorithms, called AIDA (artificial intelligence dystocia algorithm), which incorporates a human-in-the-loop approach, that is, to use AI (artificial intelligence) algorithms that prioritize the physician's decision and explainable artificial intelligence (XAI). The AIDA was structured into five classes. After a number of "geometric parameters" were collected, the data obtained from the AIDA analysis were entered into a red, yellow, or green zone, linked to the analysis of the progress of labor. Using the AIDA analysis, we were able to identify five reference classes for patients in labor, each of which had a certain sort of birth outcome. A 100% cesarean birth prediction was made in two of these five classes. The use of artificial intelligence, through the evaluation of certain obstetric parameters in specific decision-making algorithms, allows physicians to systematically understand how the results of the algorithms can be explained. This approach can be useful in evaluating the progress of labor and predicting the labor outcome, including spontaneous, whether operative VD (vaginal delivery) should be attempted, or if ICD (intrapartum cesarean delivery) is preferable or necessary.

RTSeg-net: A lightweight network for real-time segmentation of fetal head and pubic symphysis from intrapartum ultrasound images.

The segmentation of the fetal head (FH) and pubic symphysis (PS) from intrapartum ultrasound images plays a pivotal role in monitoring labor progression and informing crucial clinical decisions. Achieving real-time segmentation with high accuracy on systems with limited hardware capabilities presents significant challenges. To address these challenges, we propose the real-time segmentation network (RTSeg-Net), a groundbreaking lightweight deep learning model that incorporates innovative distribution shifting convolutional blocks, tokenized multilayer perceptron blocks, and efficient feature fusion blocks. Designed for optimal computational efficiency, RTSeg-Net minimizes resource demand while significantly enhancing segmentation performance. Our comprehensive evaluation on two distinct intrapartum ultrasound image datasets reveals that RTSeg-Net achieves segmentation accuracy on par with more complex state-of-the-art networks, utilizing merely 1.86 M parameters-just 6 % of their hyperparameters-and operating seven times faster, achieving a remarkable rate of 31.13 frames per second on a Jetson Nano, a device known for its limited computing capacity. These achievements underscore RTSeg-Net's potential to provide accurate, real-time segmentation on low-power devices, broadening the scope for its application across various stages of labor. By facilitating real-time, accurate ultrasound image analysis on portable, low-cost devices, RTSeg-Net promises to revolutionize intrapartum monitoring, making sophisticated diagnostic tools accessible to a wider range of healthcare settings.

The use of intrapartum ultrasound in operative vaginal birth: a retrospective cohort study.

BACKGROUND: Poor outcomes from operative vaginal birth have been associated with failure to recognize malposition, breakdown in interdisciplinary communication, and deviation from accepted guidelines. We recently implemented a safety bundle including routine intrapartum ultrasound and a structured time-out and procedural checklist aiming to reduce maternal and perinatal morbidity from operative vaginal birth. OBJECTIVE: This study aimed to compare births where intrapartum ultrasound was used and those where it was not used during a safety bundle implementation period at Monash Health. STUDY DESIGN: We performed a retrospective cohort study at Monash Health during the transitional phase of implementing an operative vaginal birth safety bundle. We studied all women with operative vaginal birth and fully dilated cesarean delivery with a singleton cephalic term fetus. We compared births for which intrapartum ultrasound was used and those for which it was not. The primary outcome was neonates delivered in an unexpected position. Neonatal and maternal morbidity were also assessed, including a neonatal composite of Apgar score <7 at 5 minutes, cord lactate >8 mmol/L, need for resuscitation, significant birth trauma, or neonatal intensive care unit admission. To control for confounding by indication, we estimated propensity scores for the probability of using intrapartum ultrasound for each case based on maternal and labor characteristics, and adjusted the effect estimates for the propensity scores using multivariable logistic regression models. RESULTS: From August 2022 to July 2023, there were 1205 operative vaginal births or fully dilated cesarean deliveries at Monash Health, including 743 (61.7%) forceps, 346 (28.7%) vacuum, and 116 (9.6%) fully dilated cesarean deliveries. Over this time, we observed increased uptake of intrapartum ultrasound from 26% in August 2022 to 60% (P<.001) in July 2023, of the time-out from 21% to 58% (P<.001), and the checklist from 33% to 80% (P<.001) of operative second-stage births. Among the births where intrapartum ultrasound was used (n=509), compared with those where it was not (n=696), there were significantly more forceps births (67% vs 58%; adjusted odds ratio, 1.35; 95% confidence interval, 1.05-1.74; P=.021) and a reduction in vacuum births (24% vs 32%; adjusted odds ratio, 0.77; 95% confidence interval, 0.58-1.01; P=.059). There were no significant differences in fully dilated cesarean delivery or maternal morbidity. Intrapartum ultrasound use was associated with significantly fewer infants being delivered in an unexpected position (0.2% vs 2.2%; adjusted odds ratio, 0.08; 95% confidence interval, 0.00-0.44; P=.019) and a significant reduction in composite neonatal morbidity (22% vs 25%; adjusted odds ratio, 0.73; 95% confidence interval, 0.54-0.97; P=.031). CONCLUSION: During the implementation of a safety bundle, the use of ultrasound before operative vaginal birth was associated with fewer infants delivered in an unexpected position and reduced neonatal morbidity.

A new course on assisted rotational birth and complex caesarean section - Mixed methods evaluation of Art & Craft.

OBJECTIVES: To assess the utility of Art & Craft - a new, hands-on course on Advanced Rotational Techniques and safe Caesarean biRth at Advanced/Full dilation Training aimed at senior Obstetrics trainees. The aims were to assess whether it improved confidence and skills in rotational vaginal birth, impacted fetal head at caesarean, and ultrasound for fetal position. STUDY DESIGN: With ethical approval, pre- and post- course questionnaires and post- course interviews of attendees were conducted. A pre course questionnaire was emailed 1 week before the course. Attendees were asked to rate their confidence levels in performing vaginal examination and ultrasound assessment of fetal position, rotational ventouse, manual rotation, Kielland's rotational forceps, and disimpaction of the fetal head during second stage caesarean on a scale of 1 to 5. 1 = not confident at all and 5 = very confident. A post-course questionnaire with the same questions was emailed 3 days after. p values for differences in scores were calculated using the Wilcoxon signed rank test using Stata/MP 18 software. RESULTS: 32 trainees attended the course. 28 questionnaires were available for analysis. The majority 39 % were middle grade (ST3-ST5) level. Initial confidence was very low for rotational forceps (median 1/5). After attending the course and practical stations, respondents' confidence levels increased significantly (p < 0.05) across all domains; vaginal examination from 4 to 5, ultrasound for fetal position, rotational ventouse, and manual rotation from 3 to 5, disimpaction from 4 to 4.5, and Kielland's rotational forceps from 1 to 4. Nine participated in post course interviews, which were thematically analysed. Participants expressed that the course gave them the opportunity to ask specific questions from experts to improve their confidence. A barrier to learning new methods was highlighted in that it is difficult to receive practical training in Kielland's, resulting in low confidence. CONCLUSION: A practical, hands-on course on complex operative birth significantly increases trainee confidence levels in vaginal examination, ultrasound for fetal position, disimpaction, and techniques for rotational vaginal birth. The evaluation highlights that continued education and practise is required, even when trainees are senior. Evaluation of clinical outcomes after training is needed; and planned.

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

BACKGROUND AND OBJECTIVES: Accurate diagnosis of labor progress is crucial for making well-informed decisions regarding timely and appropriate interventions to optimize outcomes for both the mother and the fetus. The aim of this study was to assess the progress of the second stage of labor using intrapartum ultrasound. MATERIAL AND METHODS: This was a prospective study (December 2022-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Maternal-fetal and labor characteristics were recorded, and two ultrasound parameters were measured: the angle of progression (AoP) and the head-perineum distance (HPD). The correlation between the two ultrasonographic values and the maternal-fetal characteristics was investigated. Multinomial regression analysis was also conducted to investigate any potential predictors of the mode of delivery. RESULTS: A total of 82 women at the second stage of labor were clinically and sonographically assessed. The mean duration of the second stage of labor differed between vaginal and cesarean deliveries (65.3 vs. 160 min; p-value < 0.001) and between cesarean and operative vaginal deliveries (160 vs. 88.6 min; p-value = 0.015). The occiput anterior position was associated with an increased likelihood of vaginal delivery (OR: 24.167; 95% CI: 3.8-152.5; p-value < 0.001). No significant differences were identified in the AoP among the three different modes of delivery (vaginal: 145.7° vs. operative vaginal: 139.9° vs. cesarean: 132.1°; p-value = 0.289). The mean HPD differed significantly between vaginal and cesarean deliveries (28.6 vs. 41.4 mm; p-value < 0.001) and between cesarean and operative vaginal deliveries (41.4 vs. 26.9 mm; p-value = 0.002); it was correlated significantly with maternal BMI (r = 0.268; p-value = 0.024) and the duration of the second stage of labor (r = 0.256; p-value = 0.031). Low parity (OR: 12.024; 95% CI: 6.320-22.876; p-value < 0.001) and high HPD (OR: 1.23; 95% CI: 1.05-1.43; p-value = 0.007) were found to be significant predictors of cesarean delivery. CONCLUSIONS: The use of intrapartum ultrasound as an adjunctive technique to the standard clinical evaluation may enhance the diagnostic approach to an abnormal labor progress and predict the need for operative vaginal or cesarean delivery.

Oxytocin augmentation and neurotransmitters in prolonged delivery: An experimental appraisal.

The uterus is a highly innervated organ, and during labor, this innervation is at its highest level. Oxytocinergic fibers play an important role in labor and delivery and, in particular, the Lower Uterine Segment, cervix, and fundus are all controlled by motor neurofibers. Oxytocin is a neurohormone that acts on receptors located on the membrane of the smooth cells of the myometrium. During the stages of labor and delivery, its binding causes myofibers to contract, which enables the fundus of the uterus to act as a mediator. The aim of this study was to investigate the presence of oxytocinergic fibers in prolonged and non-prolonged dystocic delivery in a cohort of 90 patients, evaluated during the first and second stages of labor. Myometrial tissue samples were collected and evaluated by electron microscopy, in order to quantify differences in neurofibers concentrations between the investigated and control cohorts of patients. The authors of this experiment showed that the concentration of oxytocinergic fibers differs between non-prolonged and prolonged dystocic delivery. In particular, in prolonged dystocic delivery, compared to non-prolonged dystocic delivery, there is a lower amount of oxytocin fiber. The increase in oxytocin appeared to be ineffective in patients who experienced prolonged dystocic delivery, since the dystocic labor ended as a result of the altered presence of oxytocinergic fibers detected in this group of patients.

The sonopartogram.

The assessment of labor progress from digital vaginal examination has remained largely unchanged for at least a century, despite the current major advances in maternal and perinatal care. Although inconsistently reproducible, the findings from digital vaginal examination are customarily plotted manually on a partogram, which is composed of a graphical representation of labor, together with maternal and fetal observations. The partogram has been developed to aid recognition of failure to labor progress and guide management-specific obstetrical intervention. In the last decade, the use of ultrasound in the delivery room has increased with the advent of more powerful, portable ultrasound machines that have become more readily available for use. Although ultrasound in intrapartum practice is predominantly used for acute management, an ultrasound-based partogram, a sonopartogram, might represent an objective tool for the graphical representation of labor. Demonstrating greater accuracy for fetal head position and more objectivity in the assessment of fetal head station, it could be considered complementary to traditional clinical assessment. The development of the sonopartogram concept would require further undertaking of serial measurements. Advocates of ultrasound will concede that its use has yet to demonstrate a difference in obstetrical and neonatal morbidity in the context of the management of labor and delivery. Taking a step beyond the descriptive graphical representation of labor progress is the question of whether a specific combination of clinical and demographic parameters might be used to inform knowledge of labor outcomes. Intrapartum cesarean deliveries and deliveries assisted by forceps and vacuum are all associated with a heightened risk of maternal and perinatal adverse outcomes. Although these outcomes cannot be precisely predicted, many known risk factors exist. Malposition and high station of the fetal head, short maternal stature, and other factors, such as caput succedaneum, are all implicated in operative delivery; however, the contribution of individual parameters based on clinical and ultrasound assessments has not been quantified. Individualized risk prediction models, including maternal characteristics and ultrasound findings, are increasingly used in women's health-for example, in preeclampsia or trisomy screening. Similarly, intrapartum cesarean delivery models have been developed with good prognostic ability in specifically selected populations. For intrapartum ultrasound to be of prognostic value, robust, externally validated prediction models for labor outcome would inform delivery management and allow shared decision-making with parents.

Intrapartum ultrasound in maternal lateral versus semi-recumbent posture. A repeated measures study.

OBJECTIVE: This study aimed to assess whether intrapartum ultrasound (ITU) measurements in maternal lateral posture are superimposable to ITU measurements in semi-recumbent position. STUDY DESIGN: A single-center, repeated measures design was used. Women in the second stage of labor were randomized to ITU first in semi-recumbent followed by ITU in side-lying posture without and with contraction, or inversely. The angle of progression (AOP) and the head-perineum distance (HPD) between contractions (AOP1 and HPD1) and with contraction (AOP2 and HPD2) were measured in each maternal posture. The differences between AOP1 and AOP2 (dAOP), and between HPD1 and HPD2 (dHPD) were calculated. RESULTS AND CONCLUSIONS: Forty-two women participated in the study. A generalized estimating equation model showed that AOP1 (-3.00°; 95 % CI -5.77 to -0.23; p = 0.03) and AOP2 (-4.14°; 95 % CI -7.20 to -1.08; p = 0.008) were lower in semi-recumbent compared to maternal lateral posture. HPD1 (+1.43 mm; 95 % CI 0.05-2.81; p = 0.042) and HPD2 (+1.53 mm; 95 % CI 0.17-2.89; p = 0.03) were higher in semi-recumbent position. Differences in the ITU measurements in maternal lateral posture compared to semi-recumbent position are small. Monitoring the second stage of labor with ITU in lateral maternal posture is possible.

Intrapartum ultrasound for fetal head asynclitism: Is it possible to establish a degree of asynclitism to correlate to delivery outcome?

OBJECTIVE: To investigate the role of intrapartum ultrasound (IU) in the diagnosis of asynclitism and the importance of asynclitism degree in labor outcomes. METHOD: This prospective cohort study included 41 low-risk pregnant women with fetus in singleton-vertex. The IU assessment to diagnose asynclitism was performed during labor at two specific steps, including the suspicion and/or diagnosis of labor arrest. The "four-chamber view" and "squint sign without nose" were classified as marked/severe asynclitism. The "midline deviation" and "squint sign with nose" findings were classified as moderate asynclitism. Obstetric outcomes and maternal-fetal complications were compared with the degree of asynclitism. RESULTS: Severe and moderate asynclitism was seen in 17 (41.7%), 10 (58.8%) and seven (41.2%) women, respectively. All pregnant women diagnosed with asynclitism delivered by vacuum extraction (VE) or cesarean section (CS). CS was performed in nine patients with asynclitism (52.9%). The difference between asynclitism type and VE/CS ratios was statistically significant (P = 0.039). Four fetuses with squint sign without nose delivered by VE. A significant correlation was seen between the presence of squint without nose sign and second-/third-degree perineal injury. CONCLUSION: Severe asynclitism is associated with increasing operative birth and maternal-fetal complications. Detection of asynclitism degree by IU could be useful, alerting the obstetrics team to possible perinatal problems during delivery.

Can Intrapartum Ultrasonography Improve the Placement of the Vacuum Cup in Operative Vaginal Deliveries?

Although the fetal head position has traditionally been evaluated by digital examination (DE), it has a failure rate ranging between 20 and 70%; hence, intrapartum transabdominal ultrasonography (TUS) has become relevant. We aimed to evaluate the utility of the TUS to identify the fetal head positions in vacuum-assisted deliveries. We performed a prospective observational study including 101 pregnant patients in active labor who required a vacuum-assisted delivery. The fetal head position was assessed by a DE and a TUS prior to vacuum cup placement. After delivery, the optimal vacuum cup placement was evaluated as the distance between the chignon and the flexion point ≤2 cm. The general concordance rate between the DE and TUS was 72.2%, with the poorest concordance rate for occiput posterior positions at 46.1%. In five cases (4.9%), it was not possible to determine the fetal head position through the DE. The correlation was higher in low and medium planes, with 77% and 68.1% concordance rates, respectively, while it was lower in high planes (60%). In 90.1% of cases, the vacuum cup placement was optimal. Our findings show that intrapartum transabdominal ultrasonography is a useful technique to identify the fetal head position allowing optimal placement of the vacuum cup necessary for correct vacuum-assisted delivery.

Prognostic accuracy of ultrasound measures of fetal head descent to predict outcome of operative vaginal birth: a comparative systematic review and meta-analysis.

OBJECTIVE: This study aimed to compare the prognostic accuracy of intrapartum transperineal ultrasound measures of fetal descent before operative vaginal birth in predicting complicated or failed procedures. DATA SOURCES: We performed a predefined systematic search in Medline, Embase, CINAHL, and Scopus from inception to June 10, 2022. STUDY ELIGIBILITY CRITERIA: We included studies assessing the following intrapartum transperineal ultrasound measures before operative vaginal birth to predict procedure outcome: angle of progression, head direction, head-perineum distance, head-symphysis distance, midline angle, and/or progression distance. METHODS: Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Bivariate meta-analysis was used to pool sensitivities and specificities into summary receiver operating characteristic curves for each intrapartum transperineal ultrasound measure. Subgroup analyses were performed for measures taken at rest vs with pushing and prediction of failed vs complicated operative vaginal birth. RESULTS: Overall, 16 studies involving 2848 women undergoing attempted operative vaginal birth were included. The prognostic accuracy of intrapartum transperineal ultrasound measures taken at rest to predict failed or complicated operative vaginal birth was high for angle of progression (area under the receiver operating characteristic curve, 0.891; 9 studies) and progression distance (area under the receiver operating characteristic curve, 0.901; 3 studies), moderate for head direction (area under the receiver operating characteristic curve, 0.791; 6 studies) and head-perineum distance (area under the receiver operating characteristic curve, 0.747; 8 studies), and fair for midline angle (area under the receiver operating characteristic curve, 0.642; 4 studies). There was no study with sufficient data to assess head-symphysis distance. Subgroup analysis showed that measures taken with pushing tended to have a higher area under the receiver operating characteristic curve for angle of progression (0.927; 4 studies), progression distance (0.930; 2 studies), and midline angle (0.903; 3 studies), with a similar area under the receiver operating characteristic curve for head direction (0.802; 4 studies). The prediction of failed vs complicated operative vaginal birth tended to be less accurate for angle of progression (0.837 [4 studies] vs 0.907 [6 studies]) and head direction (0.745 [3 studies] vs 0.810 [5 studies]), predominantly because of lower specificity, and was more accurate for head-perineum distance (0.812 [6 studies] vs 0.687 [2 studies]). CONCLUSION: Angle of progression, progression distance, and midline angle measured with pushing demonstrated the highest prognostic accuracy in predicting complicated or failed operative vaginal birth. Overall, the measurements seem to perform better with pushing than at rest.

Predictive value of head-perineum distance measured at the initiation of the active second stage of labor on the mode of delivery: A prospective cohort study.

OBJECTIVE: The objective was to assess the predictive value of head-perineum distance measured at the initiation of the active second stage of labor on the mode of delivery. MATERIAL AND METHODS: It was a prospective cohort study in an academic Hospital of Rennes, France, from July 1, 2020 to April 4, 2021 including 286 full-term parturients who gave birth to a newborn in cephalic presentation. A double-blind ultrasound measurement of the head-perineum distance was performed during the second phase of labor within five minutes after the onset of pushing efforts. The primary outcome was the mode of delivery (spontaneous vaginal delivery versus instrumental vaginal delivery or cesarean section). We performed a multivariate analysis to determine the predictive value of the head-perineum distance by adjusting on potential confounders. RESULTS: Overall, 199 patients delivered by spontaneous vaginal delivery, 80 by instrumental vaginal delivery, and seven by cesarean section. The head-perineum distance measured at the beginning of pushing efforts was predictive of the mode of delivery with a threshold at 44 mm (crude: sensitivity = 56.8 % and specificity = 79.3 %; adjusted: sensitivity = 79.4 % and specificity = 87.4 %). The risk of medical intervention was higher when the head-perineum distance is>44 mm with an adjusted OR of 2.78 [1.38; 5.76]. CONCLUSION: The head-perineum distance measured at the initiation of the active second stage of labor is predictive of the mode of delivery. Head-perineum distance below 44 mm predicts a vaginal delivery with the best diagnostic performance, and optimizes the time to start pushing efforts.

Intrapartum ultrasound use in clinical practice as a predictor of delivery mode during prolonged second stage of labor.

PURPOSE: To determine the validity of intrapartum ultrasound (IPUS), and particularly the angle of progression (AOP), in predicting delivery mode when measured in real-life clinical practice among women with protracted second stages of labor. METHODS: Using electronic medical records, nulliparous women with a second stage of labor of ≥ 3 h ("prolonged") and a documented AOP measurement during the second stage were identified. The ability of a single AOP measurement in "prolonged" second stage to predict a vaginal delivery (VD) was assessed. Fetal head descent, measured by AOP change/h (calculated from serial measurements), was compared between women who delivered vaginally and those who had a cesarean delivery (CD) for arrest of descent. RESULTS: Of the 191 women who met the inclusion criteria, 62 (32.5%) delivered spontaneously, 96 (50.2%) had a vacuum extraction (VE) and 33 (17.3%) had a CD. The mean AOP was wider among women who had VD (spontaneous or VE) compared to those who had CD (153° ± 19 vs. 133° ± 17, p < 0.001). Wider AOPs were associated with higher rates of VD and an AOP ≥ 127° was associated with a VD rate of 88.6% (148/167). Among the 87 women who had more than one AOP measurement, the mean AOP change per hour was higher in the VD group than in the CD group (15.1° ± 11.4° vs. 6.2° ± 6.3°, p < 0.001). CONCLUSION: Ultrasound-assessed fetal head station in nulliparous women with a protracted second stage of labor can be an accurate and objective additive tool in predicting the mode and interval time to delivery in real-life clinical practice.

Asynclitism and Its Ultrasonographic Rediscovery in Labor Room to Date: A Systematic Review.

Asynclitism, the most feared malposition of the fetal head during labor, still represents to date an unresolved field of interest, remaining one of the most common causes of prolonged or obstructed labor, dystocia, assisted delivery, and cesarean section. Traditionally asynclitism is diagnosed by vaginal examination, which is, however, burdened by a high grade of bias. On the contrary, the recent scientific evidence highly suggests the use of intrapartum ultrasonography, which would be more accurate and reliable when compared to the vaginal examination for malposition assessment. The early detection and characterization of asynclitism by intrapartum ultrasound would become a valid tool for intrapartum evaluation. In this way, it will be possible for physicians to opt for the safest way of delivery according to an accurate definition of the fetal head position and station, avoiding unnecessary operative procedures and medication while improving fetal and maternal outcomes. This review re-evaluated the literature of the last 30 years on asynclitism, focusing on the progressive imposition of ultrasound as an intrapartum diagnostic tool. All the evidence emerging from the literature is presented and evaluated from our point of view, describing the most employed technique and considering the future implication of the progressive worldwide consolidation of asynclitism and ultrasound.