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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

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. Synopsis: Utilization intrapartum ultrasound to qualify the effect of asynclitism on delivery outcomes. [ABSTRACT FROM AUTHOR]

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.

The investigation studied the enkephalinergic neuro fibers (En) contained in the Lower Uterine Segment (LUS) during the prolonged dystocic labor (PDL) with Labor Neuraxial Analgesia (LNA). PDL is generally caused by fetal head malpositions in the Occiput Posterior Position (OPP), Persistent Occiput Posterior Position (POPP), in a transverse position (OTP), and asynclitism (A), and it is detected by Intrapartum Ultrasonography (IU). The En were detected in the LUS samples picked up during cesarean section (CS) of 38 patients undergoing urgent CS in PDL, compared to 37 patients submitted to elective CS. Results were statistically evaluated to understand the differences in En morphological analysis by scanning electron microscopy (SEM) and by fluorescence microscopy (FM). The LUS samples analysis showed an important reduction in En in LUS of CS for the PDL group, in comparison with the elective CS group. The LUS overdistension, by fetal head malpositions (OPP, OTP, A) and malrotations, lead to dystocia, modification of vascularization, and En reduction. The En reduction in PDL suggests that drugs used during the LNA, usually local anesthetics and opioids, cannot control the "dystocic pain", that differs from normal labor pain. The IU administration in labor and the consequent diagnosis of dystocia suggest stopping the numerous and ineffective top-up drug administration during LNA, and to shift the labor to operative vaginal delivery or CS. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Asynclitism is malposition and malpresentation of the head in the pelvis. It is shown that asynclitism during the configuration (molding) of the head leads to an uneven distribution of the tension forces of the tentorium cerebelli (TC) and to its one-sided ruptures, mainly in the left half. It is indicated that with asynclitism larger more than 15 mm (moderate degree of asynclitism), the risk of birth trauma to the skull and brain increases. It was shown that not only severe degree of asynclitism, but also a moderate degree are pathological due to possible complications. The data on the sonographic diagnosis of asynclitism are presented. The negative effects of vacuum extraction (VE), the forceps application are considered. The mechanism of subaponeurotic hemorrhages is described. The importance of timely asynclitism diagnosis in labor to prevent its complication is shown. The cesarean section is practiced as extreme solution to the problem. The widespread use of sonography for the asynclitism diagnosis will prevent the birth trauma and reduce the incidence of mobility and mortality of the children and mother. [ABSTRACT FROM AUTHOR]

The investigation studied the enkephalinergic neuro fibers (En) contained in the Lower Uterine Segment (LUS) during the prolonged dystocic labor (PDL) with Labor Neuraxial Analgesia (LNA). PDL is generally caused by fetal head malpositions in the Occiput Posterior Position (OPP), Persistent Occiput Posterior Position (POPP), in a transverse position (OTP), and asynclitism (A), and it is detected by Intrapartum Ultrasonography (IU). The En were detected in the LUS samples picked up during cesarean section (CS) of 38 patients undergoing urgent CS in PDL, compared to 37 patients submitted to elective CS. Results were statistically evaluated to understand the differences in En morphological analysis by scanning electron microscopy (SEM) and by fluorescence microscopy (FM). The LUS samples analysis showed an important reduction in En in LUS of CS for the PDL group, in comparison with the elective CS group. The LUS overdistension, by fetal head malpositions (OPP, OTP, A) and malrotations, lead to dystocia, modification of vascularization, and En reduction. The En reduction in PDL suggests that drugs used during the LNA, usually local anesthetics and opioids, cannot control the “dystocic pain”, that differs from normal labor pain. The IU administration in labor and the consequent diagnosis of dystocia suggest stopping the numerous and ineffective top-up drug administration during LNA, and to shift the labor to operative vaginal delivery or CS.

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.

Fetal malpresentation, malposition, and asynclitism are among the most common determinants of a protracted active phase of labor, arrest of dilatation during the first stage, and arrest of descent in the second stage. The diagnosis of these conditions is traditionally based on vaginal examination, which is subjective and poorly reproducible. Intrapartum sonography has been demonstrated to yield higher accuracy than vaginal examination in characterizing fetal malposition, and some guidelines endorse its use for the verification of the occiput position before performing an instrumental delivery. It is also useful for the objective diagnosis of the malpresentation or asynclitism of the fetal head. According to our experience, the sonographic assessment of the head position in labor is simple to perform also for clinicians with basic ultrasound skills, whereas the assessment of malpresentation and asynclitism warrants a higher level of expertise. When clinically appropriate, the fetal occiput position can be easily ascertained using transabdominal sonography combining the axial and the sagittal planes. With the transducer positioned on the maternal suprapubic region, the fetal head can be visualized, and landmarks including the fetal orbits, the midline, and the occiput itself with the cerebellum and the cervical spine (depending on the type of fetal position) can be demonstrated below the probe. Sinciput, brow, and face represent the 3 "classical" variants of cephalic malpresentation and are characterized by a progressively increasing degree of deflexion from vertex presentation. Transabdominal sonography has been recently suggested for the objective assessment of the fetal head attitude when a cephalic malpresentation is clinically suspected. Fetal attitude can be evaluated on the sagittal plane with either a subjective or an objective approach. Two different sonographic parameters such as the occiput-spine angle and the chin-chest angle have been recently described to quantify the degree of flexion in fetuses in non-occiput-posterior or occiput-posterior position, respectively. Finally, although clinical examination still represents the mainstay of diagnosis of asynclitism, the use of intrapartum sonography has been shown to confirm the digital findings. The sonographic diagnosis of asynclitism can be achieved in expert hands using a combination of transabdominal and transperineal sonography. At suprapubic sonography on the axial plane only, 1 orbit can be visualized (squint sign) while the sagittal suture appears anteriorly (posterior asynclitism) or posteriorly (anterior asynclitism) displaced. Eventually the transperineal approach does not allow the visualization of the cerebral midline on the axial plane if the probe is perpendicular to the fourchette. In this expert review we summarize the indications, technique, and clinical role of intrapartum sonographic evaluation of fetal head position and attitude., (Copyright © 2022 Elsevier Inc. All rights reserved.)

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

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., Competing Interests: All the authors declare that they have not conflicts of interest., (© 2024 The Authors.)

OBJECTIVE: Intrapartum ultrasound (IU) is a valid support to obstetric management of fetal head progression in the second stage of labor in nulliparous with neuraxial labor analgesia (NLA). Nulliparous with NLA may have a prolonged the second stage of labor. The aim of this literature review was to evaluate the mode of delivery, as well as maternal and fetal morbidities associated with missed progression of fetal head detected with IU in the second stage of labor in nulliparous women with NLA. MATERIALS AND METHODS: The literature review was performed using PubMed, Cochrane, Medline, EMBASE, Scopus, Google Scholar and book chapters searches to identify relevant articles from 2001 to 2019, evaluating the mode of delivery and morbidities of the second stage of labor. Search terms used were "Intrapartum ultrasound", "dystocia", "prolonged labor", "neuraxial analgesia", "persistent occiput posterior position", "asynclitism", "second stage of labor", "medico- legal aftermath". Prolonged second stage was defined as three hours and more. Retrospective case series of women with prolonged second stage of labor with NLA were identified. The primary outcome was the incidence of operative vaginal delivery (OVD) and cesarean delivery (CS). RESULTS: The use of NLA may determine a prolonged second stage of labor (PSSL). IU when compared to the traditional vaginal digital examination (VDE) demonstrated the highest degree of diagnostic accuracy. CONCLUSIONS: The use of IU during NLA can aid in the diagnosis of fetal head progression, station or malposition and malrotation, alerts obstetrician on the possibility of dystocic labor, indicating to stop the drug administration in NLA and shift to OVD or CS. Extending the second stage of labor beyond current American College of Obstetricians and Gynecologists (ACOG) recommendations is beneficial. The ISUOG guidelines recommended the clinical application of IU to diagnose the persistent occiput posterior position (POPP) and asynclitism (A) in dystocic labor and produce photographic evidence of the case. Maternal and neonatal complications, medicolegal consequences and litigation can decrease if the IU device is used as good practice. [ABSTRACT FROM AUTHOR]

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

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

Asynclitism is defined as the “oblique malpresentation of the fetal head in labor”. Asynclitism is a clinical diagnosis that may be difficult to make; it may be found during vaginal examination. It is significant because it may cause failure of progress operative or cesarean delivery. We reviewed all literature for asynclitism by performing an extensive electronic search of studies from 1959 to 2013. All studies were first reviewed by a single author and discussed with co-authors. The following studies were identified: 8 book chapters, 14 studies on asynclitism alone and 10 papers on both fetal occiput posterior position and asynclitism. The fetal head in a laboring patient may be associated with some degree of asynclitism; this is seen as usual way of the fetal head to adjust to maternal pelvic diameters. However, marked asynclitism is often detected in presence of a co-existing fetal head malposition, especially the transverse and occipital posterior positions. Digital diagnosis of asynclitism is enhanced by intrapartum ultrasound with transabdominal or transperineal approach. The accurate diagnosis of asynclitism, in an objective way, may provide a better assessment of the fetal head position that will help in the correct application of vacuum and forceps, allowing the prevention of unnecessary cesarean deliveries. [ABSTRACT FROM PUBLISHER]

Objective: The primary goal of this study was to determine the ultrasonographic signs of asynclitic and transverse head positioning. In addition, we compared the performance of intrapartum ultrasound to vaginal digital examination. Material & Methods: 150 women were evaluated by 2D transabdominal and translabial ultrasound (US) to detect the asynclitic and deep transverse positions. Transvaginal sterile digital examinations were performed immediately after each intrapartum US assessments, the examinations were repeated at intervals of 45-90 minutes. Examiners were blinded to each other's findings (clinical or sonographic). Data were reviewed and analyzed by an independent reviewer. Results: The efficacy of digital examination was significantly lower than US evaluation for the detection of either transverse position or asynclitism. The most frequent transverse position was the left one, while the most frequent asynclitism was the anterior one. Conclusions: Digital pelvic examination for detection of fetal head transverse position during labor is inferior to US, especially in the deep transverse positioning, where caput succedaneum occurs and reduces the diagnostic accuracy of vaginal digital examination. The US examination leads to early detection of persistent transverse position allowing for earlier timing and optimal technique for the operative vaginal delivery. We describe two signs for diagnosing asynclitism. The 'squint sign' and the 'sunset of thalamus and cerebellum signs' are two simple US signs allowing detection of anterior and posterior asynclitism. [ABSTRACT FROM AUTHOR]

Purpose: To investigate if early epidural analgesia can influence fetal head engagement into the pelvis and if it can increase the rate of transverse and asynclitic position during labour. Materials and Methods: 195 women with combined spinal-epidural analgesia (CSE) or without neuraxial analgesia were studied. CSE was performed using a mixture of ropivacaine 0.02% with 0.3 µg/ml of sufentanil administered in the spinal space. Maintenance of analgesia was managed with intermittent epidural administration of 10-15 ml of ropivacaine (0.07%-0.10%) mixed with 0.5 µg/ml of sufentanil, based on the stage of labour and the degree of pain. 2D transabdominal ultrasound (US) was used. Serial transabdominal US examinations were performed at 45-90 min intervals to detect transverse and asynclitic positions, using the following signs: squint sign, sunset thalamus and cerebellum signs that best details the fetal head station. After delivery, the complete set of clinical and US data obtained by each examination were recorded and compared in women with and without labour analgesia. Data were examined by independent reviewers. Results: There was no difference in obstetric outcome between women in whom CSE had been used and those who did not request analgesia during labour (p>0.05). Conclusions: Epidural analgesia initiated early during labour and using low doses does not increase the rate of dystocic labors. Transverse fetal head positioning with anterior or posterior asynclitism does not seem to be promoted by drug or technique-related mechanisms, but rather should be the consequence of cephalopelvic disproportion. [ABSTRACT FROM AUTHOR]

Fetuses with malpresentation and malposition during labor represent important clinical challenges. Women with fetuses presenting with malpresentation or malposition are at risk of increased perinatal complications, such as cesarean delivery, failure of operative vaginal delivery, neonatal acidemia, and neonatal intensive care admission. Intrapartum ultrasound has been found to be more reliable than digital examination in assessing malpresentation and malposition. The use of intrapartum ultrasound to assess fetal position and presentation, in addition to fetal attitude, to predict and aid in decision making regarding delivery can help in improving management decision making. Cephalic malpresentation and malposition is a unique subset of fetal orientation and can benefit from intrapartum ultrasound identification and assessment for delivery., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Fetal head asynclitism may affect labor progress, increase the need for obstetrical intervention, and even be associated with difficult or failed instrumental delivery. However, there is limited evidence on the true prevalence and associations of asynclitism when diagnosed by transperineal ultrasound in the second stage of labor., Objective: This study aimed to examine the prevalence and outcome of asynclitism in the second stage of labor in a regional hospital in Hong Kong., Study Design: This is a prospective cohort study involving 92 term nulliparous women with singleton pregnancy in the second stage of labor, recruited from December 2019 to December 2020. Transperineal ultrasound was performed and asynclitism was diagnosed if there was asymmetry of intracranial structures on the transverse plane. To assess the fetal head station, the head perineum distance was measured at rest and on pushing, and the mode of delivery was recorded. Relationship between asynclitism and fetal head position, and between head perineum distance and the mode of delivery, were evaluated with chi-squared tests and Mann-Whitney U tests., Results: The prevalence of asynclitism was 15% (14 of 92), of which 12 were anterior asynclitism and 2 were posterior asynclitism. The prevalence of asynclitism was less common in occiput anterior compared with nonocciput anterior position (6.7% vs 53%, P<.01). Women with asynclitism were associated with smaller delta head perineum distance (head perineum distance at rest minus that at pushing) than women without asynclitism (median [interquartile range], 0.68 cm [0.85 cm] vs 0.91 cm [0.71 cm]; P=.01). Eventually, there was a trend of more operative deliveries in women with asynclitism (43%, or 6 of 14 women) than in women without asynclitism (27%, or 21 of 78 women), although this difference was not statistically significant (P=.22)., Conclusion: The prevalence of asynclitism at transperineal ultrasound was rather common in nulliparous women at second stage of labor and seemed more commonly associated with nonocciput anterior position., (Copyright © 2021 Elsevier Inc. All rights reserved.)