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Objective: This study aimed to assess the efficacy of sonographic assessment of fetal occiput position before operative vaginal delivery to decrease the number of failed operative vaginal deliveries.Data Sources: The search was conducted in MEDLINE, Embase, Web of Science, Scopus, ClinicalTrial.gov, Ovid, and Cochrane Library as electronic databases from the inception of each database to April 2021. No restrictions for language or geographic location were applied.Study Eligibility Criteria: Selection criteria included randomized controlled trails of pregnant women randomized to either sonographic or clinical digital diagnosis of fetal occiput position during the second stage of labor before operative vaginal delivery.Methods: The primary outcome was failed operative vaginal delivery, defined as a failed fetal operative vaginal delivery (vacuum or forceps) extraction requiring a cesarean delivery or forceps after failed vacuum. The summary measures were reported as relative risks or as mean differences with 95% confidence intervals using the random effects model of DerSimonian and Laird. An I2 (Higgins I2) >0% was used to identify heterogeneity.Results: A total of 4 randomized controlled trials including 1007 women with singleton, term, cephalic fetuses randomized to either the sonographic (n=484) or clinical digital (n=523) diagnosis of occiput position during the second stage of labor before operative vaginal delivery were included. Before operative vaginal delivery, fetal occiput position was diagnosed as anterior in 63.5% of the sonographic diagnosis group vs 69.5% in the clinical digital diagnosis group (P=.04). There was no significant difference in the rate of failed operative vaginal deliveries between the sonographic and clinical diagnosis of occiput position groups (9.9% vs 8.2%; relative risk, 1.14; 95% confidence interval, 0.77-1.68). Women randomized to sonographic diagnosis of occiput position had a significantly lower rate of occiput position discordance between the evaluation before operative vaginal delivery and the at birth evaluation when compared with those randomized to the clinical diagnosis group (2.3% vs 17.7%; relative risk, 0.16; 95% confidence interval, 0.04-0.74; P=.02). There were no significant differences in any of the other secondary obstetrical and perinatal outcomes assessed.Conclusion: Sonographic knowledge of occiput position before operative vaginal delivery does not seem to have an effect on the incidence of failed operative vaginal deliveries despite better sonographic accuracy in the occiput position diagnosis when compared with clinical assessment. Future studies should evaluate how a more accurate sonographic diagnosis of occiput position or other parameters can lead to a safer and more effective operative vaginal delivery technique. [ABSTRACT FROM AUTHOR]

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.)

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]

Objectives To determine the association between fetal position at onset of labor and mode of delivery, specifically left occipito-anterior (LOA) fetal position and spontaneous vaginal delivery (SVD). Methods All nulliparous women who were booked at the Birmingham Women's NHS Foundation Trust over an 18-month period from April 2007 to September 2008 with a singleton live fetus without structural anomalies at term gestation were invited to take part in the study. Women recruited to the study underwent a transabdominal ultrasound scan to determine fetal occiput position at the onset of labor. They were then followed up until birth to determine outcome. The primary outcome measure was mode of delivery, categorized into SVD, instrumental delivery and Cesarean section. Results Of 1647 eligible women, 1250 had valid scans at onset of labor; 155 of the 1250 (12.4%) had fetuses in the LOA position. Analysis showed no evidence of difference in odds ratio (OR) of SVD for fetuses in the LOA position compared with all other positions (OR 0.864 (95% CI, 0.617-1.209); P = 0.394). No difference remained with adjustment for confounding effects of variables known to influence mode of delivery (OR 0.837 (95% CI, 0.551-1.272); P = 0.405). No other occipital position showed significant association with SVD. There was no evidence of the LOA position being associated with Cesarean section, ventouse or forceps delivery. Conclusion There is no evidence of an association between the fetal LOA position at onset of labor and SVD. This finding challenges the conventional theory that LOA is the optimum fetal position at onset of labor, and suggests that antenatal practices encouraging adoption of the LOA position through maternal posturing are unnecessary. [ABSTRACT FROM AUTHOR]