Ultrasound in labor: clinical practice guideline and recommendation by the WAPM-World Association of Perinatal Medicine and the PMF-Perinatal Medicine Foundation.

This recommendation document follows the mission of the World Association of Perinatal Medicine in collaboration with the Perinatal Medicine Foundation. We aim to bring together groups and individuals throughout the world for standardization to implement the ultrasound evaluation in labor ward and improve the clinical management of labor. Ultrasound in labor can be performed using a transabdominal or a transperineal approach depending upon which parameters are being assessed. During transabdominal imaging, fetal anatomy, presentation, liquor volume, and placental localization can be determined. The transperineal images depict images of the fetal head in which calculations to determine a proposed fetal head station can be made.

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.

Intrapartum translabial ultrasound demonstration of face presentation during first stage of labor.

We report an unusual case in which sonographic diagnosis of face presentation was made by translabial ultrasound examination during the first stage of labor. In a multigravida, induction of labor was performed at 39 weeks' gestation for suspected small-for-gestational age. The diagnosis of face presentation was confirmed by the use of intrapartum translabial ultrasound examination. In face presentation, the orbits and nasal bridge are shown in the center of the presenting part at the mid-sagittal plane. Emergency cesarean delivery was performed for labor dystocia. Here we discuss the merits and limitations of transabdominal, transvaginal and translabial ultrasound examinations in assisting clinical diagnosis of non-vertex malpresentation. We propose the use of intrapartum translabial scan in documentation, counseling and education in case of unusual non-vertex malpresentation.

Asynclitism in the second stage of labor: prevalence, associations, and outcome.

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.

Measuring angle of progression by transperineal ultrasonography to predict successful instrumental and cesarean deliveries during prolonged second stage of labor.

OBJECTIVE: To compare the angle of progression (AoP) measured by transperineal ultrasonography before indicating an instrumental delivery or cesarean delivery. METHODS: A prospective observational study was conducted among women with singleton term pregnancies with prolonged second stage of labor at Kwong Wah Hospital, Hong Kong, China, between May 16, 2011, and May 25, 2016. Transabdominal and transperineal ultrasonography were performed to determine fetal head position and AoP, respectively, both at rest and during uterine contraction with pushing. Mode of delivery was decided after vaginal examination without relying on ultrasonography. RESULTS: Of 143 women, 116 underwent successful instrumental delivery and 27 underwent cesarean delivery. Median AoP was 153.0° in the instrumental group versus 139.0° in the cesarean group at rest (P<0.001), and 182.5° in the instrumental group versus 156.5° in the cesarean group during contraction (P<0.001). The best predictive cutoff AoP for successful instrumental delivery was 138.7° at rest (sensitivity 86.2%, specificity 51.9%) and 160.9° during contraction (sensitivity 87.1%, specificity 74.1%). No between-group differences in AoP were found for ease of vacuum extraction at rest (P=0.457) or during contraction with pushing (P=0.095). CONCLUSION: The AoP predicted approximately 80% of successful instrumental deliveries performed for prolonged second stage of labor.

Use of second-line therapies for management of massive primary postpartum hemorrhage.

OBJECTIVE: To determine rates of use and success of second-line therapies for massive primary postpartum hemorrhage (PPH). METHODS: A retrospective cohort study was conducted among 91 women who gave birth at Kwong Wah Hospital, Hong Kong, between January 1, 2006, and December 31, 2011. Inclusion criteria were gestational age of at least 24 weeks and massive PPH (defined as blood loss ≥1500 mL within 24 hours after birth). Second-line therapies assessed were uterine compression sutures, uterine artery embolization, and balloon tamponade after failure of uterine massage and uterotonic agents to stop bleeding. RESULTS: The rate of massive PPH was 2.65 per 1000 births. Second-line therapies were used among 42 women with PPH, equivalent to a rate of 1.23 per 1000 births. Only 21.4% of the women who received second-line therapies required rescue hysterectomy. A rising trend was observed for the use of second-line therapies, whereas the incidence of rescue hysterectomy and estimated blood loss were found to concomitantly decrease. CONCLUSION: Increasing use of second-line therapies among women with massive PPH was associated with a decreasing trend for rescue hysterectomy. Obstetricians should, therefore, consider all available interventions to stop PPH, including early use of second-line options.

Pregnancy outcome of a patient with atypical polypoid adenomyoma.

OBJECTIVE: Detailed description and follow-up of a patient with atypical polypoid adenomyoma and infertility, from investigation until delivery of a healthy baby. DESIGN: Case report. SETTING: Tertiary infertility center. PATIENT(S): A patient suffering from persistent APA and infertility. INTERVENTION(S): Danggui (Angelica sinensis) and low-dose aspirin. MAIN OUTCOME MEASURE(S): Pregnancy and live birth. RESULT(S): Conception after Danggui but intrauterine death at 25 weeks. Successful live birth after Danggui plus low-dose aspirin. CONCLUSION(S): Danggui corrected atypical polypoid adenomyoma and led to pregnancy twice in the same patient. Low-dose aspirin may improve the circulation in the placental bed and lead to live birth.