I. Cataneo

Risk of 22q11.2 deletion in fetuses with right aortic arch and without intracardiac anomalies

To assess the risk of 22q11.2 deletion in fetuses with a prenatal diagnosis of right aortic arch without intracardiac anomalies (RAA‐no ICA).

Intrapartum Ultrasound to Differentiate Flexion and Deflexion in Occipitoposterior Rotation

Objective: To evaluate the ability of intrapartum ultrasound to differentiate occipitoposterior (OP) rotation with normal flexion of the head from deflexion, to compare the accuracy of ultrasound with the digital examination, and to assess the outcome of labor according to the type of presentation. Patients and Methods: A retrospective study of patients with abnormal labor because of either prolongation and/or abnormal cardiotocography and OP rotation who underwent intrapartum sonography. Results: Normal flexion was inferred in 36/42 cases by a longitudinal sonographic view of the fetal face demonstrating the chin approaching the chest. In the remaining 6, deflexion was diagnosed by visualizing the chin separate and distant from the chest. In 3 of these cases, the orbits were at the same level of the pubis suggesting brow presentation. In the remaining 3 cases, the orbits were above the pubis, and sinciput presentation was inferred. Head deflexion was diagnosed more accurately with ultrasound than clinically and always required a cesarean section versus 36% of cases with OP flexed presentation (p = 0.0052). Conclusions: Fetuses with abnormal labor and OP rotation had deflexed presentations in 14% of cases and were never delivered vaginally. Sonography was far more accurate than the digital examination.

Agreement between two 3D ultrasound techniques for the assessment of the subpubic arch angle.

Abstract Objectives: To assess the reliability of a new three-dimensional (3D) ultrasound technique for the measurement of the subpubic arch angle (SPA) and the agreement between two contrast-enhancing 3D ultrasound techniques. Methods: We acquired two static 3D transperineal volumes from 72 nulliparous women using two ultrasound machines equipped with two different 3D contrast enhancement and linear reconstruction softwares: 1. Oblique View Extended Imaging with HD-Volume Imaging (OVIX-HDVI™), Samsung; 2. Omniview with Volume Contrast Imaging (Omniview-VCI™), GE Healthcare. An operator measured SPA once by OVIX-HDVI, and twice by Omniview-VCI, while another operator measured SPA once by Omniview-VCI. We evaluated intra- and inter-observer reproducibility of Omniview-VCI and intermethod agreement. Reproducibility and intermethod agreement were studied by means of intraclass correlation coefficient (ICC) and Bland–Altman method. Results: Omniview-VCI SPA measurements showed excellent intraobserver and interobserver reproducibility (ICC 0.970; 95% C.I. 0.952 to 0.981, 0.932; 95% C.I. 0.893 to 0.957, respectively). Furthermore, Omniview VCI SPA measurements demonstrated excellent agreement with those performed by OVIX-HDVI technique (ICC 0.943; 95 C.I. 0.911 to 0.964). No systematic difference was found in any of the reliability studies. Conclusions: OmniView-VCI is a reliable method for SPA assessment. Both OmniView-VCI and OVIX-HDVI can be used interchangeably for SPA measurement.

Three-dimensional/four-dimensional transperineal ultrasound: clinical utility and future prospects

During the last decade, there has been a huge advancement in the use of transperineal ultrasound (TPU) in the field of obstetrics and gynecology. Its main applications in obstetrics include the monitoring of fetal progression in labor and recently the assessment of maternal pelvic dimensions, whereas in gynecology, TPU is at present widely used for the evaluation of the female pelvic floor, opening new boundaries for the assessment of pelvic floor disorders. The association of volumetric three-dimensional techniques has largely contributed to the remarkable progress that has occurred in the use of TPU. The aim of this paper is to offer an overview of the advantages, challenges and future perspectives of the use of TPU for women’s imaging.

Fundal pressure in second stage of labor (Kristeller maneuver) is associated with higher risk of levator ani muscle avulsion

To investigate the association between application of fundal pressure during the second stage of labor (Kristeller maneuver) and the risk of levator ani muscle (LAM) injury.

OC13.06: Dynamic changes of angle of progression at term and the mode of delivery

was considered. The mode of delivery was evaluated using receiver-operating characteristics curves and descriptive statistics. Results: 222 women were included in the study. The head-perineum distance was associated with spontaneous delivery with area under the curve 83% (95% CI 77–89%) and was associated with Caesarean with area under the curve 83% (95% CI 74–92%). In women with head-perineum distance ≤35mm, 7/181 (3.9%) were delivered by Caesarean versus 9/41 (22.0%) in women with head-perineum distance >35 mm (p <0.01). Ultrasound assessed position was occiput anterior (OA) in 73%. Only 3/138 (2.2%) of fetuses in OA position and head-perineum distance ≤35 mm versus 6/17 (35.3%) with non-OA position and head-perineum distance >35 mm were delivered by Caesarean. Conclusions: Ultrasound has the potential to predict mode of delivery in women with prolonged second stage of labour.

OP28.09: The levator-urethral gap measurement: tomographic ultrasound imaging (TUI) versus Omniview-volume contrast imaging (VCI)

pelvic organ mobility and hiatal dimensions of East Asians and Caucasians presenting with symptomatic pelvic organ prolapse. Methods: We undertook offline analysis of 4D ultrasound volume data obtained from women who presented to tertiary urogynecology clinics with symptomatic pelvic organ prolapse from 2011-12 in Hong Kong and 2015-16 in Sydney. Women with previous hysterectomy and/ or incontinence or prolapse surgery were excluded. Volume acquisition was performed using Voluson systems using an identical methodology. On post-processing, pelvic organ descent and hiatal dimensions were assessed on Valsalva manoeuvre. Levator muscle avulsion was assessed in volumes obtained on pelvic floor muscle contraction. Results: A total of 431 datasets were reviewed: 225 of Asian and 206 of Caucasian women. Pelvic organ descent and hiatal dimensions are shown in table 1. Asian women seem more likely to present with bladder and uterine prolapse while rectocele is more prevalent in Caucasians. All hiatal dimensions on Valsalva were larger in Caucasian women. The prevalence of levator avulsion was similar in both groups (p=0.38). Conclusions: There were substantial differences in pelvic organ descent and hiatal dimensions between Asian and Caucasian women presenting with symptomatic prolapse, the most obvious being much higher uterine mobility in Asians.

P04.08: Neonatal head circumference is not a risk factor for levator ani avulsion

diagnosed slow progress in labour after 45 minutes of active pushing and a vacuum extraction was considered. The fetal head position was determined with transabdominal or transperineal ultrasound before vacuum extraction. They were categorised in occiput anterior (OA), occiput transverse (OT) and occiput posterior (OP). Results: 150 vacuum extractions were performed. Before vacuum extraction 108 (76%) fetuses were in an OA position, 15 (11%) were in an OT position and 19 (13%) in an OP position. In 8 cases position before vacuum was not recorded. Of the fetuses in OA position 99% were delivered by vacuum extraction in OA position and 1% rotated into OP position. 80% of the fetuses in OT position rotated into OA position and 20% into OP position. Of the fetuses in OP position 69% rotated into OA position and 31% stayed in OP position at delivery. Conclusions: The majority of fetuses in OT and OP position before vacuum extraction because of prolonged second stage of labour rotate into OA position during vacuum extraction.

OC20.02: Dynamic assessment of pelvic hiatal dimensions at term and the mode of delivery in low‐risk nulliparous women

Objectives: To evaluate the diagnostic benefit of using three-dimensional colour imaging with post-processing Crystal Vue Flow (Samsung Medison, Republic of Korea) software to assess 6 cases of suspected abnormally invasive placenta (AIP). Methods: Six patients with suspected major placenta previa were evaluated. 83% of the patients had 1 or more previous Caesarean sections. B-mode transabdominal sonography using a WS80A Elite system was performed and colour Doppler was then applied to map the vascularisation of the uterine serosa-bladder interface. 3D colour volumes were obtained from a sagittal section of the uterus bisecting a partially full bladder and processed using Crystal Vue Flow. Results: In one case of placenta previa without suspicion of AIP, Crystal Vue Flow revealed a ‘tramline’ like appearance of the intact bladder mucosa and uterine myometrial interface (Fig 1,2). In the other 5 cases there was abnormal vascularity at the uterovesical fold with partial obliteration of the ‘tramlines’ on the rendered volume, suggestive of an AIP (Fig 3,4). The degree of vascular invasion and obliteration of the ‘tramline’ sign appeared strongly indicative of the severity of AIP. The ultrasound appearances were corroborated on MRI and at delivery the diagnosis of AIP was consistent with antenatal sonographic findings. Conclusions: Crystal Vue Flow imaging may add valuable information when diagnosing and determining the type of AIP. Greater diagnostic certainty of AIP will allow improved multi-disciplinary input and decision-making regarding timing and place of delivery and will enable improved patient counselling.

OC20.01: Larger pelvic hiatal dimensions at term are associated with shorter labour durations in low‐risk nulliparous women

Objectives: To evaluate the diagnostic benefit of using three-dimensional colour imaging with post-processing Crystal Vue Flow (Samsung Medison, Republic of Korea) software to assess 6 cases of suspected abnormally invasive placenta (AIP). Methods: Six patients with suspected major placenta previa were evaluated. 83% of the patients had 1 or more previous Caesarean sections. B-mode transabdominal sonography using a WS80A Elite system was performed and colour Doppler was then applied to map the vascularisation of the uterine serosa-bladder interface. 3D colour volumes were obtained from a sagittal section of the uterus bisecting a partially full bladder and processed using Crystal Vue Flow. Results: In one case of placenta previa without suspicion of AIP, Crystal Vue Flow revealed a ‘tramline’ like appearance of the intact bladder mucosa and uterine myometrial interface (Fig 1,2). In the other 5 cases there was abnormal vascularity at the uterovesical fold with partial obliteration of the ‘tramlines’ on the rendered volume, suggestive of an AIP (Fig 3,4). The degree of vascular invasion and obliteration of the ‘tramline’ sign appeared strongly indicative of the severity of AIP. The ultrasound appearances were corroborated on MRI and at delivery the diagnosis of AIP was consistent with antenatal sonographic findings. Conclusions: Crystal Vue Flow imaging may add valuable information when diagnosing and determining the type of AIP. Greater diagnostic certainty of AIP will allow improved multi-disciplinary input and decision-making regarding timing and place of delivery and will enable improved patient counselling.