The August issue of Ultrasound in Obstetrics & Gynecology includes an updated cohort study and meta-analysis on cell-free DNA testing in screening for trisomies in twins, a study longitudinally evaluating motor function in prenatally vs postnatally repaired open neural tube defect cases, a study on cervical electrical impedance spectroscopy to predict spontaneous preterm delivery in asymptomatic women, a study on the association between vaginal birth after Cesarean section and levator ani muscle avulsion, and newly updated ISUOG Practice Guidelines on the use of Doppler velocimetry in obstetrics.

Please see below a selection of articles from the August issue of the Journal chosen specially by the UOG team. To view all UOG content, become an ISUOG member today or login and upgrade.

Cell-free DNA testing of maternal blood in screening for trisomies in twin pregnancy: updated cohort study at 10–14 weeks and meta-analysis

In contrast to singleton pregnancy, data on cell-free DNA (cfDNA) testing of maternal blood for trisomies 21, 18 and 13 in twin pregnancy are scant. In order to expand the limited knowledge on cfDNA testing in twins, Judah et al. updated the data from The Fetal Medicine Foundation (FMF) on prospective first-trimester screening and those identified in a systematic review of the literature. It was found that, in twin pregnancy, the reported detection rate of trisomy 21 by cfDNA testing is high, but lower than that in singleton pregnancy, whereas the false-positive rate appears to be equally low. The number of cases of trisomy 18 and more so trisomy 13 was too small for accurate assessment of the predictive performance of the cfDNA test. The authors emphasize that, if cfDNA testing is adopted as a first-line method of screening for trisomy in twin pregnancy, it is still imperative that women should be offered an 11–14-week scan to determine gestational age, chorionicity, whether the fetuses are alive and if there is increased nuchal translucency thickness or major defects that would merit invasive testing.

Longitudinal evaluation of motor function in patients who underwent prenatal or postnatal neural tube defect repair

Although it is thought that prenatal open neural tube defect (ONTD) repair improves motor function, there is a gap in knowledge in identifying which fetuses will have optimal motor function after birth. Corroenne et al. compared motor function and its evolution between pre- and postnatally repaired ONTD cases from mid-gestation to 12 months of age. Prenatal repair was found to prevent the deterioration of lower-extremity motor function based on in-utero ultrasound evaluation and postnatal neurological examinations. ONTD cases that underwent postnatal repair started showing worse motor function at the end of the third trimester, which persisted after birth and at 12 months of age. The authors conclude that prenatal ultrasound assessment of motor function should be considered as an important tool for the assessment of patients with ONTD.

Value of cervical electrical impedance spectroscopy to predict spontaneous preterm delivery in asymptomatic women: the ECCLIPPx prospective cohort study

Prevention of preterm birth (PTB) remains limited by the modest accuracy of prediction methods, namely transvaginal ultrasound (TVS) cervical length (CL) measurement and quantitative cervicovaginal fetal fibronectin (FFN) estimation. Electrical impedance spectroscopy (EIS) non-invasively quantifies cervical tissue impedance to the passage of a small electrical current and has been demonstrated previously to be able to detect prelabor cervical remodeling changes. Anumba et al. compared the accuracy of cervical EIS-based prediction of spontaneous PTB with that of prediction using TVS-CL and FFN in asymptomatic women in the mid-trimester. It was found that cervical EIS can predict spontaneous PTB in asymptomatic women as a standalone test as well as improve current risk-assessment approaches.

Vaginal birth after Cesarean section and levator ani avulsion: a case–control study

Although vaginal birth after Cesarean section (VBAC) is an extensively studied subject, to date, few studies have focused on pelvic floor trauma after this mode of birth and none of them studied the risk of levator ani muscle (LAM) avulsion. It has been postulated that the combination of a vaginally nulliparous pelvic floor, a larger fetus and more powerful uterine contractility may result in an increased likelihood of pelvic floor trauma following VBAC. Paymova et al. explored the risk of LAM avulsion and enlargement of the levator hiatus following VBAC in comparison with vaginal delivery in primiparous women. VBAC was found to be associated with a significantly higher rate of LAM avulsion than is vaginal birth in nulliparous women, and the difference was significant even after controlling for age and BMI.

ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics

Newly updated ISUOG Practice Guidelines describe how to perform Doppler ultrasonography of the fetoplacental circulation, including pulsed Doppler ultrasound and its different modalities: spectral Doppler, color flow mapping and power Doppler. The guidelines cover what equipment is needed, basic technical aspects, how to optimize acquisition of the Doppler waveforms, the appropriate technique for obtaining uterine artery, umbilical artery, fetal middle cerebral artery and fetal ductus venosus Doppler waveforms, calculation of the cerebroplacental and umbilicocerebral ratios, and which Doppler indices should be used.

Coming up next month…

  • A study on the short-term outcome of pregnant women vaccinated by the Pfizer/BioNTech COVID-19 vaccine. Preview the Accepted Article.
  • A study on the combination of Proactive Molecular Risk Classifier for Endometrial cancer (ProMisE) with sonographic and demographic characteristics in the preoperative prediction of tumor progression in endometrial cancer. Preview the Accepted Article.
  • A study on the impact of crown–rump length measurement errors on assessment of fetal growth. Preview the Accepted Article.