To mark International Cesarean Awareness Month, the April issue of Ultrasound in Obstetrics & Gynecology includes a series of research papers and expert opinions on the topics of abnormally adherent placenta and Cesarean scar pregnancy. The issue also includes a study investigating predictors of fetal cerebral ischemic injury in monochorionic twin pregnancy complicated by spontaneous single intrauterine demise, a large prospective study reporting ophthalmic artery Doppler findings in non-hypertensive pregnancies with small-for-gestational-age or growth-restricted fetus, a multicenter study on the use of clinical phenotypes of small-for-gestational age for risk stratification and a short report demonstrating the positive impact of vaccination on maternal outcome during the Omicron wave of the COVID-19 pandemic.
Definition and sonographic reporting system for Cesarean scar pregnancy in early gestation: modified Delphi method
There is currently no uniform reporting system or sonographic evaluation guideline for Cesarean scar pregnancy (CSP). The Delphi study by Jordans et al., based on consensus among 16 experts in obstetric and gynecological sonography, provides guidance for ultrasound diagnosis, evaluation and reporting of CSP in early pregnancy. Basic and advanced standardized sonographic evaluation and reporting systems are described, providing recommendations for gynecologists and sonographers in identifying CSP in early pregnancy and a framework for experts to use during advanced evaluation of CSP. These recommendations should increase the awareness and recognition of CSP and improve outcome.
Prospective evaluation of impact of post-Cesarean section uterine scarring in perinatal diagnosis of placenta accreta spectrum disorder
Standardized ultrasound imaging and pathology protocols have recently been developed for the perinatal diagnosis of placenta accreta spectrum (PAS) disorders. Hussein et al. evaluated prospectively the effectiveness of these protocols in the prenatal diagnosis and postnatal examination of women presenting with a low-lying placenta/placenta previa and a history of multiple Cesarean deliveries. The study demonstrated that the lower uterine segment in the affected women shows extended remodeling due to scarring on both ultrasound examination and intraoperatively, independently of the presence of accreta villous tissue on microscopic examination. The authors emphasize the value of histological examination, which allows to differentiate between the anatomical changes due to scarring vs those associated with PAS, in improving diagnosis and management of PAS.
Diagnosis of placenta accreta spectrum in high-risk women using ultrasonography or magnetic resonance imaging: systematic review and meta-analysis
Imaging assessment can aid in the mitigation of complications associated with placenta accreta spectrum disorder (PAS). A systematic review and meta-analysis by De Oliveira Carniello et al. compared the performance of MRI and ultrasound in the diagnosis of PAS in high-risk women and demonstrated similar accuracy of the two modalities. Both sensitivity and specificity in the study were lower than expected, suggesting that a combination of techniques or imaging findings may be necessary to improve diagnostic performance and highlighting the need for further research. The authors suggest that, for the time being, the choice of the imaging technique should be based on the availability of equipment and expertise of the examiner.
Early imaging predictors of fetal cerebral ischemic injury in monochorionic twin pregnancy complicated by spontaneous single intrauterine death
Monochorionic twin pregnancy is associated with increased risk of single intrauterine death (sIUD) and subsequent development of brain injury in the surviving twin. A novel study by Shinar et al. investigated the predictors of cerebral injury in the surviving twin following sIUD. The study demonstrated that middle cerebral artery peak systolic velocity is associated with, but is a poor predictor of, this outcome. On the other hand, diffusion-weighted imaging (DWI) was demonstrated to be a valuable tool that can be used in addition to the gold standard T2-weighted MRI to help identify cerebral injury within 2 weeks after sIUD diagnosis. Although the decision regarding pregnancy continuation cannot be based solely on abnormal DWI in the acute phase, an early normal DWI-MRI scan can provide reassurance to parents.
Ophthalmic artery Doppler at 35–37 weeks’ gestation in pregnancies with small or growth-restricted fetuses
Few studies have assessed ophthalmic artery Doppler parameters in small-for-gestational-age (SGA) pregnancies. In a large, prospective study by Abdel Azim et al., women with SGA or growth-restricted fetuses in the absence of hypertensive disorders of pregnancy (HDP) underwent ophthalmic artery Doppler assessment in the third trimester. The findings of the study revealed that, compared with unaffected pregnancies, the SGA group had an increased ophthalmic artery peak systolic velocity (PSV) ratio, as well as increased mean arterial pressure and decreased serum concentration of placental growth factor. These changes were similar to those seen in HDP pregnancies, though they differed in magnitude and physiology. The study also demonstrated a linear, inverse association between PSV ratio and birth weight in non-HDP pregnancies, suggesting the presence of a continuous physiological relationship between fetal size and maternal cardiovascular response.
Clinical phenotypes for risk stratification in small-for-gestational-age fetuses
Small fetuses without chromosomal, structural and Doppler abnormalities are presumed to be constitutionally small-for-gestational age (SGA). However, these fetuses are at higher risk of poor perinatal outcome compared with appropriate-for-gestational-age cases. In a study of 17,631 singleton pregnancies, including 1274 SGA pregnancies, Ruiz-Martinez et al. developed a new risk stratification model based on maternal, fetal and placental conditions. The authors identified nine SGA clinical phenotypes that were associated with different patterns of risk for adverse perinatal outcome, highlighting the importance of considering clinical information in addition to Doppler parameters and estimated fetal weight for risk stratification and management of SGA.
Clinical severity of SARS-CoV-2 infection among vaccinated and unvaccinated pregnancies during the Omicron wave
It has been suggested that the Omicron variant of SARS-CoV-2 is associated with milder COVID-19 and reduced effectiveness of COVID-19 vaccines. The report by Birol Ilter et al. is the first to provide data on the outcome of Omicron variant infection in vaccinated vs unvaccinated pregnant women. The findings of the study demonstrate that unvaccinated women have a significantly higher risk of moderate or severe COVID-19 and are more likely to require oxygen support and intensive care unit admission. This emphasizes the importance of recommending COVID-19 vaccination to pregnant women despite the prevalence of the milder Omicron variant.
Coming up next month…
- A systematic review and meta-analysis evaluating the outcome of patients with aortic stenosis following fetal aortic valvuloplasty. Preview the Accepted Article.
- A study evaluating postnatal outcome of fetuses with critical aortic stenosis and investigating potential predictors of biventricular circulation following fetal aortic valvuloplasty. Preview the Accepted Article.
- A prospective study comparing ophthalmic artery Doppler with PlGF and sFlt-1/PlGF ratio at 35–37 weeks’ gestation in prediction of imminent pre-eclampsia. Preview the Accepted Article.