Ultrasound evaluation of the placenta in healthy and placental syndrome pregnancies: A systematic review

Presence and Size of Placental Lakes on 20-Week Fetal Anatomy Ultrasound and Obstetrical Outcomes

Our objective was to determine if placental lake presence or size is associated with adverse pregnancy outcomes. This was a retrospective cohort of patients who had fetal anatomy ultrasounds at 18-22 weeks and delivered between 2018 and 2022. Placental lakes were classified as small (>2.0 to 3.9 cm) or large (≥4 cm). Multiple gestations, placenta previas, and placenta accretas were excluded. Outcomes included low birthweight, cesarean delivery, primary cesarean for non-reassuring fetal heart tracing, fetal growth restriction, preterm birth, and severe preeclampsia. A total of 1052 patients were included; 294 had placental lakes (204 small, 90 large). No differences in pregnancy outcomes were observed.

Long-Term Neurologic Consequences following Fetal Growth Restriction: The Impact on Brain Reserve

BACKGROUND

Fetal growth restriction (FGR) corresponds to the fetus's inability to achieve an adequate weight gain based on genetic potential and gestational age. It is an important cause of morbidity and mortality.

SUMMARY

In this review, we address the challenges of diagnosis and classification of FGR. We review how chronic fetal hypoxia impacts brain development. We describe recent advances on placental and fetal brain imaging using magnetic resonance imaging and how they offer new noninvasive means to study growth restriction in humans. We go on to review the impact of FGR on brain integrity in the neonatal period, later childhood, and adulthood and review available therapies.

KEY MESSAGES

FGR consequences are not limited to the perinatal period. We hypothesize that impaired brain reserve, as defined by structure and size, may predict some concerning epidemiological data of impaired cognitive outcomes and dementia with aging in this group of patients.

CircTHBS1 promotes trophoblast cell migration and invasion and inhibits trophoblast apoptosis by regulating miR-136-3p/IGF2R axis

The precise molecular mechanism behind fetal growth restriction (FGR) is still unclear, although there is a strong connection between placental dysfunction, inadequate trophoblast invasion, and its etiology and pathogenesis. As a new type of non-coding RNA, circRNA has been shown to play a crucial role in the development of FGR. This investigation identified the downregulation of hsa_circ_0034533 (circTHBS1) in FGR placentas through high-sequencing analysis and confirmed this finding in 25 clinical placenta samples using qRT-PCR. Subsequent in vitro functional assays demonstrated that silencing circTHBS1 inhibited trophoblast proliferation, migration, invasion, and epithelial mesenchymal transition (EMT) progression and promoted apoptosis. Furthermore, when circTHBS1 was overexpressed, cell function experiments showed the opposite result. Analysis using fluorescence in situ hybridization revealed that circTHBS1 was primarily found in the cytoplasmic region. Through bioinformatics analysis, we anticipated the involvement of miR-136-3p and IGF2R in downstream processes, which was subsequently validated through qRT-PCR and dual-luciferase assays. Moreover, the inhibition of miR-136-3p or the overexpression of IGF2R partially reinstated proliferation, migration, and invasion abilities following the silencing of circTHBS1. In summary, the circTHBS1/miR-136-3p/IGF2R axis plays a crucial role in the progression and development of FGR, offering potential avenues for the exploration of biological indicators and treatment targets.

Two-dimensional (2D) placental ultrasound measurements - The correlation with placental volume measured by magnetic resonance imaging (MRI)

INTRODUCTION

Information about placental size in ongoing pregnancies may aid the identification of pregnancies with increased risk of adverse outcome. Placental volume can be measured using magnetic resonance imaging (MRI). However, this method is not universally available in antenatal care. Ultrasound is the diagnostic tool of choice in pregnancy. Therefore, we studied whether simple two-dimensional (2D) ultrasound placental measurements were correlated with placental volume measured by MRI.

METHODS

We examined a convenience sample of 104 ongoing pregnancies at gestational week 27, using both ultrasound and MRI. The ultrasound measurements included placental length, width and thickness. Placental volume was measured using MRI. The correlation between each 2D placental ultrasound measurement and placental volume was estimated by applying Pearson's correlation coefficient (r).

RESULTS

Mean placental length was 17.2 cm (SD 2.1 cm), mean width was 14.7 cm (SD 2.1 cm), and mean thickness was 3.2 cm (SD 0.6 cm). Mean placental volume was 536 cm3 (SD 137 cm3). The 2D ultrasound measurements showed poor correlation with placental volume (placental length; r = 0.27, width; r = 0.37, and thickness r = 0.13).

DISCUSSION

Simple 2D ultrasound measurements of the placenta were poorly correlated with placental volume and cannot be used as proximate measures of placental volume. Our finding may be explained by the large variation between pregnancies in intrauterine placental shape.

Prenatal diagnosis of bilobate placenta: incidence, risk factors and impact on pregnancy outcomes

OBJECTIVES

To investigate the incidence and risk factors of bilobate placenta, as well as to assess its impact on preeclampsia (PE), preterm delivery (PTD) and small-for-gestational age (SGA) neonates.

METHODS

A prospective study of singleton pregnancies, undergoing routine anomaly scan at 20+0-23+6 gestational weeks, was conducted, between 2018 and 2022. The impact of prenatally diagnosed bilobate placenta on PE, PTD and SGA was assessed. Multivariate logistic regression models were employed to assess the independent association between bilobate placenta and the main pregnancy outcomes, using specific confounders. Additionally, a risk factor analysis was performed.

RESULTS

The study population included 6,454 pregnancies; the incidence of prenatally diagnosed bilobate placenta was 2.0 % (n=129). Bilobate placenta was associated with PE (aOR: 1.721; 95 % CI: 1.014-2.922), while no statistically significant association was found between this anatomical variation and SGA (aOR: 1.059; 95 % CI: 0.665-1.686) or PTD (aOR: 1.317; 95 % CI: 0.773-2.246). Furthermore, pregnancies with prenatally diagnosed bilobate placenta had an increased prevalence of abnormal cord insertion (marginal or velamentous) (9.8 vs. 27.1 %; p<0.001) and increased mean UtA PI z-score (0.03 vs. 0.23; p=0.039). Conception via ART (aOR: 3.669; 95 % CI: 2.248-5.989), previous history of 1st trimester miscarriage (aOR: 1.814; 95 % CI: 1.218-2.700) and advancing maternal age (aOR: 1.069; 95 % CI: 1.031-1.110) were identified as major risk factors for bilobate placenta.

CONCLUSIONS

Bilobate placenta, excluding cases of co-existing vasa previa, is associated with higher incidence of PE, increased mean UtA PI z-score and higher probability of abnormal cord insertion, but not with increased risk for SGA or PTD. It is more common in pregnancies following ART and in women with a previous 1st trimester miscarriage.

Evaluation of placental oxygenation by near-infrared spectroscopy in relation to ultrasound maturation grade in physiological term pregnancies

A prospective observational study (ClinicalTrial ID: NCT05771415) was conducted to compare placental oxygenation in low-risk, uncomplicated term pregnancies measured by near-infrared spectroscopy (NIRS) in relation to the placental maturity grade determined by ultrasound assessment according to the Grannum scale. We included 34 pregnancies divided into two groups according to placental maturation. For each pregnancy, measurements were taken at the site above the central part of the placenta (test) and at the site outside of the placenta on the lower abdomen (control). Student's t-test was used to compare tissue oxygenation index (TOI) values among the study groups. The normality of distribution was proven by the Kolmogorov‒Smirnov test. In women with low placental maturity grade, the mean TOI value above the placenta was 70.38 ± 3.72, which was lower than the respective value in women with high placental maturity grade (77.99 ± 3.71; p < 0.001). The TOI values above the placenta and the control site were significantly different in both groups (70.38 ± 3.72 vs 67.83 ± 3.21 and 77.99 ± 3.71 vs 69.41 ± 3.93; p < 0.001). The results offer a new perspective on placental function based on specific non-invasive real-time oxygenation measurements. Unfortunately, and because of technical limitations, NIRS cannot yet be implemented as a routine clinical tool.

Application of Color Doppler with 3- and 4-Dimensional Ultrasonography in the Prenatal Evaluation of Fetal Extracardiac and Placental Abnormalities

Using color Doppler flow imaging or high-definition flow imaging with three-dimensional volume or spatio-temporal image correlation (STIC) in the glass-body mode allows displaying both gray-scale and color information of the heart cycle-related flow events and vessel spatial relationship. Conventionally, STIC in the glass-body mode has been used to examine the fetal heart and assess heart defects. Recently, a novel application of STIC in the visualization of abdominal precordial veins and intraplacental vascularization in singleton pregnancies has been reported. The aim of this present review is to discuss the use of color Doppler with three- and four-dimensional ultrasonography in the evaluation of extracardiac, placental, umbilical cord and twin abnormalities with examples. The glass-body mode is complementary to conventional 2D ultrasonography. Further studies are required to investigate use of the glass-body mode in the assessment of intraplacental vascularization in singleton and twin pregnancies.

Fetal growth restriction and stillbirth: Biomarkers for identifying at risk fetuses

Fetal growth restriction (FGR) is a major cause of stillbirth, prematurity and impaired neurodevelopment. Its etiology is multifactorial, but many cases are related to impaired placental development and dysfunction, with reduced nutrient and oxygen supply. The fetus has a remarkable ability to respond to hypoxic challenges and mounts protective adaptations to match growth to reduced nutrient availability. However, with progressive placental dysfunction, chronic hypoxia may progress to a level where fetus can no longer adapt, or there may be superimposed acute hypoxic events. Improving detection and effective monitoring of progression is critical for the management of complicated pregnancies to balance the risk of worsening fetal oxygen deprivation in utero, against the consequences of iatrogenic preterm birth. Current surveillance modalities include frequent fetal Doppler ultrasound, and fetal heart rate monitoring. However, nearly half of FGR cases are not detected in utero, and conventional surveillance does not prevent a high proportion of stillbirths. We review diagnostic challenges and limitations in current screening and monitoring practices and discuss potential ways to better identify FGR, and, critically, to identify the “tipping point” when a chronically hypoxic fetus is at risk of progressive acidosis and stillbirth.

Ultrasound Multiparametric Assessment of the Impact of Hypertensive Disorders of Pregnancy on Fetal Cardiac Function and Growth and Development

Objective

To evaluate the ultrasound multiparametric assessment of the impact of hypertensive disorders of pregnancy (HDP) on fetal cardiac function and growth and development.

Methods

In this prospective study, 98 cases of HDP treated in our institution were recruited into a study group, and 100 pregnant women with healthy singleton pregnancies were included in a control group. All eligible patients were also assigned to either study group A (HDP fetuses with growth restriction) or study group B (HDP fetuses with normal growth). Fetal echocardiography was performed on all eligible participants to obtain hemodynamic and cardiac function parameters for the evaluation of fetal growth and development, and the impact of HDP on fetal heart function and growth and development was analyzed.

Results

HDP fetuses were associated with smaller head circumference, biparietal diameter, femoral length, and abdominal circumference versus healthy fetuses. The study group had a higher resistance index (RI) and pulsatility index (PI) of umbilical artery (UA), ductus venous (DV), pulmonary vein (PV), and lower RI and PI of aortic isthmus (AoI) than the control group. The study group showed higher left and right ventricular isovolumic contraction time (IVCT), isovolumic relaxation time (IVRT), and myocardial performance index (MPI) values and lower mitral and tricuspid E wave and E/A values than the control group. The systolic blood pressure was positively correlated with PI, RI of UA, DV, and PV, and left and right ventricular IVCT, IVRT, and MPI and negatively correlated with PI and RI of AoI and mitral and tricuspid E wave and E/A values of HDP fetuses. The peak systolic/diastolic flow rate (S/D), PI, and RI of umbilical blood flow in study group A were higher than those in study group B. Umbilical blood flow S/D showed the highest AUC and specificity for predicting fetal growth restriction, and PI had the highest sensitivity for predicting fetal growth restriction.

Conclusion

HDP compromises fetal cardiac function and growth, and ultrasound multiparametric assessment provides accurate detection of fetal cardiac function and hemodynamics changes. The patient's condition can be monitored through the assessment of ultrasound parameters of fetal growth and development.

The association between decidual vasculopathy and abnormal uterine artery Doppler measurement

INTRODUCTION

Placental syndrome is an umbrella term encompassing the clinical phenotypes of preeclampsia and fetal growth restriction, and is associated with high maternal and neonatal morbidity. In women with placental syndrome, histologicl examination of the uteroplacental unit commonly demonstrates pathological lesions, such as decidual vasculopathy. Decidual vasculopathy are pathological changes in the spiral arteries, which are associated with adverse outcome in preeclampsia and long-term maternal cardiovascular health. The relation between placental syndrome phenotypes and placental pathology has been previously demonstrated; however, the role of uteroplacental Doppler measurements as a link between placental syndrome phenotypes and the underlying placental pathology is still unclear. We hypothesized that decidual vasculopathy is associated with abnormal uteroplacental Doppler profiles and ultrasound placental parameters, independent of clinical phenotype.

MATERIAL AND METHODS

We performed a retrospective analysis of data from a prospective cohort of pregnancies with placental syndrome, as well as cases without hypertensive disease or fetal growth restriction. The study group was divided into women with decidual vasculopathy on histologic analysis of placental specimen and those without the lesions. Outcome parameters included maternal and fetal Dopplers, estimated fetal weight, placental weight and thickness, placental lacunae and abnormal placental calcification.

RESULTS

Compared with the women without the lesions (n = 91), the group with decidual vasculopathy (n = 25) had a higher mean uterine artery pulsatility index (1.70 vs 0.81, p < 0.001) and uterine artery pulsatility index percentile (>p99 vs p67, p < 0.001). Decidual vasculopathy was associated with abnormal uterine artery Doppler profile (defined as pulsatility index p > 95 and/or bilateral notch) (82%) compared with women without the lesions (33%) (odds ratio [OR] 9.3, 95% CI 2.4-36.0), which remained significant after adjusting for possible confounding factors preeclampsia, tobacco use and gestational age at birth (OR 7.1, 95% CI 1.3-39.1). Decidual vasculopathy was not associated with fetal Doppler abnormalities or placental parameters and only modestly so with lower cerebroplacental ratio (p = 0.036).

CONCLUSIONS

Histologic decidual vasculopathy is associated with abnormal uterine artery Doppler, independent of clinical phenotype during pregnancy.

The Role of Inorganics in Preeclampsia Assessed by Multiscale Multimodal Characterization of Placentae

Preeclampsia is one of the most dangerous diseases in pregnancy. Because of the hypertensive nature of preeclampsia, placental calcifications are believed to be a predictor for its occurrence, analogous to their role in cardiovascular diseases. However, the prevalence and the relevance of calcifications for the clinical outcome with respect to preeclampsia remains controversial. In addition, the role of other inorganic components present in the placental tissue in the development of preeclampsia has rarely been investigated. In this work, we therefore characterized inorganic constituents in placental tissue in groups of both normotensive and preeclamptic patients (N = 20 each) using a multi-scale and multi-modal approach. Examinations included elemental analysis (metallomics), sonography, computed tomography (CT), histology, scanning electron microscopy, X-ray fluorescence and energy dispersive X-ray spectroscopy. Our data show that tissue contents of several heavy metals (Al, Cd, Ni, Co, Mn, Pb, and As) were elevated whereas the Rb content was decreased in preeclamptic compared to normotensive placentae. However, the median mineral content (Ca, P, Mg, Na, K) was remarkably comparable between the two groups and CT showed lower calcified volumes and fewer crystalline deposits in preeclamptic placentae. Electron microscopy investigations revealed four distinct types of calcifications, all predominantly composed of calcium, phosphorus and oxygen with variable contents of magnesium in tissues of both maternal and fetal origin in both preeclamptic and normotensive placentae. In conclusion our study suggests that heavy metals, combined with other factors, can be associated with the development of preeclampsia, however, with no obvious correlation between calcifications and preeclampsia.

Emerging placental biomarkers of health and disease through advanced magnetic resonance imaging (MRI)

Placental dysfunction is a major cause of fetal demise, fetal growth restriction, and preterm birth, as well as significant maternal morbidity and mortality. Infant survivors of placental dysfunction are at elevatedrisk for lifelong neuropsychiatric morbidity. However, despite the significant consequences of placental disease, there are no clinical tools to directly and non-invasively assess and measure placental function in pregnancy. In this work, we will review advanced MRI techniques applied to the study of the in vivo human placenta in order to better detail placental structure, architecture, and function. We will discuss the potential of these measures to serve as optimal biomarkers of placental dysfunction and review the evidence of these tools in the discrimination of health and disease in pregnancy. Efforts to advance our understanding of in vivo placental development are necessary if we are to optimize healthy pregnancy outcomes and prevent brain injury in successive generations. Current management of many high-risk pregnancies cannot address placental maldevelopment or injury, given the standard tools available to clinicians. Once accurate biomarkers of placental development and function are constructed, the subsequent steps will be to introduce maternal and fetal therapeutics targeting at optimizing placental function. Applying these biomarkers in future studies will allow for real-time assessments of safety and efficacy of novel interventions aimed at improving maternal-fetal well-being.

Current Resources for Evidence-Based Practice, September 2021

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes an assessment of safety of birth centers in the United States and commentaries on reviews focused on aspirin prophylaxis in pregnancy and the new gestational weight gain evidence summary from the United States Preventive Services Task Force.