The prenatal diagnostic indicators of placenta accreta spectrum disorders

Placenta accreta spectrum (PAS) disorders refers to a heterogeneous group of anomalies distinguished by abnormal adhesion or invasion of chorionic villi through the myometrium and uterine serosa. PAS frequently results in life-threatening complications, including postpartum hemorrhage and hysterotomy. The incidence of PAS has increased recently as a result of rising cesarean section rates. Consequently, prenatal screening for PAS is essential. Despite the need to increase specificity, ultrasound is still considered a primary adjunct. Given the dangers and adverse effects of PAS, it is necessary to identify pertinent markers and validate indicators to improve prenatal diagnosis. This article summarizes the predictors regarding biomarkers, ultrasound indicators, and magnetic resonance imaging (MRI) features. In addition, we discuss the effectiveness of joint diagnosis and the most recent research on PAS. In particular, we focus on (a) posterior placental implantation and (b) accreta after in vitro fertilization-embryo transfer, both of which have low diagnostic rates. At last, we graphically display the prenatal diagnostic indicators and each diagnostic performance.

Circulating microparticle proteins predict pregnancies complicated by placenta accreta spectrum

Placenta accreta spectrum (PAS) is characterized by abnormal attachment of the placenta to the uterus, and attempts at placental delivery can lead to catastrophic maternal hemorrhage and death. Multidisciplinary delivery planning can significantly improve outcomes; however, current diagnostics are lacking as approximately half of pregnancies with PAS are undiagnosed prior to delivery. This is a nested case-control study of 35 cases and 70 controls with the primary objective of identifying circulating microparticle (CMP) protein panels that identify pregnancies complicated by PAS. Size exclusion chromatography and liquid chromatography with tandem mass spectrometry were used for CMP protein isolation and identification, respectively. A two-step iterative workflow was used to establish putative panels. Using plasma sampled at a median of 26 weeks' gestation, five CMP proteins distinguished PAS from controls with a mean area under the curve (AUC) of 0.83. For a separate sample taken at a median of 35 weeks' gestation, the mean AUC was 0.78. In the second trimester, canonical pathway analyses demonstrate over-representation of processes related to iron homeostasis and erythropoietin signaling. In the third trimester, these analyses revealed abnormal immune function. CMP proteins classify PAS well prior to delivery and have potential to significantly reduce maternal morbidity and mortality.

Potential Serum Biomarkers in Prenatal Diagnosis of Placenta Accreta Spectrum

Placenta accreta spectrum (PAS) refers to the abnormal invasion of trophoblastic tissues. Because of its increasing morbidity and possibility of catastrophic outcomes, PAS requires an antenatal diagnosis and making full preparations in advance to realize safe delivery. Current clinical screening modalities for PAS are not always conclusive. Recently, it has been reported that bio-markers detected in maternal serum have the potential for predicting PAS during pregnancy. Some of these biomarkers, such as β-hcg, AFP, PAPP-A, and cffDNA, can be clinically detected. It is convenient for us to test and compare with standard threshold. However, how can we distinguishing PAS from other pregnancy complications through these biomarkers remains complicated. Some biomarkers are specific, such as microRNA and placenta-specific mRNA. They are stability and reliability. These biomarkers are currently research hotspots. This study aims to summarize the characteristics of the newly reported biomarkers and to point out their potential application and current limitations to provide a basis for future research. Finally, the combination of imageological examination and biomarkers will be an attractive future theme to study in diagnosing this challenging condition.

The role of fetal fibronectin and plasminogen activator inhibitor 1 biomarkers in antenatal prediction of placenta accreta spectrum

In this study, we aimed to assess the determining role of foetal fibronectin (FFN) and plasminogen activator inhibitor type (PAI-1) levels in the antenatal prediction of placenta accreta spectrum in cases with risk factors for placenta accreta spectrum. Singleton live pregnancies with placenta previa or low-lying placenta within 32-34 weeks of gestation were included in the study. The cases were divided into two groups after delivery as those with PAS and those with normal placentation. 54 cases diagnosed with placenta previa or low-lying placenta were included in the study. 17 of the cases underwent peripartum hysterectomy due to placenta accreta spectrum. 37 cases with normal placentation underwent caesarean delivery. Foetal fibronectin (p:.03) and PAI-1 (p:.02) levels were determined to be significantly different between cases with placenta accreta spectrum and cases with normal placentation. AUC for foetal FFN was calculated to be 0.69, while the AUC for, PAI-1was 0.66. Results for both FFN and PAI-1 were not found useful enough for the diagnosis of PAS. IMPACT STATEMENTWhat is already known on this subject? We lack biomarkers which can identify placenta accreta spectrum.What do the results of this study add? Maternal plasma levels of FFN and PAI-1 significantly altered in PASWhat are the implications of these findings for clinical practice and/or future research? If multiple of median values of FFN and PAI-1 levels in maternal blood are determined in future studies, it can be used in the antenatal diagnosis of PAS cases.

The potential risk factors of placenta increta and the role of octamethylcyclotetrasiloxane

BACKGROUND

The study aimed to investigate the potential risk factors for the placenta accreta spectrum (PAS), determine the predictive value of a diagnostic model, and evaluate the effects of octamethylcyclotetrasiloxane (OMCTS) on trophoblast proliferation and migration.

METHODS

This case-control study included 244 pregnant women with PAS and 327 normal pregnant women who visited Guangzhou Women and Children's Medical Centre, China, from January 2014 to December 2017. Blood was collected from 42 women with PAS and 77 controls, and plasma specimens were analyzed by gas chromatography-time-of-flight mass spectrometry. In addition, the proliferation and migration of trophoblast cells were examined after treatment with OMCTS.

RESULTS

We found an association between the risk of PAS and clinical factors related to fasting blood glucose levels (BS0, OR = 5.78), as well as factors related to endometrial injury [history of cesarean section (OR = 179.59), uterine scarring (OR = 68.37), and history of abortion (OR = 5.66)]. Equally important, pregnant women with PAS had significantly higher plasma OMCTS concentrations than controls. In vitro, we found that OMCTS could promote the proliferation and migration of HTR8/SVneo cells. The model of combining clinical factors and OMCTS had a good performance in PAS prediction (AUC = 0.97, 95% CI 0.78-0.93).

CONCLUSIONS

The early diagnosis of PAS in pregnant women requires assessing risk factors, metabolic status, and BS0 levels before 20 weeks of gestation. OMCTS may be related to the development of PAS by promoting trophoblast cell proliferation and migration.

Delta Neutrophil Index as a Promising Biomarker for Placental Implantation Disorders

OBJECTIVE

We aimed to investigate the value of maternal serum delta neutrophil index (DNI) levels in predicting placenta accreta spectrum in patients with placenta previa.

METHODS

The patients who were found to have placenta previa totalis were included in our study. Location of placental implantation and depth of myometrial invasion were defined by transabdominal and transvaginal 2D gray scale and Doppler sonography and confirmed during cesarean section and histopathological evaluation. Patients were subjected to complete blood counts, including prenatal hemoglobin level, total white blood cell count, differential leukocyte count, and platelet count. The following formula was used to calculate the DNI level: DNI (%)=(leukocyte subfraction analyzed by cytochemical reaction in the MPO channel) - (leukocyte subfraction analyzed using the nuclear lobularity channel with reflected light beam measurements).

RESULTS

Placenta previa was detected in 295 patients; 31 of them had PAS. As the control group, 189 patients were evaluated. In the group with PAS, the DNI value was significantly higher (p<0.05) than the other groups. DNI value in the group with previa only was also significantly higher (p<0.05) than the control group. In the univariate model, a significant (p<0.05) effect of DNI value and number of cesarean sections was observed in separating patients with previa only and PAS. In the multivariate model, a significant independent (p>0.05) effect of the DNI value was observed in separating patients with previa only and PAS. Significant efficiency of DNI value [area under the curve 0.899 (0.814-0.984)] was observed in differentiating patients with previa only and PAS. Significant efficacy of DNI 5 cut-off value [area under the curve 0.858 (0.770-0.946)] was observed in distinguishing patients with previa only and PAS (sensitivity 80.0%, positive predictive value 64.9%, specificity 91.6%, negative predictive value 95.9%) CONCLUSION: Maternal DNI values seem to be beneficial with respect to both previa and invasion prediction. Although more comprehensive studies are needed to test this proposition, prediction studies of this practical test should be done in different trimesters and its usability with respect to preventing maternal-fetal morbidity should be investigated.

What we know about placenta accreta spectrum (PAS)

Placenta accreta spectrum (PAS) is an umbrella term for a variety of pregnancy complications due to abnormal placental implantation, including placenta accreta, placenta increta and placenta percreta. During the past several decades, the prevalence of PAS has been increasing, and the clinical importance of this disease is significant because of the severe complications. In this review, we summarized the available evidence-based data for PAS in various aspects: prevalence, risk factors, pathogenesis, clinical presentation and prenatal screening, and clinical management. Meanwhile, we provided a series of prospects in each section for further studies on PAS. Moreover, we first present a visualized workflow for the management of PAS from three steps: predelivery, during delivery and postdelivery.

First trimester serum PAPP-A is associated with placenta accreta: a retrospective study

PURPOSE

Our objective of this study was to investigate whether first trimester serum pregnancy-associated plasma protein-A (PAPP-A) differed amongst pregnancies with placenta previa-accreta and non-adherent placenta previa and healthy pregnancies by a retrospective cohort analysis.

METHODS

A total of 177 pregnant females were included in the study, as follows: 35 cases of placenta previa-accreta, 30 cases of non-adherent placenta previa, and 112 cases of BMI and age matched, healthy pregnant controls. PAPP-A multiples of the median (MoM) were acquired from laboratory data files in 1 January 2017-30 September 2019. The probable maternal serum biochemical predictor of placenta accreta was analyzed by using multiple logistic regression analysis.

RESULTS

PAPP-A MoM of placenta previa-accreta group was significantly higher than those of the non-adherent placenta previa group and control group (p = 0.009 < 0.05, p < 0.001). Serum PAPP-A was found to be significantly positively associated with placenta accreta after adjusted gestational week at time of blood sampling, BMI, age, smoking, and previous cesarean section history (OR: 3.51; 95% CI: 1.77-6.94; p = 0.0003 < 0.05). In addition, smoking (OR: 9.17; 95% CI: 1.69-49.62; p = 0.010 < 0.05) and previous cesarean section history (OR: 2.75; 95% CI: 1.23-6.17; p = 0.014 < 0.05) were also significantly associated with placenta accreta.

CONCLUSION

Increased first trimester serum PAPP-A was significantly positively associated with placenta accreta, suggesting that the potential role of PAPP-A in identifying pregnancies at high risk for placenta accreta. Smoking and previous cesarean section history may be the risk factors for accreta in placenta previa patients.

Biomarkers of abnormally invasive placenta

INTRODUCTION

Abnormally invasive placenta (AIP, aka placenta accreta spectrum; PAS) is an increasingly common pregnancy pathology, which, despite significant morbidity risk to the mother, is often undiagnosed prior to delivery. We tested several potential biomarkers in plasma from PAS mothers to determine whether any were sufficiently robust for a formal, diagnostic accuracy study.

METHODS

We examined hyperglycosylated hCG (h-hCG), decorin and IL-8, based on biological plausibility and literature indications that they might be altered in PAS. These analytes were assayed by ELISA in maternal plasma from five groups, comprising (1) normal term controls, (2) placenta previa controls, and cases of (3) placenta increta/percreta without placenta previa, (4) placenta previa increta/percreta and (5) placenta previa accreta.

RESULTS

There were no differences in h-hCG, ß-hCG or the h-hCG/ß-hCG ratio between the groups. Mean decorin levels were increased in previa controls (Group 2) compared to the other groups, but there was substantial overlap between the individual values. While an initial multiplex assay showed a greater value for IL-8 in the placenta previa increta/percreta group (Group 4) compared to placenta previa controls (Group 2), the subsequent validation ELISA for IL-8 showed no differences between the groups.

DISCUSSION

We conclude that the absence of differences and the extent of overlap between cases and controls does not justify further assessment of these biomarkers.

Significance of the routine first-trimester antenatal screening program for aneuploidy in the assessment of the risk of placenta accreta spectrum disorders

Objective To select a group at high risk of placenta accreta spectrum disorders (PAS) based on the data of serum screening in the first trimester. Methods A retrospective analysis of 48 patients with abnormal placental location (AP), including placenta previa (PP) only (n = 23) and PP and PAS (n = 25), was performed. Additionally, the AP group was divided depending on the blood loss volume: not higher than 1000 mL (LBL) (n = 29) and higher than 1000 mL (HBL) (n = 19); diagnostic term of PAS by ultrasound, data pregnancy-associated plasma protein-A (РAРР-A) and free β subunit of human chorionic gonadotropin (free β-hCG) multiple of median (MоM) at 11+0-13+6 weeks of gestation were evaluated. Serological markers were compared with the data of 39 healthy pregnant women with scar after previous cesarean section and normal placental location (control). Results The mean gestation at diagnostic term of PAS was 29 weeks. PAPP-Р MоM [mean (M) ± standard deviation (SD)] was: in controls, 1.07 ± 0.47; in the AP group, 1.59 ± 0.24; in PP, 1.91 ± 1.52; in PAS, 1.30 ± 0.85; in LBL, 1.37 ± 1.20; in HBL, 1.91 ± 1.24. The difference between control/AP, control/PP, control/PAS, PP/PAS, control/LBL, control/HBL and LBL/HBL was Р = 0.256, 0.145, 0.640, 0.311, 0.954, 0.025 and 0.09, respectively. Free β-hCG MoM (M ± SD) was: in controls, 1.08 ± 0.69, in AP, 1.31 ± 0.96; in PP, 1.46 ± 0.19; in PAS, 1.16 ± 0.65; in LBL, 1.30 ± 0.06; in HBL, 1.32 ± 0.78. Comparison of free β-hCG AP with controls and between subgroups did not reveal a significant difference. Conclusion Underestimation of PAS risk factors in pregnant women with AP leads to late diagnostics of pathology only in the third trimester. The assessment of the РAРР-A level in the first trimester may be helpful for the early prognosis of pathological blood loss at delivery for pregnant women with AP and for forming the high-risk group for PAS.

Second Trimester Biochemical Markers as Possible Predictors of Pathological Placentation: A Retrospective Case-Control Study

OBJECTIVE

We aimed to evaluate the association between second trimester biochemical markers and pathological placentation.

METHODS

This was a retrospective case-control study (2007-2014) of singleton gestations at a university-affiliated tertiary center. Women with pathologic placentation were subdivided into three groups: placenta accreta (group A), placenta previa (group B), or both (group C). We compared second trimester biochemical screening markers taken between 16 + 0 and 19 + 6 weeks of gestation between groups A, B, and C, and women with normal placentation (group D). Obstetrical and neonatal outcomes, risk factors for pathologic placentation, and second trimester biochemical marker values were compared between groups.

RESULTS

Overall, 301 deliveries were evaluated: 64 (21%) in group A, 66 (22%) in group B, 17 (6%) in group C, and 153 (51%) in group D. Each of the pathological placentation groups individually had a higher median alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) multiples of median (MoM) than the controls, with the highest values of AFP and hCG observed among women with placenta accreta and the lowest values among the controls. When a multivariant analysis was applied, the hCG levels remained significantly correlated with pathological placentation. Receiver operation characteristic curves for AFP, hCG, or both were computed. For AFP the area under the ROC curve (AUC) was 0.573 (95% CI 0.515-0.630, p < 0.0274) and a cut-off value above 0.99 MoM demonstrated a sensitivity and specificity of 71 and 46%, respectively, for the prediction of pathological placentation. For hCG, the AUC was 0.662 (95% CI 0.605-0.715, p < 0.0001) and a cut-off value of 1.25 MoM demonstrated a sensitivity and specificity of 53 and 68%. When both markers were plotted, the AUC was 0.668 (95% CI 0.611-0.721, p < 0.0001) and sensitivity and specificity were 63 and 64%, respectively. A percentile MoM cut-off approach distinguished between two groups: a high-risk group (patients with AFP or hCG or both above the 75th percentile, odds ratio (OR) for pathological placentation 2.27, 95% CI 1.42-3.63), and a low-risk group (patients with AFP or hCG or both below the 25th percentile, OR for pathological placentation 0.38, 95% CI 0.24-0.60).

CONCLUSION

Second trimester biomarkers such as hCG and AFP can be used to raise a suspicion towards characterizing women into high-risk and low-risk groups for pathological placentation.

Abnormal placentation

The term "morbidly adherent placenta" has recently been introduced to describe the spectrum of disorders including placenta accreta, increta and percreta. Due to excessive invasion of the placenta into the uterus there is associated significant maternal morbidity and mortality. Most significant risk factors for morbidly adherent placenta include history of prior cesarean delivery as well as placenta previa in the current pregnancy. Ultrasound remains the gold standard for antenatal diagnosis, however, in recent years MRI has assisted in identifying complex parametrial involvement. Optimizing maternal and neonatal outcomes involves early prenatal diagnosis, a multi-disciplinary team-based approach, and referral to an experienced center.

Placenta Accreta Spectrum: A Review of Pathology, Molecular Biology, and Biomarkers

Background. Placenta accreta spectrum (PAS) is a condition of abnormal placental invasion encompassing placenta accreta, increta, and percreta and is a major cause of severe maternal morbidity and mortality. The diagnosis of a PAS is made on the basis of histopathologic examination and characterised by an absence of decidua and chorionic villi are seen to directly adjacent to myometrial fibres. The underlying molecular biology of PAS is a complex process that requires further research; for ease, we have divided these processes into angiogenesis, proliferation, and inflammation/invasion. A number of diagnostic serum biomarkers have been investigated in PAS, including human chorionic gonadotropin (HCG), pregnancy-associated plasma protein-A (PAPP-A), and alpha-fetoprotein (AFP). They have shown variable reliability and variability of measurement depending on gestational age at sampling. At present, a sensitive serum biomarker for invasive placentation remains elusive. In summary, there are a limited number of studies that have contributed to our understanding of the molecular biology of PAS, and additional biomarkers are needed to aid diagnosis and disease stratification.

Down-regulation of soluble fms-like tyrosine kinase 1 expression in invasive placentation

PURPOSE

To confirm reduced expression of soluble fms-like tyrosine kinase 1 (sFlt-1) in accreta/increta.

METHODS

Formalin-fixed tissue sections from 11 peripartum hysterectomies with invasive placentation and 5 controls were stained for sFlt-1. Stain intensity was scored in selected 100× microscopic fields. We compared sFlt-1 expression in invasive areas among cases, non-invasive areas among cases and areas from control placentas.

RESULTS

Chorionic villi displayed significantly decreased sFlt-1 expression in invasive areas of cases compared to control placentas (p = 0.003), as well as in non-invasive areas of cases compared to control placentas (p = 0.01). There was no difference in sFlt-1 expression between invasive and non-invasive areas among cases.

CONCLUSIONS

Expression of sFlt-1 is diminished in villous trophoblasts from patients with placenta increta or percreta. Local depth of invasion was not associated with sFlt-1 expression, suggesting a more global abnormality across the implantation site rather than localized to areas of histologic invasion.

Texture analysis of the developing human brain using customization of a knowledge-based system

Background: Pattern recognition software originally designed for geospatial and other technical applications could be trained by physicians and used as texture-analysis tools for evidence-based practice, in order to improve diagnostic imaging examination during pregnancy.Methods: Various machine-learning techniques and customized datasets were assessed for training of an integrable knowledge-based system (KBS), to determine a hypothetical methodology for texture classification of closely-related anatomical structures in fetal brain magnetic resonance (MR) images. Samples were manually categorized according to the magnetic field of the MRI scanner (i.e. 1.5-tesla (1.5T), 3-tesla (3T)), rotational planes (i.e. coronal, sagittal and axial), and signal weighting (i.e. spin-lattice, spin-spin, relaxation, proton density). In the machine-learning sessions, the operator manually selected relevant regions of interest (ROI) in 1.5/3T MR images. Semi-automatic procedures in MaZda/B11 were performed to determine optimal parameter sets for ROI classification. Four classes were defined: ventricles, thalamus, grey matter, and white matter. Various textures analysis methods were tested. The KBS performed automatic data pre-processing and semi-automatic classification of ROIs.Results: After testing 3456 ROIs, statistical binary classification revealed that combination of reduction techniques with linear discriminant algorithms (LDA) or nonlinear discriminant algorithms (NDA) yielded the best scoring in terms of sensitivity (both 100%, 95% CI: 99.79-100), specificity (both 100%, 95% CI: 99.79-100) and Fisher coefficient (≈E+4, ≈E+5, respectively). Conclusions: LDA and NDA in MaZda can be useful data mining tools for screening a population of interest subjected to a clinical test.