Placenta accreta spectrum: pathophysiology and evidence-based anatomy for prenatal ultrasound imaging

Risk factors for placenta accreta spectrum without prior cesarean section: A case-control study in China

OBJECTIVE

To identify the risk factors for placenta accreta spectrum (PAS) disorders in women without prior cesarean section (CS).

METHODS

This retrospective case-control study investigated patients without prior CS who gave birth at Peking University Third Hospital between January 1, 2015 and December 31, 2021. Patients diagnosed with PAS according to the clinical diagnostic criteria of the 2019 International Federation of Gynecology and Obstetrics (FIGO) classification were included as the study group. Patients were matched as the control group according to delivery date and placenta previa, in a 1:2 allocation ratio. Maternal characteristics were compared between the two groups.

RESULTS

The study included 348 patients in the study group and 696 in the control group. The multivariate analysis showed that the independent risk factors of PAS consisted of operative hysteroscopy (once: adjusted odds ratio [aOR] 2.38, 95% CI 1.28-4.24, P = 0.006; twice or more: aOR 5.43, 95% CI 1.04-28.32, P = 0.045), uterine curettage (once: aOR 2.54, 95% CI 1.80-3.58, P < 0.001; twice: aOR 3.01, 95% CI 1.81-5.02, P < 0.001; three or more times: aOR 9.18, 95% CI 4.64-18.18, P < 0.001), multifetal pregnancy (aOR 5.64, 95% CI 3.01-10.57, P < 0.001), adenomyosis (aOR 2.77, 95% CI 1.23-6.22, P = 0.014), in vitro fertilization (aOR 1.51, 95% CI 1.04-2.20, P = 0.030) and pre-eclampsia (aOR 2.72, 95% CI 1.36-5.45, P = 0.005), and the independent protective factor was being multiparous (aOR 0.37, 95% CI 0.25-0.54, P < 0.001).

CONCLUSION

After controlling the effect of placenta previa, we found that patients with PAS without prior CS had unique maternal characteristics. Classification and quantification of the intrauterine surgeries they have undergone is essential for identifying high-risk patients. Early identification of high-risk groups by risk factors has the potential to improve the prognosis considerably.

Prophylactic Radiologic Interventions for Postpartum Hemorrhage Control in Women With Placenta Accreta Spectrum Disorder: A Systematic Review and Meta-analysis

OBJECTIVE

To quantify the association between prophylactic radiologic interventions and perioperative blood loss during cesarean delivery in women with placenta accreta spectrum disorder through a systematic review and network meta-analysis.

DATA SOURCES

On January 3, 2023, a literature search was conducted in PubMed, EMBASE, Cochrane Library, and Web of Science. We also checked ClinicalTrials.gov retrospectively. Prophylactic radiologic interventions to reduce bleeding during cesarean delivery involved preoperative placement of balloon catheters, distal (internal or common iliac arteries) or proximal (abdominal aorta), or sheaths (uterine arteries). The primary outcome was volume of blood loss; secondary outcomes were the number of red blood cell units transfused and adverse events. Studies including women who received an emergency cesarean delivery were excluded.

METHODS OF STUDY SELECTION

Two authors independently screened citations for relevance, extracted data, and assessed the risk of bias of individual studies with the Cochrane Risk of Bias in Non-randomized Studies of Interventions tool.

TABULTATION, INTEGRATION, AND RESULTS

From a total of 1,332 screened studies, 50 were included in the final analysis, comprising 5,962 women. These studies consisted of two randomized controlled trials and 48 observational studies. Thirty studies compared distal balloon occlusion with a control group, with a mean difference in blood loss of -406 mL (95% CI, -645 to -167). Fourteen studies compared proximal balloon occlusion with a control group, with a mean difference of -1,041 mL (95% CI, -1,371 to -710). Sensitivity analysis excluding studies with serious or critical risk of bias provided similar results. Five studies compared uterine artery embolization with a control group, all with serious or critical risk of bias; the mean difference was -936 mL (95% CI, -1,522 to -350). Reported information on adverse events was limited.

CONCLUSION

Although the predominance of observational studies in the included literature warrants caution in interpreting the findings of this meta-analysis, our findings suggest that prophylactic placement of balloon catheters or sheaths before planned cesarean delivery in women with placenta accreta spectrum disorder may, in some cases, substantially reduce perioperative blood loss. Further study is required to quantify the efficacy according to various severities of placenta accreta spectrum disorder and the associated safety of these radiologic interventions.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42022320922.

Diagnosis of placenta accreta spectrum using ultrasound texture feature fusion and machine learning

INTRODUCTION

Placenta accreta spectrum (PAS) is an obstetric disorder arising from the abnormal adherence of the placenta to the uterine wall, often leading to life-threatening complications including postpartum hemorrhage. Despite its significance, PAS remains frequently underdiagnosed before delivery. This study delves into the realm of machine learning to enhance the precision of PAS classification. We introduce two distinct models for PAS classification employing ultrasound texture features.

METHODS

The first model leverages machine learning techniques, harnessing texture features extracted from ultrasound scans. The second model adopts a linear classifier, utilizing integrated features derived from 'weighted z-scores'. A novel aspect of our approach is the amalgamation of classical machine learning and statistical-based methods for feature selection. This, coupled with a more transparent classification model based on quantitative image features, results in superior performance compared to conventional machine learning approaches.

RESULTS

Our linear classifier and machine learning models attain test accuracies of 87 % and 92 %, and 5-fold cross validation accuracies of 88.7 (4.4) and 83.0 (5.0), respectively.

CONCLUSIONS

The proposed models illustrate the effectiveness of practical and robust tools for enhanced PAS detection, offering non-invasive and computationally-efficient diagnostic tools. As adjunct methods for prenatal diagnosis, these tools can assist clinicians by reducing the need for unnecessary interventions and enabling earlier planning of management strategies for delivery.

Risk of placenta accreta spectrum following myomectomy: a nationwide cohort study

BACKGROUND

Whether myomectomy increases the risk of placenta accreta spectrum in the following pregnancies remains controversial.

OBJECTIVE

This study aimed to investigate the effect of myomectomy on the risk of placenta accreta spectrum in the following pregnancies. Moreover, different methods of myomectomy on the risk of placenta accreta spectrum were explored.

STUDY DESIGN

A nationwide cohort study was conducted using data from the Taiwan National Health Insurance Research Database, including all pregnant patients in Taiwan who gave birth between January 2008 and December 2017. A 1:1 propensity score estimation matching was performed for the analysis of myomectomy on the risk of placenta accreta spectrum. Among pregnant patients who received myomectomy, different methods of myomectomy on the risk of placenta accreta spectrum were compared with the control group.

RESULTS

Among the 1,371,458 pregnant patients in this study, 11,255 pregnant patients had a history of myomectomy. The risk of placenta accreta spectrum was higher in pregnant patients with a history of myomectomy than in pregnant patients without a history of myomectomy (incidence: 0.96% vs 0.20%; adjusted odds ratio, 2.28; 95% confidence interval, 1.85-2.81; P<.01). Among pregnant patients with a history of myomectomy, 5045 (46.87%) received laparotomic myomectomy, 3973 (36.93%) received laparoscopic myomectomy, and 1742 (16.20%) received hysteroscopic myomectomy. The incidence of placenta accreta spectrum was higher in the hysteroscopic group than in the laparotomic group or the laparoscopic group (1.89% [hysteroscopic group] vs 0.71% [laparotomic group] and 0.81% [laparoscopic group]; P<.05). Compared with patients without a history of myomectomy, the adjusted odds ratio for placenta accreta spectrum was 3.88 (95% confidence interval, 2.68-5.63; P<.05) in the hysteroscopic group.

CONCLUSION

Myomectomy, especially hysteroscopic myomectomy, is associated with an increased risk of placenta accreta spectrum in the subsequent pregnancy.

Plasma cell-free DNA as a monitoring tool for high-risk pregnancies associated with antiphospholipid syndrome

INTRODUCTION

Despite thromboprophylaxis, women with antiphospholipid syndrome (APS) face high-risk pregnancies due to proinflammatory and prothrombotic states. This highlights the need for new monitoring and prognostic tools. Recent insights into the pathophysiological role of neutrophil activation and extracellular trap (NET) formation in this syndrome led to the exploration of plasma cell-free DNA (cfDNA), a derivative of NETosis, as a promising biomarker.

MATERIALS AND METHODS

cfDNA was isolated and quantified from plasma samples of healthy pregnant women (control group, HC) and women with APS (APS group). We assessed the physiological variability of cfDNA across the three trimesters in HC. Levels of cfDNA were compared between APS and HC by gestational trimester. ROC curve analysis was performed to evaluate the efficacy of cfDNA levels for classifying APS patients. Furthermore, cfDNA levels in pregnant women with APS with obstetric complications were compared to those from uncomplicated pregnancies.

RESULTS

Among HC, cfDNA significantly increased in the third trimester compared to the first and second. Elevated cfDNA levels in APS compared to HC were observed in the first and second trimesters. First-trimester cfDNA levels demonstrated the highest classification ability to discriminate between APS and HC patients (AUC: 0.906). Among APS, those with complicated pregnancies (fetal growth restriction, preeclampsia, placenta accreta) exhibited significantly elevated cfDNA levels in the second trimester.

CONCLUSIONS

Elevated levels of cfDNA in pregnant women with APS, particularly among those with obstetric complications, supports further investigation into the potential of cfDNA as a valuable tool in the obstetric management of women with APS.

Prevalence of fetal anomalies, stillbirth, neonatal morbidity, or mortality in pregnancies complicated by placenta accreta spectrum disorders

INTRODUCTION

Placenta accreta spectrum disorders (PAS) lead to major complications in pregnancy. While the maternal morbidity associated with PAS is well known, there is less information regarding neonatal morbidity in this setting. The aim of this study is to describe the neonatal outcomes (fetal malformations, neonatal morbidity, twin births, stillbirth, and neonatal death), using an international multicenter database of PAS cases.

MATERIAL AND METHODS

This was a prospective, multicenter cohort study based on prospectively collected cases, using the international multicenter database of the International Society for PAS, carried out between January 2020 and June 2022 by 23 centers with experience in PAS care. All PAS cases were included, regardless of whether singleton or multiple pregnancies and were managed in each center according to their own protocols. Data were collected via chart review. Local Ethical Committee approval and Data Use Agreements were obtained according to local policies.

RESULTS

There were 315 pregnancies eligible for inclusion, with 12 twin pregnancies, comprising 329 fetuses/newborns; 2 cases were excluded due to inconsistency of data regarding fetal abnormalities. For the calculation of neonatal morbidity and mortality, all elective pregnancy terminations were excluded, hence 311 pregnancies with 323 newborns were analyzed. In our cohort, 3 neonates (0.93%) were stillborn; of the 320 newborns delivered, there were 10 cases (3.13%) of neonatal death. The prevalence of major congenital malformations was 4.64% (15/323 newborns), most commonly, cardiovascular, central nervous system, and gastrointestinal tract malformations. The overall prevalence of major neonatal morbidity in pregnancies complicated by PAS was 47/311 (15.1%). There were no stillbirths, neonatal deaths, or fetal malformations in reported twin gestations.

CONCLUSIONS

Although some outcomes may be too rare to detect within our cohort and data should be interpreted with caution, our observational data supports reassuring neonatal outcomes for women with PAS.

Evaluation of maternal serum protein biomarkers in the prenatal evaluation of placenta accreta spectrum: A systematic scoping review

INTRODUCTION

Placenta accreta spectrum (PAS) is an increasingly commonly reported condition due to the continuous increase in the rate of cesarean deliveries (CD) worldwide; however, the prenatal screening for pregnant patients at risk of PAS at birth remains limited, in particular when imaging expertise is not available.

MATERIAL AND METHODS

Two major electronic databases (MEDLINE and Embase) were searched electronically for articles published in English between October 1992 and January 2023 using combinations of the relevant medical subject heading terms and keywords. Two independent reviewers selected observational studies that provided data on one or more measurement of maternal blood-specific biomarker(s) during pregnancies with PAS at birth. PRISMA Extension for Scoping Review (PRISMA-ScR) was used to extract data and report results.

RESULTS

Of the 441 reviewed articles, 29 met the inclusion criteria reporting on 34 different biomarkers. 14 studies were retrospective and 15 prospective overall including 18 251 participants. Six studies had a cohort design and the remaining a case-control design. Wide clinical heterogeneity was found in the included studies. In eight studies, the samples were obtained in the first trimester; in five, the samples were collected on hospital admission for delivery; and in the rest, the samples were collected during the second and/or third trimester.

CONCLUSIONS

Measurements of serum biomarkers, some of which have been or are still used in screening for other pregnancy complications, could contribute to the prenatal evaluation of patients at risk of PAS at delivery; however, important evidence gaps were identified for suitable cutoffs for most biomarkers, variability of gestational age at sampling and the potential overlap of the marker values with other placental-related complications of pregnancy.

Intraoperative and Postoperative Outcomes of Pfannenstiel and Midline Skin Incisions in Placenta Accreta Spectrum Disorders: Single-Center Experience

Background: We compared Pfannenstiel and midline skin incisions for cesarean hysterectomy in women with confirmed Placenta Accreta Spectrum Disorders. Aims: A retrospective cohort study was conducted to evaluate the outcomes of Pfannenstiel and midline skin incisions in women undergoing cesarean section hysterectomy for suspected placenta accreta at Akdeniz University Hospital between January 2010 and February 2022. Histopathological confirmation was obtained for all cases. Demographic, perioperative, and postoperative data, along with neonatal outcomes, were extracted from the hospital's electronic database. Possible complaints related to the incision site or other issues (e.g., vaginal dryness or sexual life) were identified through telephone interviews. Subjects were stratified into Pfannenstiel and midline incision cohorts, with subsequent data comparison. Results: Data from 67 women with a histopathologically confirmed PAS diagnosis were analyzed. Of these, 49 (73.1%) underwent Pfannenstiel incision, and 18 (26.9%) had a midline skin incision. Incisions were based on the surgeon's experience. Pfannenstiel incision was more common in antepartum hemorrhage, preoperative hemorrhage, and emergency surgery (p = 0.02, p = 0.014, p = 0.002, respectively). Hypogastric artery ligation occurred in 30 cases (61.2%) in the Pfannenstiel group but none in the midline group. Cosmetic dissatisfaction and sexual problems were more prevalent in the midline group (p < 0.05, all). Preoperative and postoperative blood parameters, transfused blood products, and neonatal outcomes were similar between the two groups. Conclusions: Relaparotomy, bladder injury, blood loss, and need for blood transfusion were more prevalent in the Pfannenstiel group, while greater dissatisfaction with the incision was observed in the midline incision group. Midline incision seems to be more favorable in patients with Placenta Accreta Spectrum (PAS). Patients may be informed regarding the worse cosmetic outcomes and possible sexual problems related to vaginal dryness when midline laparotomy is planned. But before opting for a Pfannenstiel incision, patients should receive comprehensive information regarding the potential risks of relaparotomy and bladder injury.

Neonatal outcomes in pregnancies complicated by placenta accreta- a matched cohort study

PURPOSE

Pregnancies complicated by placenta accreta spectrum (PAS) are associated with severe maternal morbidities. The aim of this study is to describe the neonatal outcomes in pregnancies complicated with PAS compared with pregnancies not complicated by PAS.

METHODS

A retrospective cohort study conducted at a single tertiary center between 03/2011 and 01/2022, comparing women with PAS who underwent cesarean delivery (CD) to a matched control group of women without PAS who underwent CD. We evaluated the following adverse neonatal outcomes: umbilical artery pH < 7.0, umbilical artery base excess ≤ - 12, APGAR score < 7 at 5 min, neonatal intensive care unit (NICU) admission, mechanical ventilation, hypoxic ischemic encephalopathy, seizures and neonatal death. We also evaluated a composite adverse neonatal outcome, defined as the occurrence of at least one of the adverse neonatal outcomes described above. Multivariable regression analysis was used to determine which adverse neonatal outcome were independently associated with the presence of PAS.

RESULTS

265 women with PAS were included in the study group and were matched to 1382 controls. In the PAS group compared with controls, the rate of composite adverse neonatal outcomes was significantly higher (33.6% vs. 18.7%, respectively, p < 0.001). In a multivariable logistic regression analysis, Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

CONCLUSION

Neonates in PAS pregnancies had higher rates of adverse outcomes. Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

Cesarean hysterectomy for placenta accreta spectrum: Surgeon specialty-specific assessment

OBJECTIVE

To assess (i) clinical and pregnancy characteristics, (ii) patterns of surgical procedures, and (iii) surgical morbidity associated with cesarean hysterectomy for placenta accreta spectrum based on the specialty of the attending surgeon.

METHODS

The Premier Healthcare Database was queried retrospectively to study patients with placenta accreta spectrum who underwent cesarean delivery and concurrent hysterectomy from 2016 to 2020. Surgical morbidity was assessed with propensity score inverse probability of treatment weighting based on surgeon specialty for hysterectomy: general obstetrician-gynecologists, maternal-fetal medicine specialists, and gynecologic oncologists.

RESULTS

A total of 2240 cesarean hysterectomies were studies. The most common surgeon type was general obstetrician-gynecologist (n = 1534, 68.5%), followed by gynecologic oncologist (n = 532, 23.8%) and maternal-fetal medicine specialist (n = 174, 7.8%). Patients in the gynecologic oncologist group had the highest rate of placenta increta or percreta, followed by the maternal-fetal medicine specialist and general obstetrician-gynecologist groups (43.4%, 39.6%, and 30.6%, P < .001). In a propensity score-weighted model, measured surgical morbidity was similar across the three subspecialty groups, including hemorrhage / blood transfusion (59.4-63.7%), bladder injury (18.3-24.0%), ureteral injury (2.2-4.3%), shock (8.6-10.5%), and coagulopathy (3.3-7.4%) (all, P > .05). Among the cesarean hysterectomy performed by gynecologic oncologist, hemorrhage / transfusion rates remained substantial despite additional surgical procedures: tranexamic acid / ureteral stent (60.4%), tranexamic acid / endo-arterial procedure (76.2%), ureteral stent / endo-arterial procedure (51.6%), and all three procedures (55.4%). Tranexamic acid administration with ureteral stent placement was associated with decreased bladder injury (12.8% vs 23.8-32.2%, P < .001).

CONCLUSION

These data suggest that patient characteristics and surgical procedures related to cesarean hysterectomy for placenta accreta spectrum differ based on surgeon specialty. Gynecologic oncologists appear to manage more severe forms of placenta accreta spectrum. Regardless of surgeon's specialty, surgical morbidity of cesarean hysterectomy for placenta accreta spectrum is significant.

The MRI estimations of placental volume, T2 dark band volume, and cervical length correlate with massive hemorrhage in patients with placenta accreta spectrum disorders

PURPOSE

To identify whether placental volume, T2 dark band volume, and cervical length measured by MRI correlate with massive hemorrhage (MH) in patients with placenta accreta spectrum (PAS) disorders.

METHODS

A total of 163 pregnant women with PAS underwent preoperative MRI examination were divided into MH group and non-MH group. The placental volume, T2 dark band volume, and cervical length of PAS patients were measured and evaluated their ability to identify MH in patients with PAS.

RESULTS

Patients with MH had a significantly larger placental volume, larger T2 dark band volume, and shorter cervical length than patients without MH (all P < 0.001). Multivariable logistic regression showed that placental volume (> 890 cm3), T2 dark band volume (> 35 cm3), and cervical length (< 30 mm) were significant independent risk factor in identification of MH. In all PAS patients, a positive linear correlation was found between placental volume and amount of blood loss (r = 0.527), and between T2 dark band volume and amount of blood loss (r = 0.642), and a negative linear correlation was found between cervical length and amount of blood loss (r = - 0.597). When combined with the three MRI indicators, the sensitivity and specificity in identifying cases at high risk for MH were 91.638% and 94.051%, respectively, with area under the curve (AUC) of 0.923.

CONCLUSION

The placental volume, T2 dark band volume, and cervical length might be used to predict MH in patients with PAS.

Early first-trimester transvaginal ultrasound screening for cesarean scar pregnancy in patients with previous cesarean delivery: analysis of the evidence

Obstetric hemorrhage is a leading cause of maternal morbidity and mortality. An important etiology of obstetric hemorrhage is placenta accreta spectrum. In the last 2 decades, there has been increased clinical experience of the devastating effect of undiagnosed, as well as late diagnosed, cases of cesarean scar pregnancy. There is a growing body of evidence suggesting that cesarean scar pregnancy is an early precursor of second- and third-trimester placenta accreta spectrum. As such, cesarean scar pregnancy should be diagnosed in the early first trimester. This early diagnosis could be achieved by introducing regimented sonographic screening in pregnancies of patients with previous cesarean delivery. This opinion article evaluates the scientific and clinical basis of whether cesarean scar pregnancy, with special focus on its early first-trimester discovery, complies with the accepted requirements of a screening test. Each of the 10 classical screening criteria of Wilson and Jungner were systematically applied to evaluate if the criteria were met by cesarean scar pregnancy, to analyze if it is possible and realistic to carry out screening in a population-wide fashion.

Placental T2WI MRI-based radiomics-clinical nomogram predicts suspicious placenta accreta spectrum in patients with placenta previa

BACKGROUND

The incidence of placenta accreta spectrum (PAS) increases in women with placenta previa (PP). Many radiologists sometimes cannot completely and accurately diagnose PAS through the simple visual feature analysis of images, which can affect later treatment decisions. The study is to develop a T2WI MRI-based radiomics-clinical nomogram and evaluate its performance for non-invasive prediction of suspicious PAS in patients with PP.

METHODS

The preoperative MR images and related clinical data of 371 patients with PP were retrospectively collected from our hospital, and the intraoperative examination results were used as the reference standard of the PAS. Radiomics features were extracted from sagittal T2WI MR images and further selected by LASSO regression analysis. The radiomics score (Radscore) was calculated with logistic regression (LR) classifier. A nomogram integrating Radscore and selected clinical factors was also developed. The model performance was assessed with respect to discrimination, calibration and clinical usefulness.

RESULTS

A total of 6 radiomics features and 1 clinical factor were selected for model construction. The Radscore was significantly associated with suspicious PAS in both the training (p < 0.001) and validation (p < 0.001) datasets. The AUC of the nomogram was also higher than that of the Radscore in the training dataset (0.891 vs. 0.803, p < 0.001) and validation dataset (0.897 vs. 0.780, p < 0.001), respectively. The calibration was good, and the decision curve analysis demonstrated the nomogram had higher net benefit than the Radscore.

CONCLUSIONS

The T2WI MRI-based radiomics-clinical nomogram showed favorable diagnostic performance for predicting PAS in patients with PP, which could potentially facilitate the obstetricians for making clinical decisions.

Pregnancy Outcomes after Uterine Preservation Surgery for Placenta Accreta Spectrum: A Retrospective Cohort Study

OBJECTIVE

 This study aimed to investigate maternal and neonatal outcomes in subsequent pregnancies of women with a history of placenta accreta spectrum (PAS) compared with women without history of PAS.

STUDY DESIGN

 A retrospective cohort study conducted at a single tertiary center between March 2011 and January 2022. We compared women with a history of PAS who had uterine preservation surgery and a subsequent pregnancy, to a control group matched in a 1:5 ratio. The primary outcome was the occurrence of a composite adverse outcome (CAO) including any of the following: uterine dehiscence, uterine rupture, blood transfusion, hysterectomy, neonatal intensive care unit admission, and neonatal mechanical ventilation. Multivariable logistic regression was performed to evaluate associations with the CAO.

RESULTS

 During the study period, 287 (1.1%) women were diagnosed with PAS and delivered after 25 weeks of gestation. Of these, 32 (11.1%) women had a subsequent pregnancy that reached viability. These 32 women were matched to 139 controls. There were no significant differences in the baseline characteristics between the study and control groups. Compared with controls, the proportion of CAO was significantly higher in women with previous PAS pregnancy (40.6 vs. 19.4%, p = 0.019). In a multivariable logistic regression analysis, previous PAS (adjusted odds ratio [aOR] = 3.31, 95% confidence interval [CI] = 1.09-10.02, p = 0.034) and earlier gestational age at delivery (aOR = 3.53, 95% CI = 2.27-5.49, p < 0.001) were independently associated with CAOs.

CONCLUSION

 A history of PAS in a previous pregnancy is associated with increased risk of CAOs in subsequent pregnancies.

KEY POINTS

· The uterine-preserving approach for PAS delivery is gaining more attention and popularity in recent years.. · Women with a previous pregnancy with PAS had higher rates of CAOs in subsequent pregnancies.. · Previous PAS pregnancy is an independent factor associated with adverse outcomes..

Development and validation of a nomogram for predicting placenta accreta spectrum in pregnancies with one previous cesarean delivery

OBJECTIVE

This study aimed to develop and validate a prenatal nomogram to predict the risk of placenta accreta spectrum (PAS) in women with one previous cesarean delivery.

METHODS

This retrospective study enrolled 5157 pregnant women with one previous cesarean delivery in China from January 2021 to January 2023. The nomogram was developed from a training cohort of 3612 pregnant women and tested on a validation cohort of 1545 pregnant women. Multivariate regression analysis was performed using the minimum value of the Akaike information criterion to select prognostic factors that can be included in the nomogram. We evaluated the nomogram by the area under the receiver operating characteristic (ROC) curve, calibration curves, and the decision curve analysis (DCA).

RESULTS

PAS occurred in 199 (5.51%) and 80 (5.18%) patients in the training and validation cohorts, respectively. Backward stepwise algorithms in the multivariable logistic regression model determined abortion, hypertensive disorders complicating pregnancy, fetal position, and placenta previa as relevant PAS predictors. The area under the ROC curve for the nomogram was 0.770 (95% confidence interval [CI] 0.733-0.807) and 0.791 (95% CI 0.730-0.853) for the training and validation cohorts, respectively. The calibration curves indicated that the nomogram's prediction probability was consistent with the actual probability. The DCA curve revealed that the nomogram has potential clinical benefit.

CONCLUSION

A prenatal nomogram was developed for PAS in our study, which helped obstetricians determine potential patients with PAS and make sufficient preoperative preparation to reduce maternal and neonatal complications.

Single-cell and spatial transcriptomics reveal alterations in trophoblasts at invasion sites and disturbed myometrial immune microenvironment in placenta accreta spectrum disorders

BACKGROUND

Placenta accreta spectrum disorders (PAS) are a severe complication characterized by abnormal trophoblast invasion into the myometrium. The underlying mechanisms of PAS involve a complex interplay of various cell types and molecular pathways. Despite its significance, both the characteristics and intricate mechanisms of this condition remain poorly understood.

METHODS

Spatial transcriptomics (ST) and single-cell RNA sequencing (scRNA-seq), were performed on the tissue samples from four PAS patients, including invasive tissues (ST, n = 3; scRNA-seq, n = 4), non-invasive normal placenta samples (ST, n = 1; scRNA-seq, n = 2). Three healthy term pregnant women provided normal myometrium samples (ST, n = 1; scRNA-seq, n = 2). ST analysis characterized the spatial expression landscape, and scRNA-seq was used to identify specific cellular components in PAS. Immunofluorescence staining was conducted to validate the findings.

RESULTS

ST slices distinctly showed the myometrium in PAS was invaded by three subpopulations of trophoblast cells, extravillous trophoblast cells, cytotrophoblasts, and syncytiotrophoblasts, especially extravillous trophoblast cells. The pathways enriched by genes in trophoblasts, smooth muscle cells (SMC), and immune cells of PAS were mainly associated with immune and inflammation. We identified elevated expression of the angiogenesis-stimulating gene PTK2, alongside the cell proliferation-enhancing gene EGFR, within the trophoblasts of PAS group. Trophoblasts mainly contributed the enhancement of HLA-G and EBI3 signaling, which is crucial in establishing immune escape. Meanwhile, SMC regions in PAS exhibited upregulation of immunomodulatory markers such as CD274, HAVCR2, and IDO1, with CD274 expression experimentally verified to be increased in the invasive SMC areas of the PAS group.

CONCLUSIONS

This study provided information of cellular composition and spatial organization in PAS at single-cell and spatial level. The dysregulated expression of genes in PAS revealed a complex interplay between enhanced immune escape in trophoblasts and immune tolerance in SMCs during invasion in PAS. These findings will enhance our understanding of PAS pathogenesis for developing potential therapeutic strategies.

Can immunohistochemistry improve the pathological diagnosis of placenta accreta spectrum (PAS) disorders?

PURPOSE

The term of placenta accreta spectrum (PAS) disorder includes all grades of abnormal placentation. It is crucial for pathologist provide standardized diagnostic assessment to evaluate the outcome of management strategies. Moreover, a correct and safe diagnosis is useful in the medico-legal field when it becomes difficult for the gynecologist to demonstrate the suitability and legitimacy of demolitive treatment. The purposes of our study were: (1) to assess histopathologic features according to the recent guidelines; (2) to determine if immunohistochemistry can be useful to identify extravillous trophoblast (EVT) and to measure the depth of infiltration into the myometrium to improve the diagnosis of PAS.

METHODS

The retrospective study was conducted on 30 cases of gravid hysterectomy with histopathologic diagnosis of PAS. To identify the depth of EVT, immunohistochemical stainings were performed using anti MNF116 (cytokeratins 5, 6, 8, 17, 19), actin-SM, HPL (Human Placental Lactogen), vimentin and GATA3 antibodies.

RESULTS

Our cases were graded based on the degree of invasion of the myometrium. Ten were grade 1 (33.3%), 12 grade 2 (40%) and 8 grade 3A (26.7%). EVT invasion was best seen and evident by double immunostainings with actin-SM and cytokeratins, actin-SM and HPL, actin-SM and GATA3.

CONCLUSION

The role of pathologist is decisive to determine the different grades of PAS. A better understanding of the depth of myometrial invasion can be achieved by the use of immunohistochemistry affording an important tool to obtain reproducible grading of PAS. This purpose is crucial in the setting of postoperative quality reviews and particularly in the forensic medicine field.

Diffusion-derived vessel density (DDVD) computed from a simple diffusion MRI protocol as a biomarker of placental blood circulation in patients with placenta accreta spectrum disorders: A proof-of-concept study

OBJECTIVES

Increasing trend of PAS (placenta accreta spectrum disorders) incidence is a major health concern as PAS is associated with high maternal morbidity and mortality during cesarean section. Prenatal identification of PAS is crucial for delivery planning and patients management. This study aims to explore whether diffusion-derived vessel density (DDVD) computed from a simple diffusion MRI protocol differs in PAS from normal placenta.

METHODS

We enrolled 86 patients with PAS disorders and 40 pregnant women without PAS disorders. Each patient underwent intravoxel incoherent motion (IVIM) MRI sequence with 11 b-values. Placenta diffusion-derived vessel density (DDVD-b0b50) was the signal difference between b = 0 and b = 50 s/mm2 images. DDVD(b0b50) A/N was calculated as [accreta lesion DDVD(b0b50)]/ [normal placenta DDVD(b0b50)]. The correlation between DDVD and gestational age was explored using Spearman rank correlation. Differences of DDVD(b0b50) A/N in patients with normal placentas and with PAS, and in patients with different subtypes of PAS were explored.

RESULTS

DDVD was negatively correlated with gestational age (p = 0.023, r = -0.359) in patients with normal placentas. DDVD(b0b50) A/N was significantly higher in patients with PAS (median:1.16, mean: 1.261) than normal placenta (median:1.02, mean: 1.032, p < 0.001) and especially higher in patients with placenta increta (median:1.14, mean: 1.278) and percreta (median: 1.20, mean: 1.396, p < 0.001).

CONCLUSION

As a higher DDVD indicates higher physiological volume of micro-vessels in PAS, this study suggests DDVD can be a potential biomarker to evaluate the placenta perfusion.

Placenta accreta spectrum conservative management and coagulopathy: case series and systematic review

OBJECTIVE

Management of placenta accreta spectrum (PAS) with the placenta kept in situ aims to preserve fertility and minimize blood loss. However, this method is associated with a risk of coagulopathy and subsequent bleeding. The aim of this study was to evaluate the occurrence and pathophysiology of coagulopathy in cases of PAS managed conservatively.

METHODS

We reviewed our database for cases of PAS in which the placenta was kept in situ. In addition, we performed a systematic review of articles on PAS in which the placenta was left in situ and was complicated by coagulopathy. PubMed was searched for publications between 1980 and 2023. Our eligibility criteria included studies in which no additional interventions were performed other than keeping the placenta entirely in situ, and in which coagulopathy was reported.

RESULTS

After screening and selection of full-text articles, 10 studies were included in the review. A review of our databases yielded a case series of PAS managed conservatively with the placenta kept in situ. When adding our case series to the results of our systematic review, a total of 87 cases were found to have been managed conservatively, with 28 cases of coagulopathy. Of these, the time at which coagulopathy developed was known in 11 cases. The median time at development of coagulopathy was 58 (interquartile range, 50-67) days postpartum.

CONCLUSIONS

Our findings highlight that conservative management of PAS with the placenta in situ poses a risk of coagulopathy. Keeping the placenta in situ after delivery prolongs the risk factors that are integral to PAS. The pathophysiology behind coagulopathy is comparable with that of concealed placental abruption, due to the disrupted uteroplacental interface and the collection of blood in the placenta. Therefore, the presence of large placental lakes could be an indicator of developing coagulopathy. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Surgical treatment and reproductive outcomes in caesarean scar pregnancy at a single center

BACKGROUND

To investigate factors associated with different reproductive outcomes in patients with Caesarean scar pregnancies (CSPs).

METHODS

Between May 2017 and July 2022, 549 patients underwent ultrasound-guided uterine aspiration and laparoscopic scar repair at the Gynaecology Department of Hubei Maternal and Child Health Hospital. Ultrasound-guided uterine aspiration was performed in patients with type I and II CSPs, and laparoscopic scar repair was performed in patients with type III CSP. The reproductive outcomes of 100 patients with fertility needs were followed up and compared between the groups.

RESULTS

Of 100 patients, 43% had live births (43/100), 19% had abortions (19/100), 38% had secondary infertility (38/100), 15% had recurrent CSPs (RCSPs) (15/100). The reproductive outcomes of patients with CSPs after surgical treatment were not correlated with age, body mass index, time of gestation, yields, abortions, Caesarean sections, length of hospital stay, weeks of menopause during treatment, maximum diameter of the gestational sac, thickness of the remaining muscle layer of the uterine scar, type of CSP, surgical method, uterine artery embolisation during treatment, major bleeding, or presence of uterine adhesions after surgery. Abortion after treatment was the only risk factor affecting RCSPs (odds ratio 11.25, 95% confidence interval, 3.302-38.325; P < 0.01) and it had a certain predictive value for RCSP occurrence (area under the curve, 0.741).

CONCLUSIONS

The recurrence probability of CSPs was low, and women with childbearing intentions after CSPs should be encouraged to become pregnant again. Abortion after CSP is a risk factor for RCSP. No significant difference in reproductive outcomes was observed between the patients who underwent ultrasound-guided uterine aspiration and those who underwent laparoscopic scar repair for CSP.

Incidence of and factors associated with emergency caesarean section in pregnant women with gestational diabetes mellitus: A retrospective cohort study

AIM

The incidence of factors associated with emergency cesarean section (ECS) in patients with gestational diabetes mellitus (GDM) have not been well investigated.

METHODS

We conducted a retrospective cohort study of patients diagnosed with GDM between 2011 and 2020 at a tertiary care hospital in Japan. Clinical data, vital signs, and laboratory results of the patients were collected from electronic medical records. We constructed a multivariate logistic regression model to identify the clinical characteristics associated with ECS.

RESULTS

We included 1189 patients diagnosed with GDM, the mean maternal age was 33 years, and 507 (42.6%) patients were aged ≥35 years. In total, 114 patients underwent ECS (9.6%). The previous assisted reproductive technology (ART) use (odds ratio [OR], 1.81; 95% confidence interval [CI], 1.12-2.93), previous artificial abortion (OR, 1.94; 95% CI, 1.13-3.33), high pre-pregnancy body mass index (BMI) (OR, 1.07; 95% CI, 1.02-1.11), and late diagnosis of GDM (OR, 1.02; 95% CI, 1.003-1.05) were independently associated with ECS.

CONCLUSIONS

One of every 10 GDM patients required ECS. Previous ART use, previous artificial abortion, high pre-pregnancy BMI, and late diagnosis of GDM were risk factors for ECS in GDM patients.

Patient Perception of Care, Outcomes, and Consequences from Placenta Accreta Spectrum: A Survey-Based Study

OBJECTIVE

Placenta accreta spectrum (PAS) is an obstetric diagnosis that carries significant risks. However, little is known about patient perceptions of care. This study was conducted to describe the patient experience, reported outcomes, and assess geographical variation in PAS care in the United States.

STUDY DESIGN

Partnering with a PAS patient advocacy organization, we conducted an online survey of PAS patients. Perceptions of care and outcomes, and geographic variation were described.

RESULTS

We received 108 responses (69% response rate); 103 respondents delivered in the United States. Demographic characteristics were similar across each region. Most (67%) reported at least one prior cesarean delivery and 53% reported placenta previa in the PAS pregnancy. Over half (63%) reported an antenatal suspicion of PAS and 66% of those respondents reported changing their delivery hospital as a result of their antenatal diagnosis. Though not statistically significant, both showed variability across regions (both p ≥0.60). Seventy-five percent of respondents with antenatal diagnosis reported their pregnancy was managed by a dedicated PAS care team, which did not differ by region (p = 0.80). A majority of respondents (75%) felt their PAS care team was prepared for their delivery; this too did not vary across regions (p = 0.97). Many respondents reported at least one physical (63%) or mental health (17%) adverse outcome as a result of their PAS pregnancy.

CONCLUSION

As reported by prior PAS patients, perception of care and outcomes are overall favorable. There are long-term physical and mental adverse consequences reported. Geographical variation is mixed, however, national guidelines are predominately followed.

KEY POINTS

· Patient perceptions of care and outcomes are overall positive and favorable.. · Long lasting physical and mental health consequence from PAS pregnancies are commonly seen.. · Multidisciplinary care is widely adopted for PAS pregnancies..

Modified one-step conservative uterine surgery (MOSCUS) versus cesarean hysterectomy in the management of placenta accreta spectrum: A single-center retrospective analysis based on 619 Vietnamese pregnant women

OBJECTIVES

To compare maternal outcome measures in surgical management of placenta accreta spectrum (PAS)-the modified one-step conservative uterine surgery (MOSCUS), a new approach at Tu Du Hospital in Vietnam, versus cesarean hysterectomy, and to identify factors that appear to contribute to the successful outcome of the MOSCUS.

METHODS

This retrospective study was conducted at Tu Du Hospital in southern Vietnam between January 2019 and December 2020. The study enrolled all pregnant women at more than 28 weeks of pregnancy with a diagnosis of PAS who underwent either a cesarean hysterectomy or a uterus-preserving approach using the MOSCUS method.

RESULTS

The prevalence of PAS at our single tertiary referral hospital was 0.4% (619 PAS cases/132 518 births) in 2 years. Among 296 patients, the surgical time duration, estimated blood loss, and red blood cell transfusion in the MOSCUS group (n = 217) were all significantly less than in the cesarean hysterectomy group (n = 79) (152.72 ± 42.23 vs 185.13 ± 58.22 min, 1000 vs 1500 mL, and 500 vs 710 mL, respectively). Intraoperatively, the rate of visceral injuries in the hysterectomy group was higher than that in the MOSCUS group (P < 0.001). However, the rate of postoperative infection was higher in the MOSCUS group than in the cesarean hysterectomy group (P = 0.012). Of a total of 217 cases managed using the MOSCUS management, 24 required a secondary hysterectomy; the success rate was 88.9% (95% confidence interval [CI] 84.3%-93.1%). Some of the primary factors associated with the success of MOSCUS included maternal age less than 35 years, planned surgery, severity of PAS, and estimated blood loss during surgery (odds ratio [OR] 5.16, 95% CI 1.96-13.59; OR 3.05, 95% CI 1.08-8.62; OR 3.62, 95% CI 1.19-10.98; and OR 49.66, 95% CI 11.16-221.02, respectively; P < 0.05).

CONCLUSION

MOSCUS is an acceptable alternative to cesarean hysterectomy in many patients diagnosed with PAS. This new surgical management of PAS resulted in the preservation of the uterus, and a favorable outcome in nearly 9 out of 10 pregnant women. We believe that MOSCUS can be safely offered for the management of PAS in referral hospital settings.

Risk factors for placenta accreta spectrum in pregnancies conceived after frozen-thawed embryo transfer in a hormone replacement cycle

OBJECTIVE

Assisted reproductive technology (ART), especially frozen-thawed embryo transfer (FET) in a hormone replacement cycle (HRC), is a risk factor for placenta accreta spectrum (PAS). This study aimed to clarify the risk factors for PAS related to the maternal background and ART techniques in pregnancies achieved after FET in an HRC.

STUDY DESIGN

We performed a case-control study in two tertiary perinatal centres in Japan. Among 14,028 patients who delivered at ≥24 weeks of gestation or were transferred after delivery to two tertiary perinatal centres between 2010 and 2021, 972 conceived with ART and 13,056 conceived without ART. PAS was diagnosed on the basis of the FIGO classification for the clinical diagnosis of PAS or retained products of conception after delivery at ≥24 weeks of gestation. We excluded women with fresh embryo transfer, FET with a spontaneous ovulatory cycle, a donor oocyte cycle, and missing details of the ART treatment. Finally, among women who conceived after FET in an HRC, 62 with PAS and 340 without PAS were included in this study. Multivariate logistic regression models were used for case-control comparisons, with adjustment for maternal age at delivery, parity, endometriosis or adenomyosis, the number of previous uterine surgeries of caesarean section, myomectomy, endometrial polypectomy or endometrial curettage, placenta previa, the stage of transferred embryos, and endometrial thickness at the initiation of progestin administration.

RESULTS

PAS was associated with ≥2 previous uterine surgeries (adjusted odds ratio, 3.57; 95 % confidence interval, 1.60-7.97) and the stage of embryo transfer (blastocysts: adjusted odds ratio, 2.89; 95 % confidence interval, 1.15-7.26). In patients with <2 previous uterine surgeries, PAS was associated with an endometrial thickness of <7.0 mm (adjusted odds ratio, 5.18; 95 % confidence interval, 1.10-24.44).

CONCLUSION

Multiple uterine surgeries and the transfer of blastocysts are risk factors for PAS in pregnancies conceived after FET in an HRC. In women with <2 previous uterine surgeries, a thin endometrium before FET is also a risk factor for PAS in these pregnancies.

Magnetic Resonance Imaging-Based Radiomics Nomogram to Predict Intraoperative Hemorrhage of Placenta Previa

OBJECTIVE

Placenta previa (PP) is associated with intraoperative and postpartum hemorrhage, increased maternal morbidity and mortality. We aimed to develop a magnetic resonance imaging (MRI)-based nomogram to preoperative prediction of intraoperative hemorrhage (IPH) for PP.

STUDY DESIGN

A total of 125 PP pregnant women were divided into a training set (n = 80) and a validation set (n = 45). An MRI-based model was built for the classification of patients into IPH and non-IPH groups in a training set and a validation set. Multivariate nomograms were built according to radiomics features. Receiver operating characteristic (ROC) curve was used to assess the model. Predictive accuracy of nomogram were assessed by calibration plots and decision curve analysis.

RESULTS

In multivariate analysis, placenta position, placenta thickness, cervical blood sinus, and placental signals in the cervix were significantly independent predictors for IPH (all ps < 0.05). The MRI-based nomogram showed favorable discrimination between IPH and non-IPH groups. The calibration curve showed good agreement between the estimated and the actual probability of IPH. Decision curve analysis also showed a high clinical benefit across a wide range of probability thresholds. Area under the ROC curve was 0.918 (95% confidence interval [CI]: 0.857-0.979) in the training set and 0.866 (95% CI: 0.748-0.985) in the validation set by the combination of four MRI features.

CONCLUSION

The MRI-based nomograms might be a useful tool for the preoperative prediction of IPH outcomes for PP. Our study enables obstetricians to perform adequate preoperative evaluation to reduce blood loss and cesarean hysterectomy.

KEY POINTS

· MRI is an important method for preoperative assessment of the risk of placenta previa.. · MRI-based nomogram can assess the risk of intraoperative bleeding of placenta previa.. · MRI is helpful for more comprehensive evaluation of placenta previa and adequate preoperative preparation..

Association between adenomyosis and placenta accreta and mediation effect of assisted reproductive technology on the association: A nationwide observational study

OBJECTIVES

To investigate the association between adenomyosis and placenta accreta spectrum (PAS) and to evaluate the effect of assisted reproductive technology (ART) in mediating this association.

METHODS

We retrieved data for singleton women from the Japanese nationwide perinatal registry between 2013 and 2019, excluding women with a history of adenomyomectomy. To investigate the association between adenomyosis and PAS among women, we used a multivariable logistic regression model with multiple imputation for missing data. We evaluated mediation effect of ART including in vitro fertilization and intracytoplasmic sperm injection on the association between adenomyosis and PAS using causal mediation analysis based on the counterfactual approach.

RESULTS

Of 1 500 173 pregnant women, 1539 (0.10%) had adenomyosis. The number receiving ART was 489/1539 (31.8%) and 117 482/1 498 634 (7.8%) in women with and without adenomyosis, respectively. The proportion of women who developed PAS was 21/1539 (1.4%) in women with adenomyosis and 7530/1 498 634 (0.5%) in women without adenomyosis. Adenomyosis was significantly associated with PAS (odds ratio [OR] 1.95; 95% confidence interval [CI] 1.26-3.00; P = 0.002). Mediation analysis showed that OR of the total effect of adenomyosis on PAS was 1.98 (95% CI 1.13-3.04), OR of natural indirect effect (effect explained by ART) was 1.15 (95% CI 1.01-1.41), and OR of natural direct effect (effect unexplained by ART) was 1.72 (95% CI 0.86-2.82). The proportion mediated (natural indirect effect/total effect) was 26.5%. Adenomyosis was also significantly associated with PAS without previa (OR 1.96; 95% CI 1.23-3.13, P = 0.005).

CONCLUSION

Adenomyosis was significantly associated with PAS. ART mediated 26.5% of the association between adenomyosis and PAS.

Conservative management or cesarean hysterectomy for placenta accreta spectrum in middle-income countries: A systematic review and meta-analysis

BACKGROUND

Cesarean hysterectomy is a dominant and effective approach during delivery in patients with placenta accreta spectrum (PAS). However, as hysterectomy results in a loss of fertility, conservative management is an alternative approach. However, management selection may be affected by a country's overall economic level. Thus the preferred treatment for PAS generates controversy in middle-income countries.

OBJECTIVES

We aimed to compare conservative management and cesarean hysterectomy for managing PAS in middle-income countries.

SEARCH STRATEGY

China National Knowledge Infrastructure, Wanfang Med Online Databases, Cochrane Library, Ovid MEDLINE, PubMed, Web of Science, EMBASE, clinicaltrials.gov, and Scopus were searched from inception through to October 1, 2022.

SELECTION CRITERIA

We included studies that evaluated at least one complication comparing conservative management and hysterectomy. All cases were diagnosed with PAS prenatally and intraoperatively.

DATA COLLECTION AND ANALYSIS

The primary outcomes were blood loss, adjacent organ damage, and the incidence of hysterectomy. Descriptive analyses were conducted for studies that did not meet the meta-analysis criteria. A fixed-effects model was used for studies without heterogeneity and a random-effects model was used for studies with statistical heterogeneity.

MAIN RESULTS

In all, 11 observational studies were included, with 975 and 625 patients who underwent conservative management and cesarean hysterectomy, respectively. Conservative management was significantly associated with decreased blood loss and lower risks of adjacent organ injury and hysterectomy. Conservative management significantly reduced blood transfusions, hospitalization duration, operative time, intensive care unit admission rates, and infections. There were no significant differences in the risks of coagulopathy, thromboembolism, or reoperation.

CONCLUSION

Given short-term complications and future fertility preferences for patients, conservative management appears to effectively manage PAS in middle-income countries. Owing to low levels of evidence, high heterogeneity and insufficient long-term follow-up data, further detailed studies are warranted.

The Role of the Placental Enzyme Indoleamine 2,3-Dioxygenase in Normal and Abnormal Human Pregnancy

The biologically significant phenomenon that the fetus can survive immune attacks from the mother has been demonstrated in mammals. The survival mechanism depends on the fetus and placenta actively defending themselves against attacks by maternal T cells, achieved through the localized depletion of the amino acid L-tryptophan by an enzyme called indoleamine 2,3-dioxygenase. These findings were entirely unexpected and pose important questions regarding diseases related to human pregnancy and their prevention during human pregnancy. Specifically, the role of this mechanism, as discovered in mice, in humans remains unknown, as does the extent to which impaired activation of this process contributes to major clinical diseases in humans. We have, thus, elucidated several key aspects of this enzyme expressed in the human placenta both in normal and abnormal human pregnancy. The questions addressed in this brief review are as follows: (1) localization and characteristics of human placental indoleamine 2,3-dioxygenas; (2) overall tryptophan catabolism in human pregnancy and a comparison of indoleamine 2,3-dioxygenase expression levels between normal and pre-eclamptic pregnancy; (3) controlling trophoblast invasion by indoleamine 2,3-dioxygenase and its relation to the pathogenesis of placenta accrete spectrum.

The relationship between cervical length and area measurements evaluated by MRI and the amount of hemorrhage in PAS cases

BACKGROUND

Placenta accreta spectrum often leads to massive hemorrhage and even maternal shock and death. This study aims to identify whether cervical length and cervical area measured by magnetic resonance imaging correlate with massive hemorrhage in patients with placenta accreta spectrum.

METHODS

The study was conducted at our hospital, and 158 placenta previa patients with placenta accreta spectrum underwent preoperative magnetic resonance imaging examination were included. The cervical length and cervical area were measured and evaluated their ability to identify massive hemorrhage in patients with placenta accreta spectrum.

RESULTS

The cervical length and area in patients with massive hemorrhage were both significantly smaller than those in patients without massive hemorrhage. The results of multivariate analysis show that cervical length and cervical area were significantly associated with massive hemorrhage. In all patients, a negative linear was found between cervical length and amount of blood loss (r =-0.613), and between cervical area and amount of blood loss (r =-0.629). Combined with cervical length and cervical area, the sensitivity, specificity, and the area under the curve for the predictive massive hemorrhage were 88.618%, 90.209%, and 0.890, respectively.

CONCLUSION

The cervical length and area might be used to recognize massive hemorrhage in placenta previa patients with placenta accreta spectrum.

Placenta accreta spectrum disorder at single-cell resolution: a loss of boundary limits in the decidua and endothelium

BACKGROUND

Placenta accreta spectrum disorders are associated with severe maternal morbidity and mortality. Placenta accreta spectrum disorders involve excessive adherence of the placenta preventing separation at birth. Traditionally, this condition has been attributed to excessive trophoblast invasion; however, an alternative view is a fundamental defect in decidual biology.

OBJECTIVE

This study aimed to gain insights into the understanding of placenta accreta spectrum disorder by using single-cell and spatially resolved transcriptomics to characterize cellular heterogeneity at the maternal-fetal interface in placenta accreta spectrum disorders.

STUDY DESIGN

To assess cellular heterogeneity and the function of cell types, single-cell RNA sequencing and spatially resolved transcriptomics were used. A total of 12 placentas were included, 6 placentas with placenta accreta spectrum disorder and 6 controls. For each placenta with placenta accreta spectrum disorder, multiple biopsies were taken at the following sites: placenta accreta spectrum adherent and nonadherent sites in the same placenta. Of note, 2 platforms were used to generate libraries: the 10× Chromium and NanoString GeoMX Digital Spatial Profiler for single-cell and spatially resolved transcriptomes, respectively. Differential gene expression analysis was performed using a suite of bioinformatic tools (Seurat and GeoMxTools R packages). Correction for multiple testing was performed using Clipper. In situ hybridization was performed with RNAscope, and immunohistochemistry was used to assess protein expression.

RESULTS

In creating a placenta accreta cell atlas, there were dramatic difference in the transcriptional profile by site of biopsy between placenta accreta spectrum and controls. Most of the differences were noted at the site of adherence; however, differences existed within the placenta between the adherent and nonadherent site of the same placenta in placenta accreta. Among all cell types, the endothelial-stromal populations exhibited the greatest difference in gene expression, driven by changes in collagen genes, namely collagen type III alpha 1 chain (COL3A1), growth factors, epidermal growth factor-like protein 6 (EGFL6), and hepatocyte growth factor (HGF), and angiogenesis-related genes, namely delta-like noncanonical Notch ligand 1 (DLK1) and platelet endothelial cell adhesion molecule-1 (PECAM1). Intraplacental tropism (adherent versus non-adherent sites in the same placenta) was driven by differences in endothelial-stromal cells with notable differences in bone morphogenic protein 5 (BMP5) and osteopontin (SPP1) in the adherent vs nonadherent site of placenta accreta spectrum.

CONCLUSION

Placenta accreta spectrum disorders were characterized at single-cell resolution to gain insight into the pathophysiology of the disease. An atlas of the placenta at single cell resolution in accreta allows for understanding in the biology of the intimate maternal and fetal interaction. The contributions of stromal and endothelial cells were demonstrated through alterations in the extracellular matrix, growth factors, and angiogenesis. Transcriptional and protein changes in the stroma of placenta accreta spectrum shift the etiologic explanation away from "invasive trophoblast" to "loss of boundary limits" in the decidua. Gene targets identified in this study may be used to refine diagnostic assays in early pregnancy, track disease progression over time, and inform therapeutic discoveries.

Three-dimensional volume rendering ultrasound for assessing placenta accreta spectrum severity and discriminating it from simple scar dehiscence

BACKGROUND

Prenatal ultrasound discrimination between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta is challenging both prenatally and intraoperatively, which often leads to overtreatment. In addition, accurate prenatal prediction of surgical difficulty and morbidity in placenta accreta spectrum is difficult, which precludes appropriate multidisciplinary planning. The advent of advanced 3-dimensional volume rendering and contrast enhancement techniques in modern ultrasound systems provides a comprehensive prenatal assessment, revealing details that are not discernible in traditional 2-dimensional imaging.

OBJECTIVE

This study aimed to evaluate the use of 3-dimensional volume rendering ultrasound techniques in determining the severity of placenta accreta spectrum and distinguishing between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta.

STUDY DESIGN

A prospective, cohort study was conducted between July 2022 and July 2023 in the fetal medicine unit of Dr Soetomo Academic General Hospital, Surabaya, Indonesia. All pregnant individuals with anterior low-lying placenta or placenta previa with a previous caesarean section who were referred with suspicion of placenta accreta spectrum were consented and screened using the standardised 2-dimensional and Doppler ultrasound imaging. Additional 3-dimensional volumes were obtained from the sagittal section of the uterus with a filled urinary bladder. These were analyzed by rotating the region of interest to be perpendicular to the uterovesical interface. The primary outcomes were the clinical and histologic severity in the cases of placenta accreta spectrum and correct diagnosis of dehiscence with nonadherent placenta underneath. The strength of association between ultrasound and clinical outcomes was determined. Multivariate logistic regression analyses and diagnostic testing of accuracy were used to analyze the data.

RESULTS

A total of 70 patients (56 with placenta accreta spectrum and 14 with scar dehiscence) were included in the analysis. Multivariate logistic regression of all 2-dimensional and 3-dimensional signs revealed the 3-dimensional loss of clear zone (P<.001) and the presence of bridging vessels on 2-dimensional Doppler ultrasound (P=.027) as excellent predictors in differentiating scar dehiscence and placenta accreta spectrum. The 3-dimensional loss of clear zone demonstrated a high diagnostic accuracy with an area under the curve of 0.911 (95% confidence interval, 0.819-1.002), with a sensitivity of 89.3% (95% confidence interval, 78.1-95.97%) and specificity of 92.9% (95% confidence interval, 66.1-99.8%). The presence of bridging vessels on 2-dimensional Doppler demonstrated an area under the curve of 0.848 (95% confidence interval, 0.714-0.982) with a sensitivity of 91.1% (95% confidence interval, 80.4-97.0%) and specificity of 78.6% (95% confidence interval, 49.2-95.3%). A subgroup analysis among the placenta accreta spectrum group revealed that the presence of a 3-dimensional disrupted bladder serosa with obliteration of the vesicouterine space was associated with vesicouterine adherence (P<.001).

CONCLUSION

Three-dimensional volume rendering ultrasound is a promising tool for effective discrimination between scar dehiscence with underlying nonadherent placenta and placenta accreta spectrum. It also shows potential in predicting the clinical severity with urinary bladder involvement in cases of placenta accreta spectrum.

Perinatal outcomes comparison between neuraxial and general anesthesia in pregnant women with placenta accreta spectrum: a multicenter retrospective study

PURPOSE

We investigated the impact of anesthesia mode on perinatal outcomes in patients with placenta accreta spectrum (PAS) undergoing cesarean delivery and identified factors associated with adverse perinatal events.

METHODS

The multicenter retrospective analysis was conducted in patients with PAS who delivered at three medical centers. Patients were classified according to whether they received general anesthesia (GA) or neuraxial anesthesia (NA). We compared the basic clinical characteristics of patients in the pre-propensity score matching (PSM) and post-PSM cohorts and identified factors associated with a high risk of adverse maternal outcomes.

RESULTS

This study included a total of 425 patients, with 307 (72.2%) in the GA group and 118 (27.8%) in the NA group. After PSM, 162 patients were identified for analysis. In the post-matched cohort, the NA group exhibited shorter total operation time (P = 0.030) and postoperative length of hospital stay (P = 0.037). Additionally, the NA group experienced lower intraoperative blood loss (P < 0.001) and received fewer units of transfused packed red blood cells (PRBC) (P < 0.001). Multivariate logistic regression analysis indicated that GA (P < 0.001), emergency cesarean delivery (P = 0.010), vascular lacunae within the placenta (P < 0.001), hypervascularity of uterine-placental margin (P = 0.002), hypervascularity of the cervix (P = 0.014), and balloon placement in the abdominal aorta (P < 0.001) were associated with a high risk of adverse maternal events.

CONCLUSION

In comparison to GA, cesarean delivery with NA in PAS patients appears to be associated with reduced intraoperative blood loss, PRBC transfusion, operating duration, and postoperative hospital stay.

First-trimester 3D power Doppler imaging markers of utero-placental vascular development are associated with placental weight and diameter at birth: The Rotterdam Periconception Cohort

INTRODUCTION

Early utero-placental vascular development impacts placental development and function throughout pregnancy. We investigated whether impaired first-trimester utero-placental vascular development is associated with pathologic features of the postpartum placenta.

METHODS

In this prospective observational study of 65 ongoing pregnancies, we obtained three-dimensional power Doppler ultrasounds of the placenta at 7, 9 and 11 weeks of gestation. We applied VOCAL software to measure placental volume (PV), virtual reality based segmentation to measure utero-placental vascular volume (uPVV) and applied a skeletonization algorithm to generate the utero-placental vascular skeleton (uPVS). Vascular morphology was quantified by assigning a morphologic characteristic to each voxel in the uPVS (i.e. end-, bifurcation-, crossing- or vessel point). Following delivery, placentas were measured and histologically examined according to the Amsterdam criteria to assess maternal vascular malperfusion (MVM). We used linear mixed models to estimate trajectories of PV, uPVV and uPVS development. Multivariable linear regression analysis with adjustments for confounders was used to evaluate associations between PV, uPVV and uPVS development and features of the postpartum placenta.

RESULTS

We observed no associations between first-trimester PV development and measurements of the postpartum placenta. Increased first-trimester utero-placental vascular development, reflected by uPVV (β = 0.25 [0.01; 0.48]), uPVS end points (β = 0.25 [0.01; 0.48]), bifurcation points (β = 0.22 [0.05; 0.37]), crossing points (β = 0.29 [0.07; 0.52]) and vessel points (β = 0.09 [0.02; 0.17]) was positively associated with the postpartum placental diameter. uPVV was positively associated with postpartum placental weight. No associations were found with MVM.

DISCUSSION

Development of the first-trimester utero-placental vasculature is associated with postpartum placental size, whereas placental tissue development contributes to a lesser extent.

A sonographic endometrial thickness <7 mm in women undergoing in vitro fertilization increases the risk of placenta accreta spectrum

BACKGROUND

The prevalence of placenta accreta spectrum, a potentially life-threatening condition, has exhibited a significant global rise in recent decades. Effective screening methods and early identification strategies for placenta accreta spectrum could enable early treatment and improved outcomes. Endometrial thickness plays a crucial role in successful embryo implantation and favorable pregnancy outcomes. Extensive research has been conducted on the impact of endometrial thickness on assisted reproductive technology cycles, specifically in terms of pregnancy rates, live birth rates, and pregnancy loss rates. However, limited knowledge exists regarding the influence of endometrial thickness on placenta accreta spectrum.

OBJECTIVE

This study aimed to evaluate the association between preimplantation endometrial thickness and the occurrence of placenta accreta spectrum in women undergoing assisted reproductive technology cycles.

STUDY DESIGN

A total of 4637 women who had not undergone previous cesarean delivery and who conceived by in vitro fertilization or intracytoplasmic sperm injection-embryo transfer treatment and subsequently delivered at the Third Affiliated Hospital of Guangzhou Medical University between January 2008 and December 2020 were included in this study. To explore the relationship between endometrial thickness and placenta accreta spectrum, we used smooth curve fitting, threshold effect, and saturation effect analysis. Multivariate logistic regression analysis was performed to evaluate the independent association between endometrial thickness and placenta accreta spectrum while adjusting for potential confounding factors. Propensity score matching was performed to reduce the influence of bias and unmeasured confounders. Furthermore, we used causal mediation effect analysis to investigate the mediating role of endometrial thickness in the relationship between gravidity and ovarian stimulation protocol and the occurrence of placenta accreta spectrum.

RESULTS

Among the 4637 women included in this study, pregnancies with placenta accreta spectrum (159; 3.4%) had significantly thinner endometrial thickness (non-placenta accreta spectrum, 10.08±2.04 mm vs placenta accreta spectrum, 8.88±2.21 mm; P<.001) during the last ultrasound before embryo transfer. By using smooth curve fitting, it was found that changes in endometrial thickness had a significant effect on the incidence of placenta accreta spectrum up to a thickness of 10.9 mm, beyond which the effect plateaued. Then, the endometrial thickness was divided into the following 4 groups: ≤7, >7 to ≤10.9, >10.9 to ≤13, and >13 mm. The absolute rates of placenta accreta spectrum in each group were 11.91%, 3.73%, 1.35%, and 2.54%, respectively. Compared with women with an endometrial thickness from 10.9 to 13 mm, the odds of placenta accreta spectrum increased from an adjusted odds ratio of 2.27 (95% confidence interval, 1.33-3.86) for endometrial thickness from 7 to 10.9 mm to an adjusted odds ratio of 7.15 (95% confidence interval, 3.73-13.71) for endometrial thickness <7 mm after adjusting for potential confounding factors. Placenta previa remained as an independent risk factor for placenta accreta spectrum (adjusted odds ratio, 11.80; 95% confidence interval, 7.65-18.19). Moreover, endometrial thickness <7 mm was still an independent risk factor for placenta accreta spectrum (adjusted odds ratio, 3.91; 95% confidence interval, 1.57-9.73) in the matched cohort after PSM. Causal mediation analysis revealed that approximately 63.9% of the total effect of gravidity and 18.6% of the total effect of ovarian stimulation protocol on placenta accreta spectrum were mediated by endometrial thickness.

CONCLUSION

The findings of our study indicate that thin endometrial thickness is an independent risk factor for placenta accreta spectrum in women without previous cesarean delivery undergoing assisted reproductive technology treatment. The clinical significance of this risk factor is slightly lower than that of placenta previa. Furthermore, our results demonstrate that endometrial thickness plays a significant mediating role in the relationship between gravidity or ovarian stimulation protocol and placenta accreta spectrum.

Pregnancy-specific beta-1-glycoprotein 6 is a potential novel diagnostic biomarker of placenta accreta spectrum

Early diagnosis is essential for the safer perinatal management of placenta accreta spectrum (PAS). We used transcriptome analysis to investigate diagnostic maternal serum biomarkers and the mechanisms of PAS development. We analyzed eight formalin-fixed paraffin-embedded placental specimens from two placenta increta and three placenta percreta cases who underwent cesarean hysterectomy at Sapporo Medical University Hospital between 2013 and 2019. Invaded placental regions were isolated from the uterine myometrium and RNA was extracted. The transcriptome difference between normal placenta and PAS was analyzed by microarray analysis. The PAS group showed markedly decreased expression of placenta-specific genes such as LGALS13 and the pregnancy-specific beta-1-glycoprotein (PSG) family. Term enrichment analysis revealed changes in genes related to cellular protein catabolic process, female pregnancy, autophagy, and metabolism of lipids. From the highly dysregulated genes in the PAS group, we investigated the expression of PSG family members, which are secreted into the intervillous space and can be detected in maternal serum from the early stage of pregnancy. The gene expression level of PSG6 in particular was progressively decreased from placenta increta to percreta. The PSG family, especially PSG6, is a potential biomarker for PAS diagnosis.

Two-Compartment Perfusion MR IVIM Model to Investigate Normal and Pathological Placental Tissue

BACKGROUND

Perfusion and diffusion coexist in the placenta and can be altered by pathologies. The two-perfusion model, where f1 and, f2 are the perfusion-fraction of the fastest and slowest perfusion compartment, respectively, and D is the diffusion coefficient, may help differentiate between normal and impaired placentas.

PURPOSE

Investigate the potential of the two-perfusion IVIM model in differentiating between normal and abnormal placentas.

STUDY-TYPE

Retrospective, case-control.

POPULATION

43 normal pregnancy, 9 fetal-growth-restriction (FGR), 6 small-for-gestational-age (SGA), 4 accreta, 1 increta and 2 percreta placentas.

FIELD STRENGTH/SEQUENCE

Diffusion-weighted-echo planar imaging sequence at 1.5 T.

ASSESSMENT

Voxel-wise signal-correction and fitting-controls were used to avoid overfitting obtaining that two-perfusion model fitted the observed data better than the IVIM model (Akaike weight: 0.94). The two-perfusion parametric-maps were quantified from ROIs in the fetal and maternal placenta and in the accretion zone of accreta placentas. The diffusion coefficient D was evaluated using a b ≥ 200 sec/mm2 -mono-exponential decay fit. IVIM metrics were quantified to fix f1  + f2  = fIVIM .

STATISTICAL-TESTS

ANOVA with Dunn-Sidák's post-hoc correction and Cohen's d test were used to compare parameters between groups. Spearman's coefficient was evaluated to study the correlation between variables. A P-value<0.05 indicated a statistically significant difference.

RESULTS

There was a significant difference in f1 between FGR and SGA, and significant differences in f2 and fIVIM between normal and FGR. The percreta + increta group showed the highest f1 values (Cohen's d = -2.66). The f2 between normal and percreta + increta groups showed Cohen's d = 1.12. Conversely, fIVIM had a small effective size (Cohen's d = 0.32). In the accretion zone, a significant correlation was found between f2 and GA (ρ = 0.90) whereas a significant negative correlation was found between fIVIM and D (ρ = -0.37 in fetal and ρ = -0.56 in maternal side) and f2 and D (ρ = -0.38 in fetal and ρ = -0.51 in maternal side) in normal placentas.

CONCLUSION

The two-perfusion model provides complementary information to IVIM parameters that may be useful in identifying placenta impairment.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.

A new technique to preserve the uterus in patients with placenta accreta spectrum disorders

BACKGROUND

Placenta accreta spectrum disorders are associated with substantial maternal morbidity and mortality. Despite a preoperative diagnosis, the rate of complications remains high, and the condition is generally associated with the need for a hysterectomy.

OBJECTIVE

This study aimed to evaluate the outcomes of a new uterine-preserving technique (called the combined approach, including surgical hemostasis, bilateral ligation of the descending branches of the uterine arteries, and hemostatic external supraplacental stitch with the use of the Zhukovsky double-balloon tamponade in patients with placenta accreta spectrum disorders) during cesarean delivery in women with placenta accreta spectrum disorders vs the surgical technique used until 2014.

STUDY DESIGN

This retrospective cohort study included 147 patients with placenta accreta spectrum disorders who were divided into 2 groups: the study group (n=95) is to undergo cesarean delivery using the combined approach, and the control group (n=52) is to undergo the surgical technique used until 2014, which included bilateral uterine artery ligation, which is the transfusion of plasma, red blood cells, platelets, and protease inhibitors.

RESULTS

The volume of blood loss was 1.5-fold lower (P=.0010), the number of blood transfusions was 5.1-fold lower (P=.026), and the rate of bladder injuries was 19-fold lower (P=.012) in the study group than that in the control group. The duration of hospital stay after delivery was 4 days lesser (P=.001) and the number of hysterectomies was 4.5-fold lower in the study group than in the control group (P=.023). The study groups did not differ in terms of placenta accreta spectrum type.

CONCLUSION

The combined approach during cesarean delivery proved to be more effective than the surgical technique used until 2014 in reducing the number of hysterectomies, blood loss volume, number of blood transfusions, and duration of hospital stay in patients with placenta accreta spectrum disorders.

Unraveling the molecular mechanisms driving enhanced invasion capability of extravillous trophoblast cells: a comprehensive review

Precise extravillous trophoblast (EVT) invasion is crucial for successful placentation and pregnancy. This review focuses on elucidating the mechanisms that promote heightened EVT invasion. We comprehensively summarize the pivotal roles of hormones, angiogenesis, hypoxia, stress, the extracellular matrix microenvironment, epithelial-to-mesenchymal transition (EMT), immunity, inflammation, programmed cell death, epigenetic modifications, and microbiota in facilitating EVT invasion. The molecular mechanisms underlying enhanced EVT invasion may provide valuable insights into potential pathogenic mechanisms associated with diseases characterized by excessive invasion, such as the placenta accreta spectrum (PAS), thereby offering novel perspectives for managing pregnancy complications related to deficient EVT invasion.

Material properties of nonpregnant and pregnant human uterine layers

The uterus has critical biomechanical functions in pregnancy and undergoes dramatic material growth and remodeling from implantation to parturition. The intrinsic material properties of the human uterus and how they evolve in pregnancy are poorly understood. To address this knowledge gap and assess the heterogeneity of these tissues, the time-dependent material properties of all human uterine layers were measured with nanoindentation. The endometrium-decidua layer was found to be the least stiff, most viscous, and least permeable layer of the human uterus in nonpregnant and third-trimester pregnant tissues. In pregnancy, the endometrium-decidua becomes stiffer and less viscous with no material property changes observed in the myometrium or perimetrium. Additionally, uterine material properties did not significantly differ between third-trimester pregnant tissues with and without placenta accreta. The foundational data generated by this study will facilitate the development of physiologically accurate models of the human uterus to investigate gynecologic and obstetric disorders.

The effect of uterine closure technique on cesarean scar niche development after multiple cesarean deliveries

OBJECTIVES

To use saline infusion sonohysterography (SIS) to evaluate the effect of uterine closure technique on niche formation after multiple cesarean deliveries (CDs).

METHODS

Patients with at least one prior CD were evaluated for niche via SIS. Subgroups of any number repeat CD (>1 prior), lower-order CD (<4 prior), and higher-order CD (≥4 prior) were analyzed, stratifying by hysterotomy closure technique at last cesarean preceding imaging; techniques included Technique A (endometrium-free double-layer closure) and Technique B (single- or double-layer routine endo-myometrial closure). Niche defects were quantified (depth, length, width, and residual myometrial thickness). The primary outcome was clinically significant niche, defined as depth >2 mm. Statistical analysis was performed using chi-square, ANOVA, t-test, Kruskal-Wallis, and multiple logistic regression, with p-values of <0.05 were statistically significant.

RESULTS

A total of 172 post-cesarean SIS studies were reviewed: 105 after repeat CDs, 131 after lower-order CDs, and 41 after higher-order CDs. Technique A was associated with a shorter interval to imaging and more double-layer closures. Technique B was associated with more clinically significant niches across all subgroups, and these niches were significantly longer and deeper when present. Multiple logistic regression demonstrated a 5.6, 8.1, and 11-fold increased adjusted odds of clinically significant niche following Technique B closure in the repeat CD (p<0.01), lower-order CD (p<0.001), and higher-order CD (p=0.04) groups, respectively.

CONCLUSIONS

While multiple CDs are known to increase risk for niche defects and their sequelae, hysterotomy closure technique may help to reduce niche development and severity.

Deep Learning Radiomic Analysis of MRI Combined with Clinical Characteristics Diagnoses Placenta Accreta Spectrum and its Subtypes

BACKGROUND

Different placenta accreta spectrum (PAS) subtypes pose varying surgical risks to the parturient. Machine learning model has the potential to diagnose PAS disorder.

PURPOSE

To develop a cascaded deep semantic-radiomic-clinical (DRC) model for diagnosing PAS and its subtypes based on T2-weighted MRI.

STUDY TYPE

Retrospective.

POPULATION

361 pregnant women (mean age: 33.10 ± 4.37 years), suspected of PAS, divided into segment training cohort (N = 40), internal training cohort (N = 139), internal testing cohort (N = 60), and external testing cohort (N = 122).

FIELD STRENGTH/SEQUENCE

Coronal T2-weighted sequence at 1.5 T and 3.0 T.

ASSESSMENT

Clinical characteristics such as history of uterine surgery and the presence of placenta previa, complete placenta previa and dangerous placenta previa were extracted from clinical records. The DRC model (incorporating radiomics, deep semantic features, and clinical characteristics), a cumulative radiological score method performed by radiologists, and other models (including a radiomics and clinical, the clinical, radiomics and deep learning models) were developed for PAS disorder diagnosing (existence of PAS and its subtypes).

STATISTICAL TESTS

AUC, ACC, Student's t-test, the Mann-Whitney U test, chi-squared test, dice coefficient, intraclass correlation coefficients, least absolute shrinkage and selection operator regression, receiver operating characteristic curve, calibration curve with the Hosmer-Lemeshow test, decision curve analysis, DeLong test, and McNemar test. P < 0.05 indicated a significant difference.

RESULTS

In PAS diagnosis, the DRC-1 outperformed than other models (AUC = 0.850 and 0.841 in internal and external testing cohorts, respectively). In PAS subtype classification (abnormal adherent placenta and abnormal invasive placenta), DRC-2 model performed similarly with radiologists (P = 0.773 and 0.579 in the internal testing cohort and P = 0.429 and 0.874 in the external testing cohort, respectively).

DATA CONCLUSION

The DRC model offers efficiency and high diagnostic sensitivity in diagnosis, aiding in surgical planning.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Standard diffusion-weighted, diffusion kurtosis and intravoxel incoherent motion in differentiating invasive placentas

PURPOSE

To investigate the diagnostic value of monoexponential, biexponential, and diffusion kurtosis MR imaging (MRI) in distinguishing invasive placentas.

METHODS

A total of 53 patients with invasive placentas and 47 patients with noninvasive placentas undergoing conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) were retrospectively enrolled. The mean, minimum, and maximum parameters including the apparent diffusion coefficient (ADC) and exponential ADC (eADC) from standard DWI, diffusion kurtosis (MK), and diffusion coefficient (MD) from DKI and pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) from IVIM were measured and compared from the volumetric analysis. Receiver operating characteristics (ROC) curve and logistic regression analyses were conducted to evaluate the diagnostic efficiency of different diffusion parameters for distinguishing invasive placentas.

RESULTS

Comparisons between accreta lesions in patients with invasive placentas (AL) and lower 1/3 part of the placenta in patients with noninvasive placentas (LP) demonstrated that MD mean, D mean, and D* mean were significantly lower while ADC max and D max were significantly higher in invasive placentas (all p < 0.05). Multivariate analysis demonstrated that D mean, D max and D* mean differed significantly among all the studied parameters for invasive placentas. A combined use of these three parameters yielded an AUC of 0.86 with sensitivity, specificity, and accuracy of 84.91%, 76.60%, and 80%, respectively.

CONCLUSION

The combined use of different IVIM parameters is helpful in distinguishing invasive placentas.

A Deep Learning Pipeline Using Prior Knowledge for Automatic Evaluation of Placenta Accreta Spectrum Disorders With MRI

BACKGROUND

The diagnosis of prenatal placenta accreta spectrum (PAS) with magnetic resonance imaging (MRI) is highly dependent on radiologists' experience. A deep learning (DL) method using the prior knowledge that PAS-related signs are generally found along the utero-placental borderline (UPB) may help radiologists, especially those with less experience, to mitigate this issue.

PURPOSE

To develop a DL tool for antenatal diagnosis of PAS using T2-weighted MR images.

STUDY TYPE

Retrospective.

SUBJECTS

Five hundred and forty pregnant women with clinically suspected PAS disorders from two institutions, divided into training (409), internal test (103), and external test (28) datasets.

FIELD STRENGTH/SEQUENCE

Sagittal T2-weighted fast spin echo sequence at 1.5 T and 3 T.

ASSESSMENT

An nnU-Net was trained for placenta segmentation. The UPB straightening approach was used to extract the utero-placental boundary region. The UPB image was then fed into DenseNet-PAS for PAS diagnosis. DenseNet-PP learnt placental position information to improve the PAS diagnosis performance. Three radiologists with 8, 10, and 12 years of experience independently evaluated the images. Two radiologists marked the placenta tissue. Histopathological findings were the reference standard.

STATISTICAL TESTS

Area under the curve (AUC) was used to evaluate the classification. Dice coefficient evaluated the segmentation between radiologists and the model performance. The Mann-Whitney U-test or the chi-squared test assessed the significance of differences. Decision curve analysis was used to determine clinical effectiveness. DeLong's test was used to compare AUCs.

RESULTS

Of the 540 patients, 170 had PAS disorders confirmed by histopathology. The DL model using UPB images and placental position yielded the highest AUC of 0.860 and 0.897 in internal test and external test cohorts, respectively, significantly exceeding the performance of three radiologists (internal test AUC, 0.737-0.770).

DATA CONCLUSION

By extracting the UPB image, this fully automatic DL pipeline achieved high accuracy and may assist radiologists in PAS diagnosis using MRI.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Deep Learning Model Based on Multisequence MRI Images for Assessing Adverse Pregnancy Outcome in Placenta Accreta

BACKGROUND

Preoperative assessment of adverse outcomes risk in placenta accreta spectrum (PAS) disorders is of high clinical relevance for perioperative management and prognosis.

PURPOSE

To investigate the association of preoperative MRI multisequence images and adverse pregnancy outcomes by establishing a deep learning model in patients with PAS.

STUDY TYPE

Retrospective.

POPULATION

323 pregnant women (age from 20 to 46, the median age is 33), suspected of PAS, underwent MRI to assess the PAS, divided into the training (N = 227) and validation datasets (N = 96).

FIELD STRENGTH/SEQUENCE

1.5T scanner/fast imaging employing steady-state acquisition sequence and single shot fast spin echo sequence.

ASSESSMENT

Different deep learning models (i.e., with single MRI input sequence/two sequences/multisequence) were compared to assess the risk of adverse pregnancy outcomes, which defined as intraoperative bleeding ≥1500 mL and/or hysterectomy. Net reclassification improvement (NRI) was used for quantitative comparison of assessing adverse pregnancy outcome between different models.

STATISTICAL TESTS

The AUC, sensitivity, specificity, and accuracy were used for evaluation. The Shapiro-Wilk test and t-test were used. A P value of <0.05 was considered statistically significant.

RESULTS

215 cases were invasive placenta accreta (67.44% of them with adverse outcomes) and 108 cases were non-invasive placenta accreta (9.25% of them with adverse outcomes). The model with four sequences assessed adverse pregnancy outcomes with AUC of 0.8792 (95% CI, 0.8645-0.8939), with ACC of 85.93% (95%, 84.43%-87.43%), with SEN of 86.24% (95% CI, 82.46%-90.02%), and with SPC of 85.62% (95%, 82.00%-89.23%) on the test cohort. The performance of model with four sequences improved above 0.10 comparing with that of model with two sequences and above 0.20 comparing with that of model with single sequence in terms of NRI.

DATA CONCLUSION

The proposed model showed good diagnostic performance for assessing adverse pregnancy outcomes.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Placental lakes vs lacunae: spot the differences

Sonographic sonolucencies are anechoic areas surrounded by tissue of normal echogenicity, commonly found in the placental parenchyma during the second and third trimesters of pregnancy. The ultrasound appearance of lakes and lacunae derives from the low echogenicity of villous-free areas within the placental parenchyma, filled with maternal blood of varying velocities. In normal placentation, lakes usually start appearing as soon as maternal blood begins to flow freely within the intervillous space at the end of the first trimester, whereas, in accreta placentation, lacunae develop progressively during the second trimester. Larger lakes are found mainly in areas of lower villous density under the fetal plate or in the marginal areas, but can also be found in the center of a lobule above the entry of a spiral artery. Lakes of variable size, position and shape are of no clinical significance, except if they transform into echogenic cystic lesions, which have been associated with poor fetal growth and placental malperfusion. Lacunae are formed by the distortion of one or more placental lobules developing inside a uterine scar, resulting from high-volume, high-velocity flows from the radial/arcuate arteries, and are associated with a high probability of placenta accreta spectrum at birth. They often present with ultrasound signs of uterine remodeling following scarring. Lakes and lacunae can coexist within the same placenta and both will change in size and shape as pregnancy advances. Better understanding of the etiopathology of placental sonolucent spaces and associated morphological changes is necessary to identify patients at risk of subsequent complications during pregnancy and/or at delivery. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Placenta Accreta Spectrum: Evaluation of classic and non-classic presentations, pathologic grading, and uterine scar dehiscence features in a modern institutional series

INTRODUCTION

The aim of this study is to document the distribution of classic versus non-classic presentation of Placenta Accreta Spectrum (PAS) disorders as well as grading categories by the Society for Pediatric Pathology (SPP) and FIGO systems in an institutional cohort of gravid hysterectomies. We also document the prevalence of uterine scar as a histologic correlate for uterine scar dehiscence, a phenomenon raised by some as central to PAS pathogenesis.

METHODS

PAS cases were assigned grade and designated as classic (anterior lower uterine segment implantation, prior C-section) or non-classic (implantation away from anterior lower uterine segment and/or no prior C-section). Features of dehiscence (uterine window, histologic evidence of scar) were recorded.

RESULTS

Sixty-two patients were included: 76 % had prior C-section; 55 % had other forms of uterine instrumentation. Classic PAS was recorded in 52 % patients; notably, 48 % had non-classic presentation; of these, all but one had prior instrumentation (curettage, myomectomy, laparoscopy). Uterine window was described in 53 % classic and 23 % non-classic PAS. Scar was demonstrated in 31 % classic and 23 % non-classic PAS; trichrome/reticulin stains were confirmatory. 32 % cases were SPP grade 1, 18 % grade 2, 18 % grade 3a and 32 % grade 3d. Grade 3 was significantly more common in classic (72 %) than non-classic (27 %) PAS.

DISCUSSION

While most PAS patients have classic presentation, a large subset does not; in addition, scar tissue is not identified histologically in most PAS hysterectomies; in these settings, PAS cannot be fully attributed to scar dehiscence. Uterine instrumentation often precedes non-classic PAS reinforcing the concept of decidual disruption as central to PAS pathogenesis. PAS grading as defined correlates with presentation (classic vs non-classic).

Placental volume as a novel sign for identifying placenta accreta spectrum in pregnancies with complete placenta previa

BACKGROUND

Placenta accreta spectrum (PAS) carries an increased risk of maternal-fetal mortality and morbidity, and magnetic resonance imaging (MRI) features for PAS have been used for preoperative identification. This study aims to investigate the role of placental volume evaluated by MRI in identifying PAS in pregnant women with complete placenta previa.

METHODS

Totally 163 cases of complete placenta previa pregnant women with a history of cesarean section underwent MRI for suspected PAS were included. We categorized the patients into two groups according to the presence or absence of PAS, and the maternal-fetal perinatal outcomes and placental volume analyzed by 3D Slice software were compared.

RESULTS

There were significantly more gravidity, parity, and number of previous cesarean delivery in the PAS group (P < 0.05). Significant differences were also found between the two groups with respect to the following baseline characteristics: gestational age at delivery, intraoperative blood loss, blood transfusion, and neonatal birth weight (P < 0.05). Of 163 women in the study, 7 (4.294%) required cesarean hysterectomy for high-grade PAS or pernicious bleeding during cesarean section, and PAS was confirmed with histologic confirmation in 6 (85.714%) cases. The placental volume in PAS group was greater than that in the non-PAS group (P < 0.05). With a threshold of more than 887 cm3, the sensitivity and specificity in identifying PAS were 85.531% and 83.907% respectively, with AUC 0.908 (95% CI: 0.853-0.948).

CONCLUSIONS

Placental volume may be a promising indicator of PAS in complete placenta previa patients with a history of cesarean section.

Diagnostic Role of Cell-Free miRNAs in Identifying Placenta Accreta Spectrum during First-Trimester Screening

Placenta accreta spectrum (PAS) is a severe complication of pregnancy associated with excessive invasion of cytotrophoblast cells at the sites of the endometrial-myometrial interface and the myometrium itself in cases of adherent (creta) and invasive (increta and percreta) forms, respectively. This leads to a high risk of massive blood loss, maternal hysterectomy, and preterm birth. Despite advancements in ultrasound protocols and found associations of alpha-fetoprotein, PAPP-A, hCG, PLGF, sFlt-1, IL-8, and IL-33 peripheral blood levels with PAS, there is a high need for an additional non-invasive test to improve the diagnostic accuracy and to select the real PAS from the suspected ones in the first-trimester screening. miRNA signatures of placental tissue, myometrium, and blood plasma from women with PAS in the third trimester of pregnancy, as well as miRNA profiles in exosomes from the blood serum of women in the first trimester with physiologically progressing pregnancy, complicated by PAS or pre-eclampsia, were obtained using deep sequencing. Two logistic regression models were constructed, both featuring statistically significant parameters related to the levels of miR-26a-5p, miR-17-5p, and miR-101-3p, quantified by real-time PCR in native blood serum. These models demonstrated 100% sensitivity in detecting PAS during the first pregnancy screening. These miRNAs were identified as specific markers for PAS, showing significant differences in their blood serum levels during the first trimester in the PAS group compared to those in physiological pregnancies, early- or late-onset pre-eclampsia groups. Furthermore, these miRNAs exhibited differential expression in the PAS placenta and/or myometrium in the third trimester and, according to data from the literature, control angiogenesis. Significant correlations were found between extracellular hsa-miR-101-3p and nuchal translucency thickness, hsa-miR-17-5p and uterine artery pulsatility index, and hsa-miR-26a-5p and hsa-miR-17-5p with PLGF. The developed test system for early non-invasive PAS diagnosis based on the blood serum level of extracellular miR-26a-5p, miR-17-5p, and miR-101-3p can serve as an auxiliary method for first-trimester screening of pregnant women, subject to validation with independent test samples.