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

Placenta Accreta Spectrum

Placenta accreta spectrum (PAS) is one of the most dangerous conditions in pregnancy and is increasing in frequency. The risk of life-threatening bleeding is present throughout pregnancy but is particularly high at the time of delivery. Although the exact cause is unknown, the result is clear: Severe PAS distorts the uterus and surrounding anatomy and transforms the pelvis into an extremely high-flow vascular state. Screening for risk factors and assessing placental location by antenatal ultrasonography are essential for timely diagnosis. Further evaluation and confirmation of PAS are best performed in referral centers with expertise in antenatal imaging and surgical management of PAS. In the United States, cesarean hysterectomy with the placenta left in situ after delivery of the fetus is the most common treatment for PAS, but even in experienced referral centers, this treatment is often morbid, resulting in prolonged surgery, intraoperative injury to the urinary tract, blood transfusion, and admission to the intensive care unit. Postsurgical complications include high rates of posttraumatic stress disorder, pelvic pain, decreased quality of life, and depression. Team-based, patient-centered, evidence-based care from diagnosis to full recovery is needed to optimally manage this potentially deadly disorder. In a field that has relied mainly on expert opinion, more research is needed to explore alternative treatments and adjunctive surgical approaches to reduce blood loss and postoperative complications.

The Need for Presurgical Evaluation for Placenta Accreta Spectrum

Staging or grading of placenta accreta spectrum has historically relied on histopathologic evaluation of placental and uterine specimens. This approach has limited utility, since it is retrospective in nature and does not allow for presurgical planning. Here, we argue for a paradigm shift to use of clinical and imaging characteristics to define the presurgical stage. We summarize past attempts at staging, and define a new data-driven approach to determining the stage prior to delivery. Use of this model may help hospitals direct patients to the most appropriate level of care for workup and management of placenta accreta spectrum. KEY POINTS: · Staging systems that rely on histopathologic grade (accreta, increta, percreta) are unhelpful in antenatal planning for placenta accreta spectrum.. · Past attempts at pre-delivery (pre-surgical) staging have failed to account for key factors that contribute to risk and morbidity.. · We developed a data-driven model that could be easily incorporated as a decision aid into clinical practice to help clinicians decide an individual patient's risk for placenta accreta spectrum..

Knowledge Gaps in Placenta Accreta Spectrum

Since its first description early in the 20th Century, placenta accreta and its variants have changed substantially in incidence, risk factor profile, clinical presentation, diagnosis and management. While systematic use of diagnostic tools and a multidisciplinary team care approach has begun to improve patient outcomes, the condition's pathophysiology, epidemiology, and best practices for diagnosis and management remain poorly understood. The use of large databases with broadly accepted terminology and diagnostic criteria should accelerate research in this area. Future work should focus on non-traditional phenotypes, such as those without placenta previa-preventive strategies, and long term medical and emotional support for patients facing this diagnosis. KEY POINTS: · Placenta accreta spectrum research may be improved with standardized terminology and use of large databases.. · Placenta accreta prediction should move beyond ultrasound with the addition of biomarkers, and needs to extend to those without traditional risk factors.. · Future research should identify practices that can prevent future accreta development..

Placenta accreta spectrum in major placenta previa diagnosed only by MRI: incidence, risk factors, and maternal morbidity

BACKGROUND

Antenatal assessment of maternal risk factors and imaging evaluation can help in diagnosis and treatment of placenta accreta spectrum (PAS) in major placenta previa (PP). Recent evidence suggests that magnetic resonance imaging (MRI) could complement ultrasonography (US) in the PAS diagnosis.

OBJECTIVES

Evaluate the incidence, risk factors, and maternal morbidity related to the MRI diagnosis of PAS in major PP.

DESIGN

A 10-year retrospective cohort study.

SETTING

Tertiary care hospital.

PATIENTS AND METHODS

We report on patients with major PP who had cesarean delivery in Abha Maternity and Children's Hospital (AMCH) over a 10-year period (2012-2021). They were evaluated with ultrasonography (US) and color Doppler for evidence of PAS. Antenatal MRI was ordered either to confirm the diagnosis (if equivocal US) or to assess the depth of invasion/extra-uterine extension (if definitive US).

MAIN OUTCOME MEASURES

Risk factors for PAS in major PP and maternal complications.

SAMPLE SIZE

299 patients RESULTS: Among 299 patients, MRI confirmed the PAS diagnosis in 91/299 (30.5%) patients. The independent risk factors for MRI diagnosis of PAS in major PP included only repeated cesarean sections and advanced maternal age. The commonest maternal morbidity in major PP with PAS was significantly excessive intraoperative bleeding.

CONCLUSION

MRI may be a valuable adjunct in the evaluation of PAS in major PP; as a complement, but not substitute US. MRI may be suitable in major PP/PAS patients who are older and have repeated cesarean deliveries with equivocal results or deep/extra-uterine extension on US.

LIMITATION

Single center, small sample size, lack of complete histopathological diagnosis.

CONFLICT OF INTEREST

None.

Placenta Accreta Spectrum and Postpartum Hemorrhage

Placenta accreta spectrum is a group of disorders involving abnormal trophoblastic invasion to the deep layers of endometrium and myometrium. Placenta accrete spectrum is one of the major causes of severe maternal morbidity, with increasing incidence in the past decade mainly secondary to an increase in cesarean deliveries. Severity varies depending on the depth of invasion, with the most severe form, known as percreta, invading uterine serosa or surrounding pelvic organs. Diagnosis is usually achieved by ultrasound, and MRI is sometimes used to assess invasion. Management usually involves a hysterectomy at the time of delivery. Other strategies include delayed hysterectomy or expectant management.

Mediation effect of pregnancy-induced hypertension on the association between assisted reproductive technology and adverse neonatal outcomes: a population-based study

BACKGROUND

Assisted reproductive technology (ART) has been widely used in the treatment of infertility, and is associated with adverse maternal and neonatal outcomes. However, the potential pathways by which ART affects adverse neonatal outcomes are unclear. We aimed to investigate the role of pregnancy-induced hypertension (PIH) in the association between ART and adverse neonatal outcomes.

METHODS

Adult women (aged ≥ 18 years) with a singleton pregnancy in the National Vital Statistics System (NVSS) 2020 were enrolled in this retrospective cohort study. Study outcomes were adverse neonatal outcomes, including premature birth, low birth weight, and admission to the neonatal intensive care unit (NICU). Logistic regression models were utilized to investigate the association between ART, PIH, and adverse neonatal outcomes, expressed as odds ratio (OR) and 95% confidence interval (CI). The distribution-of-the-product method was used to explore whether there was a mediating effect of PIH between ART and adverse neonatal outcomes, and the 95% CI of the distribution-of-the-product did not contain 0 indicating a mediating effect.

RESULTS

This study included 2,824,418 women, of whom 35,020 (1.24%) women used ART, 239,588 (8.48%) women had PIH, and 424,741 (15.04%) neonates had any adverse neonatal outcomes. The use of ART was associated with higher odds of PIH (OR = 1.42; 95%CI: 1.37-1.46) and any adverse neonatal outcomes (OR = 1.47; 95%CI: 1.43-1.51). The distribution-of-the-product was 0.31 (95%CI: 0.28-0.34), and 8.51% of the association between ART and adverse neonatal outcomes was mediated through PIH. Among different adverse neonatal outcomes, PIH mediated 29.17% of the association between ART and low birth weight, 9.37% of the association between ART and premature birth, and 12.20% of the association between ART and NICU admission. The mediating effect of PIH was found in women of different ages (< 35 years and ≥ 35 years) and parities (primipara and multipara).

CONCLUSION

This study supports a mediating role for PIH in the association between ART and adverse neonatal outcomes. Further studies are needed to determine the mechanisms by which AR affects PIH so that interventions to reduce PIH can be developed to reduce adverse neonatal outcomes associated with ART.

Differentiation of placenta percreta through MRI features and diffusion-weighted magnetic resonance imaging

OBJECTIVES

To identify whether parameters measured from diffusion kurtosis and intravoxel incoherent motion help diagnose placenta percreta.

METHODS

We retrospectively enrolled 75 patients with PAS disorders including 13 patients with placenta percreta and 40 patients without PAS disorders. Each patients underwent diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI). The apparent diffusion coefficient (ADC), perfusion fraction (f), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), mean diffusion kurtosis (MK) and mean diffusion coefficient (MD) were measured by the volumetric analysis and compared. MRI features were also analyzed and compared. The receiver operating characteristic (ROC) curve and logistic regression analysis were used to evaluate the diagnostic efficiency of different diffusion parameters and MRI features for distinguishing placental percreta.

RESULTS

D* was an independent risk factor from DWI for predicting placenta percreta with sensitivity of 73% and specificity of 76%. Focal exophytic mass remained as independent risk factor from MRI features for predicting placenta percreta with sensitivity of 72.7% and specificity of 88.1%. When the two risk factors were combined together, the AUC was the highest, 0.880 (95% CI 0.8-0.96).

CONCLUSION

D* and focal exophytic mass were associated with placenta percreta. A combination of the 2 risk factors can be used to predict placenta percreta.

CRITICAL RELEVANCE STATEMENT

A combination of D* and focal exophytic mass can be used to differentiate placenta percreta.

Efficacy of resuscitative endovascular balloon occlusion of the aorta for hemorrhage control in patients with abnormally invasive placenta: a historical cohort study

BACKGROUND

Patients with abnormally invasive placenta (AIP) are at high risk of massive postpartum hemorrhage. Resuscitative endovascular balloon occlusion of the aorta (REBOA), as an adjunct therapeutic strategy for hemostasis, offers the obstetrician an alternative for treating patients with AIP. This study aimed to evaluate the role of REBOA in hemorrhage control in patients with AIP.

METHODS

This was a historical cohort study with prospectively collected data between January 2014 to July 2021 at a single tertiary center. According to delivery management, 364 singleton pregnant AIP patients desiring uterus preservation were separated into two groups. The study group (balloon group, n = 278) underwent REBOA during cesarean section, whereas the reference group (n = 86) did not undergo REBOA. Surgical details and maternal outcomes were collected. The primary outcome was estimated blood loss and the rate of uterine preservation.

RESULTS

A total of 278 (76.4%) participants experienced REBOA during cesarean section. The patients in the balloon group had a smaller blood loss during cesarean Sect. (1370.5 [752.0] ml vs. 3536.8 [1383.2] ml; P < .001) and had their uterus salvaged more often (264 [95.0%] vs. 23 [26.7%]; P < .001). These patients were also less likely to be admitted to the intensive care unit after delivery (168 [60.4%] vs. 67 [77.9%]; P = .003) and had a shorter operating time (96.3 [37.6] min vs. 160.6 [45.5] min; P < .001). The rate of neonatal intensive care unit admission (176 [63.3%] vs. 52 [60.4%]; P = .70) and total maternal medical costs ($4925.4 [1740.7] vs. $5083.2 [1705.1]; P = .13) did not differ between the two groups.

CONCLUSIONS

As a robust hemorrhage-control technique, REBOA can reduce intraoperative hemorrhage in patients with AIP. The next step is identifying associated risk factors and defining REBOA inclusion criteria to identify the subgroups of AIP patients who may benefit more.

Animal models of the placenta accreta spectrum: current status and further perspectives

Placenta accreta spectrum disorder (PAS) is a kind of disease of placentation defined as abnormal trophoblast invasion of part or all of the placenta into the myometrium, even penetrating the uterus. Decidual deficiency, abnormal vascular remodeling in the maternal-fetal interface, and excessive invasion by extravillous trophoblast (EVT) cells contribute to its onset. However, the mechanisms and signaling pathways underlying such phenotypes are not fully understood, partly due to the lack of suitable experimental animal models. Appropriate animal models will facilitate the comprehensive and systematic elucidation of the pathogenesis of PAS. Due to the remarkably similar functional placental villous units and hemochorial placentation to humans, the current animal models of PAS are based on mice. There are various mouse models induced by uterine surgery to simulate different phenotypes of PAS, such as excessive invasion of EVT or immune disturbance at the maternal-fetal interface, which could define the pathological mechanism of PAS from the perspective of the "soil." Additionally, genetically modified mouse models could be used to study PAS, which is helpful to exploring the pathogenesis of PAS from the perspectives of both "soil" and "seed," respectively. This review details early placental development in mice, with a focus on the approaches of PAS modeling. Additionally, the strengths, limitations and the applicability of each strategy and further perspectives are summarized to provide the theoretical foundation for researchers to select appropriate animal models for various research purposes. This will help better determine the pathogenesis of PAS and even promote possible therapy.

Biomolecules Involved in Both Metastasis and Placenta Accreta Spectrum-Does the Common Pathophysiological Pathway Exist?

The process of epithelial-to-mesenchymal transition (EMT) is crucial in the implantation of the blastocyst and subsequent placental development. The trophoblast, consisting of villous and extravillous zones, plays different roles in these processes. Pathological states, such as placenta accreta spectrum (PAS), can arise due to dysfunction of the trophoblast or defective decidualization, leading to maternal and fetal morbidity and mortality. Studies have drawn parallels between placentation and carcinogenesis, with both processes involving EMT and the establishment of a microenvironment that facilitates invasion and infiltration. This article presents a review of molecular biomarkers involved in both the microenvironment of tumors and placental cells, including placental growth factor (PlGF), vascular endothelial growth factor (VEGF), E-cadherin (CDH1), laminin γ2 (LAMC2), the zinc finger E-box-binding homeobox (ZEB) proteins, αVβ3 integrin, transforming growth factor β (TGF-β), β-catenin, cofilin-1 (CFL-1), and interleukin-35 (IL-35). Understanding the similarities and differences in these processes may provide insights into the development of therapeutic options for both PAS and metastatic cancer.

The prenatal diagnostic indicators of placenta accreta spectrum disorders

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

Nomogram to predict postpartum hemorrhage in cesarean delivery for twin pregnancies: a retrospective cohort study in China

Background

Postpartum hemorrhage (PPH) is the most common cause of maternal morbidity and mortality worldwide. A reliable risk assessment tool for PPH could optimize available interventions to reduce adverse maternal outcomes.

Objective

The objective of this study was to explore a nomogram predicting the risk of postpartum hemorrhage after cesarean delivery for twin pregnancies.

Methods

This single-center retrospective cohort study conducted twin pregnancies who underwent cesarean delivery between January 2014 and July 2021. Propensity score matching at baseline was used to match PPH (blood loss ≥1000 mL) and non-PPH group (blood loss <1000 mL). A nomogram was developed to predict the risk of PPH in cesarean delivery for twin pregnancies. The receiver operating characteristic curve (ROC), calibration plot, and decision curve analysis (DCA) were, respectively, used to evaluate the discrimination, calibration, and clinical utility of the prediction models.

Results

After propensity score matching, 186 twin pregnancies in the PPH group were matched with 186 controls in the non-PPH group. Seven independent prognostic variables, including antepartum albumin, assisted reproductive technology, hypertensive disorders of pregnancy, placenta previa, placenta accrete spectrum, intrapartum cesarean delivered, and estimated weights of twins, were used to build the nomogram. Based on the performance of the model, it appears that a good calibration (Hosmer-Lemeshow χ2 = 4.84, P > 0.05), an excellent predictive ability (area under the curve: 0.778, 95% CI: 0.732-0.825), and a good positive net benefit in the predictive model have been achieved.

Conclusion

The nomogram was first generated to predict PPH in cesarean delivery for twin pregnancies, which could help clinicians to provide a reference for the preoperative surgical plan, choose optimal treatments, optimize healthcare resources, and thereby reduce the associated adverse maternal outcomes.

Modified Delphi study of ultrasound signs associated with placenta accreta spectrum

OBJECTIVE

To determine, by expert consensus through a modified Delphi process, the role of standardized and new ultrasound signs in the prenatal evaluation of patients at high risk of placenta accreta spectrum (PAS).

METHODS

A systematic review of articles providing information on ultrasound imaging signs or markers associated with PAS was performed before the development of questionnaires for the first round of the Delphi process. Only peer-reviewed original research studies in the English language describing one or more new ultrasound sign(s) for the prenatal evaluation of PAS were included. A three-round consensus-building Delphi method was then conducted under the guidance of a steering group, which included nine experts who invited an international panel of experts in obstetric ultrasound imaging in the evaluation of patients at high risk for PAS. Consensus was defined as agreement of ≥ 70% between participants.

RESULTS

The systematic review identified 15 articles describing eight new ultrasound signs for the prenatal evaluation of PAS. A total of 35 external experts were approached, of whom 31 agreed and participated in the first round. Thirty external experts (97%) and seven experts from the steering group completed all three Delphi rounds. A consensus was reached that a prior history of at least one Cesarean delivery, myomectomy or PAS should be an indication for detailed PAS ultrasound assessment. The panelists also reached a consensus that seven of the 11 conventional signs of PAS should be included in the examination of high-risk patients and the routine mid-gestation scan report: (1) loss of the 'clear zone', (2) myometrial thinning, (3) bladder-wall interruption, (4) placental bulge, (5) uterovesical hypervascularity, (6) placental lacunae and (7) bridging vessels. A consensus was not reached for any of the eight new signs identified by the systematic review. With respect to other ultrasound features that are not specific to PAS but increase the probability of PAS at birth, the panelists reached a consensus for the finding of anterior placenta previa or placenta previa with cervical involvement. The experts were also asked to determine which PAS signs should be quantified and consensus was reached only for the quantification of placental lacunae using an existing score. For predicting surgical outcome in patients with a high probability of PAS at delivery, a consensus was obtained for loss of the clear zone, bladder-wall interruption, presence of placental lacunae and presence of placenta previa involving the cervix.

CONCLUSIONS

We have confirmed the continued importance of seven established standardized ultrasound signs of PAS, highlighted the role of transvaginal ultrasound in evaluating the placental position and anatomy of the cervix, and identified new ultrasound signs that may become useful in the future prenatal evaluation and management of patients at high risk for PAS at birth. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The value of a simple sonographic screening test for placenta accreta spectrum prediction: A case-control study

BACKGROUND

Placenta accreta spectrum (PAS) represents life-threatening conditions; however, early diagnosis reduces complications and mortality rates.

AIMS

To develop and evaluate the accuracy of a simple sonographic screening test for PAS prediction.

MATERIALS AND METHODS

A retrospective case-control study of 481 women with singleton pregnancies at 28 weeks or later, with a scarred uterus or placenta praevia, who underwent sonographic testing for PAS detection during 2010-2020. We compared demographic and sonographic features, and delivery outcomes between women who were and were not confirmed to have a PAS condition at delivery. We evaluated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and predictive probability for the sonographic screening model.

RESULTS

Among all the women with at least one sonographic sign (large lacunae or loss of clear zone), the odds ratio (OR) of PAS was 21.7 (95% CI, 16.7-70.4), among those with placenta praevia (and at least one sonographic sign), the OR was 41.9 (95% CI, 15.8-111). For the screening model (the combinations of placental location (major or minor placenta praevia) with at least one sonographic sign (large lacunae or loss of clear zone)), sensitivity, specificity, PPV, NPV and predicted probability were 94.9% (85.8-98.9%), 91.5% (88.4-93.9%), 60.9% (50.1-70.9%), 99.2% (97.7-99.8%) and 92.3%, respectively.

CONCLUSIONS

A combination of simple ultrasound signs for PAS screening may be highly effective for prenatal assessment and prediction of placenta accreta. This screening test can be carried out as routine pregnancy follow-up for women with risk factors for PAS.

Ferumoxytol-enhanced MR demonstration of changes to internal placental structure in placenta accreta spectrum: Preliminary findings

INTRODUCTION

The goal of this pilot study is to determine if ferumoxytol-enhanced MR might provide a new approach to the diagnosis of placenta accreta spectrum (PAS), and if so, to identify signs of PAS.

METHODS

Ten pregnant women were referred for MRI evaluation for PAS. MR studies consisted of pre-contrast SSFSE, SSFP, DWI, and ferumoxytol-enhanced sequences. Post-contrast images were rendered as MIP and MinIP images to separately display the maternal and fetal circulations respectively. Two readers examined the images for architectural changes to placentone (fetal cotyledon) that might distinguish PAS cases from normal. Attention was given to the size and morphology of the placentone, villous tree, and vascularity. In addition, the images were examined for evidence of fibrin/fibrinoid, intervillous thrombus, basal and chorionic plate bulges. Interobserver agreement was characterized with kappa coefficients and levels of confidence for feature identification was recorded on a 10-point scale.

RESULTS

At delivery, there were five normal placentas and five with PAS (one accreta, two increta, two percreta). The ten changes of placental architecture in PAS included: focal/regional expansion of placentone(s); lateral displacement and compression of the villous tree; disruption of a regular pattern of normal placentones; bulging of the basal plate; bulging of the chorionic plate; transplacental stem villi; linear/nodular bands at basal plate; non-tapering villous branches; intervillous hemorrhage; and dilated subplacental vessels. All these changes were more common in PAS; the first five achieved statistical significance in this small sample. The interobserver agreement and confidence for the identification of these features was good to excellent except for dilated subplacental vessels.

DISCUSSION

Ferumoxytol-enhanced MR imaging appears to depict derangements of the internal architecture of placentas with PAS, thereby suggesting a promising new strategy to diagnose PAS.

Foley Catheter as a Tourniquet for Peripartum Hemorrhage Prevention in Patients with Placenta Accreta Spectrum-A Two Case Report and a Review of the Literature

One of the most perilous complications in obstetrics, often leading to severe bleeding and sometimes a need for urgent hysterectomy, is placenta accreta spectrum, which significantly increases the risk of peri-partum complications, even including the risk of death for the mother and the child. Dealing with excessive bleeding in this situation is paramount. We have found a Foley catheter tourniquet to be useful as a temporary tourniquet to control placental and uterine hemorrhage. We have used this method and find it very useful. In this publication, we describe the last two cases of the use of the Foley catheter as a tourniquet for peri-partum hemorrhage prevention, and we will present a review of the literature in this field.

Ultrasonography of the Explanted Uterus in Placenta Accreta Spectrum: Correlation With Intraoperative Findings and Gross Pathology

OBJECTIVE

To better understand placenta accreta spectrum (PAS) by correlating postoperative ultrasonographic findings of the explanted uteroplacental interface with intraoperative findings and gross pathology.

METHODS

We enrolled consecutive pregnant patients aged 18 years and older with a prior cesarean delivery and antenatal diagnosis of lower uterine segment PAS who planned to undergo hysterectomy into this prospective, descriptive study. All underwent cesarean hysterectomy with standardized intraoperative photography. Ultrasonography of explanted postsurgical uteruses was performed by expert radiologists to obtain standard detailed images of the myometrial-placental interface and other areas of interest. Sagittal views of the gross pathologic specimen were photographed. We correlated the intraoperative, ultrasonographic, and gross pathologic findings as a study team and report four consistent patterns that emerged from this systematic evaluation.

RESULTS

Thirty-four consecutive eligible patients were enrolled. The following consistent observations emerged: 1) The uteroplacental interface in the explanted specimen was smooth and distinct. At the point of maximal placental protrusion, the myometrium was imperceptible, but the placenta was confined by a smooth thin echogenic line of uterine serosa (the scar shell) unless surgically disrupted. 2) Every specimen of PAS grade 2-3 showed placenta bulging through the lower uterine segment in the region of prior hysterotomy. 3) Placentas extended to, but not through, the uterovesical interface or scar shell. Dense adhesive disease was found between the placenta and bladder. There were no cases of true bladder invasion. 4) Placental extension beyond the serosa (invasion) has a distinct appearance on postoperative ultrasonography with irregular frond-like protrusion of placental tissue. This appearance was always the result of surgical manipulation and was not present before delivery of the neonate.

CONCLUSION

These findings suggest that PAS severity is likely mediated by progressive scar dehiscence and uterine remodeling, not placental invasion. This challenges the existence of in situ invasive percreta as it is currently described.

Risk factors of MRI findings for predicting patient outcomes of placenta accreta spectrum and placenta previa after prophylactic balloon occlusion of the internal iliac artery

PURPOSE

Our study aimed to identify the risk factors of magnetic resonance imaging (MRI) findings for predicting patient outcomes of placenta accreta spectrum (PAS) and placenta previa after prophylactic balloon occlusion of the internal iliac artery (PBOIIA).

MATERIALS AND METHODS

This retrospective analysis was performed using the clinical records of 46 patients diagnosed with PAS and placenta previa who underwent PBOIIA during caesarean section (CS). The possible clinical risk factors for adverse maternal outcomes were evaluated by consulting patients' clinical records. The inclusion criteria for the massive bleeding group were as follows: estimated blood loss (EBL) > 2500 mL, packed red blood cell (pRBC) transfusion (>4 units), and need for hysterectomy or transcatheter arterial embolization after delivery. The MRI features were compared between the massive and non-massive bleeding groups.

RESULTS

Patients in the massive bleeding group (n = 22) had a significantly longer operation time (p < 0.001), more EBL (p < 0.001), more pRBC transfusions (p < 0.001), and a prolonged postoperative hospital stay (p < 0.05). MRI features showed a T2 dark bands, placenta bulge, and abnormal blood vessels in the placental bed more frequently in the massive bleeding group (p < 0.05). In the multiple logistic regression analysis, T2 dark bands (odds ratio 9.1, p = 0.048) and placental bulge (odds ratio 5.1, p = 0.014) remained statistically significant.

CONCLUSION

T2 dark bands and placental bulges observed on an MRI can predict adverse maternal outcomes in patients with PAS and placenta previa undergoing PBOIIA. If these findings are observed on a preoperative MRI, effective management strategies should be prepared for the possibility of massive hemorrhage during CS.

Bladder involvement in placenta accreta spectrum disorder with placenta previa: MRI findings and outcomes correlation

BACKGROUND

Placental accreta spectrum (PAS) disorder with bladder involvement can be associated with maternal and neonatal morbidity. Magnetic resonance imaging (MRI) may provide accurate preoperative diagnoses.

OBJECTIVE

This study had 2 aims: to retrospectively review the MRI findings for bladder involvement in PAS with placental previa and to correlate bladder involvement with maternal and neonatal outcomes.

MATERIALS AND METHODS

MRI images of 48 patients with severe PAS (increta and percreta) with placenta previa/low-lying placenta were evaluated by 2 experienced radiologists blinded to the final diagnoses. Nine MRI findings and stepwise logistic regression analysis were assessed to identify predictive MRI findings for bladder involvement. The correlations between PAS patients with bladder involvement and clinical outcomes were analyzed using Fisher's exact test.

RESULTS

Of the 48 patients, 27 did not have bladder involvement, while 21 did. Logistic regression analysis identified 2 predictive MRI features for bladder involvement. They were abnormal vascularization (OR,6.94; 95 %CI,1.05-45.75) and loss of the chemical shift line at the uterovesical interface (OR, 4.41; 95 %CI, 0.63-30.98). The sensitivity and specificity of the combined MRI features were 38.1 % and 100 %, respectively (p = 0.001). A significant correlation was found between bladder involvement and massive blood loss during surgery (p = 0.022).

CONCLUSIONS

PAS with bladder involvement was significantly correlated with massive surgical blood loss. Prenatally, the disorder was predicted with high specificity by the combination of loss of chemical shift artifacts in the steady-state free precession sequence and abnormal vascularization at the uterovesical interface on MRI.

A simple guide to ultrasound screening for placenta accreta spectrum for improving detection and optimizing management in resource limited settings

Placenta accreta spectrum is a pregnancy complication associated with severe morbidity and maternal mortality especially when not suspected antenatally and appropriate management instigated. Women in resource-limited settings are more likely to face adverse outcomes due to logistic, technical, and resource inadequacies. Accurate prenatal imaging is an important step in ensuring good outcomes because it allows adequate preparation and an appropriate management approach. This article provides a simple three-step approach aimed at guiding clinicians and sonographers with minimal experience in placental accreta spectrum through risk stratification and basic prenatal screening for this condition both with and without Doppler ultrasound.

The use of the double uterine segment tourniquet in obstetric hysterectomy for bleeding control in patients with placenta accreta spectrum

OBJECTIVES

To evaluate surgical outcomes of using a double uterine segment tourniquet in obstetric hysterectomy for bleeding control in patients with placenta accreta spectrum.

METHODS

Retrospective case-control study conducted at the Central Hospital of San Luis Potosi, Mexico. Patients with the diagnosis of placenta accreta spectrum who underwent obstetric hysterectomy were included. Two groups were formed: in the first, a double uterine segment tourniquet was used; and in the second, the hysterectomy was performed without a tourniquet. Primary surgical outcomes were compared.

RESULTS

Forty patients in each group were included. The use of a double uterine segment tourniquet had lower total blood loss compared with the non-tourniquet group (1054.00 ± 467.02 vs. 1528.75 ± 347.12 mL, P = 0.0171) and a lower drop in hemoglobin (1.74 ± 1.10 vs. 2.60 ± 1.25 mg/dL, P = 0.0486). Ten patients (23.80%) in the double tourniquet group required blood transfusion, compared with 26 (65.00%) in the non-tourniquet group (P = 0.0003). Surgical time did not show a statistical difference between groups.

CONCLUSION

The use of a uterine segment tourniquet in obstetric hysterectomy may improve surgical outcomes in patients with placenta accreta spectrum with no difference in surgical time and urinary tract lesions.

Pregnancies in Women with a Previous Complete Uterine Rupture

Objective

To study the outcomes of new pregnancies after a previous complete uterine rupture.

Design

Descriptive study based on population data from the Medical Birth Registry of Norway, the Patient Administration System, and the medical records. Sample. Maternities with a previous complete uterine rupture in Norway during the period 1967-2011 (N = 72), extracted from 2 455 797 maternities.

Method

We measured the rate of new complete ruptures and partial ruptures, as well as the maternal and perinatal outcomes of these pregnancies. The characteristics of both previous ruptures and new ruptures were described.

Results

Among 72 maternities, there were thirty-seven with previous ruptures in the lower segment (LS) and 35 outside the LS. We found three new complete ruptures and six uneventful partial ruptures, resulting in a rate of 4.2% and 8.3%, respectively. All three complete ruptures occurred preterm in scars outside the LS. The rate of the new complete rupture was 0% in those with previous ruptures in the LS and 8.6% in those with previous ruptures outside the LS. The corrected perinatal mortality was 1.3%, and prematurity (<37 weeks) was high (36.1%); this was noticed even in the absence of new ruptures and was mostly iatrogenic. Two hysterectomies were performed in the absence of rupture and two cases had abnormal invasive placenta.

Conclusion

The prognosis for pregnancies after a previous complete uterine rupture is favorable. Prematurity is a problem caused by both obstetrician and mother's anxiety; therefore, the timing of delivery is the most challenging. Management should include careful counseling, vigilance for symptoms, and immediate delivery when a rupture is suspected.

Abnormal placenta implantation. Integration between first- and third-trimester imaging in predicting the severity of Placenta Accreta Spectrum (PAS) disorders

Placenta accreta spectrum (PAS) disorders are pathological conditions correlated to a high risk of adverse maternal surgical outcomes, especially if not diagnosed. In the last 10 years, the literature interest for prenatal diagnosis of PAS disorders has been noticeably greater. More recently, significant progression in prenatal imaging techniques permitted an increase of early identified cases and a more accurate diagnosis of these anomalies, especially in women with multiple risk factors. The aim of this chapter is to give an overhaul on prenatal diagnosis of PAS disorders throughout gestation and to report whether integration between first- and third-trimester ultrasound can predict the development and severity of these anomalies.

A Risk-Prediction Model for Placenta Accreta Spectrum Severity From Standardized Ultrasound Markers

We aimed to generate a model to predict the risk of a woman having normal, abnormally adherent (AAP) or abnormally invasive placentation (AIP) based on the presence of recently codified ultrasound (US) markers and disease definitions of placenta accreta spectrum (PAS). We recruited women with anterior low-lying placenta or placenta previa and a history of previous caesarean delivery to a prospective cohort study. US markers of abnormal placentation were recorded on a standardized pro forma. The presence and International Federation of Gynecology and Obstetrics grade of PAS was evaluated clinically and histologically at delivery. Markers demonstrating a predictive relationship to PAS were incorporated into a logistic regression model. A total of 106 women were included, of whom 42 (40%) were normal, 24 (23%) had AAP and 40 (38%) had AIP. A model including just four key variables (loss of clear zone, abnormal placental lacunae, placental bulge and bladder wall interruption) was shown to reliably predict presence and severity of PAS, with an optimism-corrected C-index of 0.901. A simple model incorporating four US markers can predict likelihood and severity of PAS with high accuracy. This is the first time this has been demonstrated using the recently codified definitions of the US signs and disease definitions. Further work will see our model applied prospectively to a large patient cohort, ideally through a smartphone-based application, for external validation.

Curative effect of cervical lifting suture combined with the improved Hayman suture in pernicious placenta previa under noninterventional conditions: A retrospective cohort study

OBJECTIVE

To propose a novel operative strategy involving cervical lifting suture (CLS) in conjunction with the improved Hayman suture (CLS-Hayman) to apply in the cesarean section of pernicious placenta previa (PPP) under noninterventional conditions and evaluate the curative effect of the CLS-Hayman operation by comparing with conventional CLS.

METHODS

A retrospective cohort study was conducted on 119 pregnant women diagnosed with PPP, including 50 cases in the CLS-Hayman group and 69 cases in the CLS group. The authors used different statistical methods to compare intraoperative bleeding, 24-h postpartum bleeding, postoperative complication rates, and uterine involution between the two groups under noninterventional conditions.

RESULTS

The median intraoperative blood loss was 800 mL in the CLS-Hayman group versus 1000 mL in the CLS group. The amount of 24-h postpartum bleeding in the CLS-Hayman group was lower than that in the CLS group. The complication rates in the two groups were 12% and 27.5%, respectively (P = 0.04). B-ultrasound or magnetic resonance imaging data showed that the uterine involution was better in the CLS-Hayman group.

CONCLUSION

The CLS-Hayman suture achieves the desired intraoperative hemostasis and also stands out for its better prevention of postpartum hemorrhage, better prognosis at follow-up, and lower complication rates.

Identification of altered miRNAs and their targets in placenta accreta

Placenta accreta spectrum (PAS) is one of the major causes of maternal morbidity and mortality worldwide with increasing incidence. PAS refers to a group of pathological conditions ranging from the abnormal attachment of the placenta to the uterus wall to its perforation and, in extreme cases, invasion into surrounding organs. Among them, placenta accreta is characterized by a direct adhesion of the villi to the myometrium without invasion and remains the most common diagnosis of PAS. Here, we identify the potential regulatory miRNA and target networks contributing to placenta accreta development. Using small RNA-Seq followed by RT-PCR confirmation, altered miRNA expression, including that of members of placenta-specific miRNA clusters (e.g., C19MC and C14MC), was identified in placenta accreta samples compared to normal placental tissues. In situ hybridization (ISH) revealed expression of altered miRNAs mostly in trophoblast but also in endothelial cells and this profile was similar among all evaluated degrees of PAS. Kyoto encyclopedia of genes and genomes (KEGG) analyses showed enriched pathways dysregulated in PAS associated with cell cycle regulation, inflammation, and invasion. mRNAs of genes associated with cell cycle and inflammation were downregulated in PAS. At the protein level, NF-κB was upregulated while PTEN was downregulated in placenta accreta tissue. The identified miRNAs and their targets are associated with signaling pathways relevant to controlling trophoblast function. Therefore, this study provides miRNA:mRNA associations that could be useful for understanding PAS onset and progression.

Highly expressed FYN promotes the progression of placenta accreta by activating STAT3, p38, and JNK signaling pathways

Placenta accreta is an abnormality of the placenta caused by the chorionic villi invading the muscular layer, which can cause serious bleeding, infection, shock, bladder invasion, uterine perforation, and even death. However, the etiology of placental accreta is not entirely clear. In the present study, high-throughput sequencing results showed that FYN is highly expressed in the placental accreta position in the placenta accreta group and is a key regulator of cell invasion and migration. Therefore, we aimed to evaluate the role and potential molecular mechanism of FYN in placenta accreta. The results showed that FYN was highly expressed in the placenta tissues of the placenta accreta group. Furthermore, the levels of phosphorylated STAT3, p38, and JNK in the placenta accreta group were remarkably increased compared with those in the control group. In addition, FYN knockdown considerably decreased the migration and invasion rates of trophoblast cells (HTR8/SVneo) and inhibited the levels of phosphorylated STAT3, p38, and JNK. After subsequently blocking these signaling pathways, the invasion and migration abilities of HTR8/SVneo cells were substantially decreased. In conclusion, FYN may promote excessive trophocyte cell invasion by activating STAT3, p38, and JNK pathways and can be a new target for placenta accreta prevention and treatment.

Automatic Image Guidance for Assessment of Placenta Location in Ultrasound Video Sweeps

Ultrasound-based assistive tools are aimed at reducing the high skill needed to interpret a scan by providing automatic image guidance. This may encourage uptake of ultrasound (US) clinical assessments in rural settings in low- and middle-income countries (LMICs), where well-trained sonographers can be scarce. This paper describes a new method that automatically generates an assistive video overlay to provide image guidance to a user to assess placenta location. The user captures US video by following a sweep protocol that scans a U-shape on the lower maternal abdomen. The sweep trajectory is simple and easy to learn. We initially explore a 2-D embedding of placenta shapes, mapping manually segmented placentas in US video frames to a 2-D space. We map 2013 frames from 11 videos. This provides insight into the spectrum of placenta shapes that appear when using the sweep protocol. We propose classification of the placenta shapes from three observed clusters: complex, tip and rectangular. We use this insight to design an effective automatic segmentation algorithm, combining a U-Net with a CRF-RNN module to enhance segmentation performance with respect to placenta shape. The U-Net + CRF-RNN algorithm automatically segments the placenta and maternal bladder. We assess segmentation performance using both area and shape metrics. We report results comparable to the state-of-the-art for automatic placenta segmentation on the Dice metric, achieving 0.83 ± 0.15 evaluated on 2127 frames from 10 videos. We also qualitatively evaluate 78,308 frames from 135 videos, assessing if the anatomical outline is correctly segmented. We found that addition of the CRF-RNN improves over a baseline U-Net when faced with a complex placenta shape, which we observe in our 2-D embedding, up to 14% with respect to the percentage shape error. From the segmentations, an assistive video overlay is automatically constructed that (i) highlights the placenta and bladder, (ii) determines the lower placenta edge and highlights this location as a point and (iii) labels a 2-cm clearance on the lower placenta edge. The 2-cm clearance is chosen to satisfy current clinical guidelines. We propose to assess the placenta location by comparing the 2-cm region and the bottom of the bladder, which represents a coarse localization of the cervix. Anatomically, the bladder must sit above the cervix region. We present proof-of-concept results for the video overlay.

Emergency Obstetric Hysterectomy after Conservative Management of Placenta Accreta

Background

Obstetric hemorrhage is a frequent and life-threatening complication of either vaginal or cesarean delivery. It can be due to many causes, one of which is placenta accreta, the abnormal invasion of the placenta into the myometrial wall of uterus. Ultrasonography is the first line diagnostic method that can lead to the diagnosis of placenta accreta although, the depth of penetration is estimated by magnetic resonance imaging. Placenta accreta is a life-threatening situation requiring an experienced health care team for its management. Hysterectomy is usually performed although, conservative management might be preferred in carefully selected cases. Case Presentation. A 32-year-old woman (G2, P0) who had an inconsistently monitored pregnancy appeared at a regional hospital with contractions at 39th week of gestation. In her first pregnancy, she was subjected to cesarean section due to delay in second stage of labor and unfortunately her child died due to sudden cardiac death. During C-section, placenta accreta was identified. Given her previous history and her desire to maintain fertility, conservative management was initially planned to preserve her uterus. However, due to persisting vaginal bleeding immediately after delivery an emergency hysterectomy was performed.

Conclusion

Conservative management of placenta accreta can be considered in some special cases with the aim to spare fertility. However, if bleeding cannot be controlled during the immediate postpartum period, emergency hysterectomy is unavoidable. A specialized multidisciplinary medical team is required to optimize management.

Placenta Accreta Spectrum Diagnosis Challenges and Controversies in Current Obstetrics: A Review

Background

Placenta accreta spectrum (PAS) is the most common obstetric complication in current obstetrics in which the placenta is fully or partially attached to the uterine myometrial layer at delivery. This is commonly due to the deficiency of the uterine interface between the uterine endometrial and myometrial layers leading to abnormal decidualization at the uterine scar area, which permits the abnormally placental anchoring villous and trophoblasts, deeply invade the myometrium. The prevalence of PAS is globally at rising trends every day in modern obstetrics originally due to the high increasing rate of cesarean sections, placenta previa, and assisted reproductive technology (ART). Thus, the early and precise diagnosis of PAS is imperative to prevent maternal intrapartum or postpartum bleeding complications.

Objective

The main aim of this review is to debate the current challenges and controversies in the routine diagnosis of PAS diseases in obstetrics.

Data Source

We retrospectively reviewed the recent articles on different methods of diagnosing PAS in PubMed, Google Scholar, Web of Science, Medline, Embase, and other website databases.

Results

Despite that, the standard ultrasound is a reliable and key tool for the diagnosis of PAS, the lack of ultrasound features does not exclude the diagnosis of PAS. Therefore, clinical assessment of risk factors, MRI tests, serological markers, and placental histopathological tests are also indispensable for the prediction of PAS. Previously, limited studies reached a high sensitivity rate of diagnosis PAS in appropriate cases, while many studies recommended the inclusion of different diagnosis methods to improve the diagnosis accuracy.

Conclusion

A multidisciplinary squad with well-experienced obstetricians, radiologists, and histopathologists should be involved in the establishment of the early and conclusive diagnosis of PAS.

Placenta accreta spectrum: the pattern and character of intraplacental blood flow by color and spectral Doppler

PURPOSE

To characterize intraplacental blood flow patterns in placenta accreta spectrum (PAS) with color and spectral Doppler imaging.

METHODS

Thirty-two patients at risk for PAS underwent ultrasound imaging with both color and spectral Doppler. The placenta was inspected for areas of vascularity by color Doppler, particularly within the lower uterine segment. Spectral Doppler waveforms were obtained from these vessels and categorized as either intraplacental or subplacental (myometrial), venous or arterial, fetal or maternal (based on heart rate). Arterial waveforms were measured for heart rate, peak systolic velocity, end diastolic velocity, and resistive index. Statistical comparisons were made between cases with and without PAS using Fisher exact tests (categorical variables) and Mann-Whitney U tests (numerical indices). Interobserver agreement was characterized with kappa coefficients.

RESULTS

At delivery, there were 19 cases with PAS and 13 without PAS. On ultrasound studies, clustered intraplacental vascularity was found in the lower uterine segment in 66% of cases (95% of PAS cases and 23% cases without PAS; p < 0.0001). Maternal arterial waveforms were found within the vascular cluster in 84% of PAS cases and 15% of cases without PAS (p < 0.0001). A traversing fetal artery was found within the vascular cluster in 56% of cases (84% PAS cases and 15% cases without PAS; p = 0.001). Venous waveforms were found in 84% of PAS cases and 15% of cases without PAS. Interobserver agreement was good to excellent.

CONCLUSION

Intraplacental blood flow pattern in PAS is characterized by an intraplacental vascular cluster containing low-resistance maternal arterial flow and transplacental fetal arteries.

Placenta segmentation in ultrasound imaging: Addressing sources of uncertainty and limited field-of-view

Automatic segmentation of the placenta in fetal ultrasound (US) is challenging due to the (i) high diversity of placenta appearance, (ii) the restricted quality in US resulting in highly variable reference annotations, and (iii) the limited field-of-view of US prohibiting whole placenta assessment at late gestation. In this work, we address these three challenges with a multi-task learning approach that combines the classification of placental location (e.g., anterior, posterior) and semantic placenta segmentation in a single convolutional neural network. Through the classification task the model can learn from larger and more diverse datasets while improving the accuracy of the segmentation task in particular in limited training set conditions. With this approach we investigate the variability in annotations from multiple raters and show that our automatic segmentations (Dice of 0.86 for anterior and 0.83 for posterior placentas) achieve human-level performance as compared to intra- and inter-observer variability. Lastly, our approach can deliver whole placenta segmentation using a multi-view US acquisition pipeline consisting of three stages: multi-probe image acquisition, image fusion and image segmentation. This results in high quality segmentation of larger structures such as the placenta in US with reduced image artifacts which are beyond the field-of-view of single probes.

Placenta Accreta Spectrum: Correlation between FIGO Clinical Classification and Histopathologic Findings

OBJECTIVE

Placenta accreta spectrum (PAS) covers a wide spectrum of placental adherence/invasion with varied clinical significance. Histopathologic examination is considered the confirmatory gold standard, but is only obtained sometime after definitive treatment. The International Federation of Gynecology and Obstetrics (FIGO) has published a new clinical classification that can be assigned at delivery, and we aimed to investigate the association between this new FIGO classification and histopathology and also to assess its correlation with maternal outcomes.

STUDY DESIGN

We studied a retrospective cohort of 185 patients with histopathologically proven PAS managed at our referral center between September 2012 and January 2019. Two experienced surgeons retrospectively reviewed charts and assigned the FIGO grading based on findings reported at delivery. A third experienced reviewer adjudicated to determine the classification used for final analysis. Categorical outcomes were compared with the use of chi-squared and the Fisher exact test, as appropriate. A multivariate model was designed to adjust outcomes in different FIGO groups for the involvement of a formal multidisciplinary management team.

RESULTS

Among 185 patients, there were 41 (22%) placenta accreta, 44 (24%) placenta increta, and 100 (54%) placenta percreta on histopathology. The inter-rater reliability was found to be substantial with Kappa = 0.661 (p < 0.001), and 95% confidence interval (CI): 0.449-0.872. There was a significant association between all histopathology groupings and the FIGO clinical classification (p < 0.001). However, we found no association between FIGO classifications and maternal complications.

CONCLUSION

The new FIGO clinical classification is strongly associated with histopathologic findings. A better understanding of the depth and extent of invasion as afforded by the clinical classification system will help standardize reporting and future research.

KEY POINTS

· PAS includes a wide spectrum of placental invasion with varied clinical significance.. · Histopathological examination is considered the confirmatory gold standard.. · The new FIGO clinical classification is strongly associated with histopathologic findings..

The Association between Placenta Accreta Spectrum Severity and Incidence of Small for Gestational Age Neonates

OBJECTIVE

The aim of the study is to evaluate whether pathologic severity of placenta accreta spectrum (PAS) is correlated with the incidence of small for gestational age (SGA) and neonatal birthweight.

STUDY DESIGN

This was a multicenter cohort study of viable, non-anomalous, singleton gestations delivered with histology-proven PAS. Data including maternal history, neonatal birthweight, and placental pathology were collected and deidentified. Pathology was defined as accreta, increta, or percreta. The primary outcome was rate of SGA defined by birth weight less than the 10th percentile. The secondary outcomes included incidence of large for gestational age (LGA) babies as defined by birth weight greater than the 90th percentile as well as incidence of SGA and LGA in preterm and term gestations. Statistical analysis was performed using Chi-square, Kruskal-Wallis, and log-binomial regression. Increta and percreta patients were each compared with accreta patients.

RESULTS

Among the cohort of 1,008 women from seven United States centers, 865 subjects were included in the analysis. The relative risk (RR) of SGA for increta and percreta did not differ from accreta after adjusting for confounders (adjusted RR = 0.63, 95% confidence interval [CI]: 0.36-1.10 for increta and aRR = 0.72, 95% CI: 0.45-1.16 for percreta). The results were stratified by placenta previa status, which did not affect results. There was no difference in incidence of LGA (p = 1.0) by PAS pathologic severity. The incidence of SGA for all PAS patients was 9.2% for those delivered preterm and 18.7% for those delivered at term (p = 0.004). The incidence of LGA for all PAS patients was 12.6% for those delivered preterm and 13.2% for those delivered at term (p = 0.8203).

CONCLUSION

There was no difference in incidence of SGA or LGA when comparing accreta to increta or percreta patients regardless of previa status. Although we cannot suggest causation, our results suggest that PAS, regardless of pathologic severity, is not associated with pathologic fetal growth in the preterm period.

KEY POINTS

· PAS severity is not associated with SGA in the preterm period.. · PAS severity is not associated with LGA.. · Placenta previa does not affect the incidence of SGA in women with PAS..

Value of 3D ultrasound flow imaging combined with serum AFP, β-hCG, sFlt-1 and CK in the diagnosis of placenta accreta

PURPOSE

To analyze the diagnostic value of placenta three-dimensional (3D) energy blood flow parameters combined with maternal serum AFP, β-hCG, sFlt-1 and CK levels for PA.

METHODS

30 pregnant women with PA and 30 pregnant women with normal placenta were randomly selected in the Affiliated Maternal and Child Health Hospital of Nantong University from January 2021 to December 2021. Thereafter, the 3D energy ultrasound was applied to detect the placenta VI, FI and VFI. Moreover, the diagnostic value of different parameters combined with serum AFP, β-hCG, sFlt-1 and CK levels for PA was analyzed.

RESULTS

Multivariate analysis results indicated that, gravidity > 2 and with/without placenta previa were the independent risk factors for PA (P < 0.05). In PA group, the AFP, β-hCG, CK, placenta VI, FI and VFI values were higher than those in non-PA group, while sFlt-1 was apparently lower than that in non-PA group. With the increase in PA degree, the serum AFP, β-hCG and CK levels increased. Meanwhile, serum sFlt-1 level was negatively correlated with PA degree. Serum AFP, β-hCG, sFlt-1, CK and placenta VFI showed prediction potency for PA, and their combined detection attained the optimal diagnostic value for predicting PA. ROC curve analysis suggested that, serum AFP, β-hCG, sFlt-1, CK and 3D ultrasound VFI value had the greatest AUC values in predicting PA, which might provide reference for the clinical diagnosis and disease evaluation of PA. Conclusion Serum AFP, β-hCG, sFlt-1, CK and placental VFI can increase the consistency in the diagnosis of PA. Serum markers combined with 3D ultrasound blood flow imaging can improve the sensitivity and specificity of prenatal diagnosis of PA, which provides an important reference for clinical diagnosis and treatment.

Interactions between ultrasonographic cervical length and placenta accreta spectrum on severe postpartum hemorrhage in women with placenta previa

OBJECTIVE

To explore the interactions between cervical length (CL) and placenta accreta spectrum (PAS) on severe postpartum hemorrhage (SPPH) in patients with placenta previa.

METHODS

A retrospective case-control study was conducted at four medical centers in China, and 588 patients with placenta previa were included. The logistic regression analysis and restricted cubic splines (RCS) were used to evaluate the association between CL and SPPH. Furthermore, the joint effect of CL and PAS on SPPH was assessed, and the additive and multiplicative interactions were calculated.

RESULTS

After adjusting for potential confounders, the negative linear dose-response relationship was confirmed by RCS, and the change of odds ratio (OR) was more significant when CL was 2.5 cm or less. The risk of SPPH was significantly higher when CL of 2.5 cm or less co-existed with placenta increta/percreta than when CL of 2.5 cm less, or placenta increta/percreta existed alone (adjusted OR [aOR]_{CL ≤2.5cm&placenta accreta/non-PAS} 3.40, 95% confidence interval [CI] 1.37-8.45; aOR_{placenta increta/percreta&CL >2.5cm} 4.75, 95% CI 3.03-7.47; aOR_{CL ≤2.5cm&placenta increta/percreta} 14.51, 95% CI 6.08-34.64), and there might be additive interaction between CL and placenta increta/percreta on SPPH (attributable proportion due to interaction 50.7%, 95% CI 6.1%-95.3%).

CONCLUSION

If CL was routinely performed during PAS evaluation, the increased OR of short CL and PAS could allow better patient preparation through counseling.

Unsuspected placenta accreta spectrum at vaginal delivery: assessment of incidence, characteristics, and maternal morbidity

BACKGROUND

Placenta accreta spectrum refers to morbidly adherent trophoblastic tissue invading into the gravid uterus and is associated with significant maternal morbidity. Most cases of placenta accreta spectrum are suspected antenatally, and most patients undergo planned, late-preterm cesarean hysterectomy to reduce the risk of morbidity. Rarely, however, placenta accreta spectrum is incidentally diagnosed at vaginal delivery, but there is a scarcity of data regarding these events.

OBJECTIVE

This study aimed to examine the incidence, characteristics, and outcomes of pregnant individuals with incidentally diagnosed placenta accreta spectrum at term vaginal delivery.

STUDY DESIGN

This was a retrospective cohort study investigating the Healthcare Cost and Utilization Project's National Inpatient Sample. The study population was 8,694,669 term vaginal deliveries from January 2016 to December 2019. Exclusion criteria included previous uterine scar, placenta previa, and preterm delivery. Exposure was assigned by the diagnosis of placenta accreta spectrum. The main outcomes were: (1) incidence rate, (2) clinical and pregnancy characteristics, and (3) maternal morbidity related to unsuspected placenta accreta spectrum at vaginal delivery. Multivariable binary logistic regression analysis and inverse probability of treatment weighting were fitted for statistical analysis.

RESULTS

Unsuspected placenta accreta spectrum was reported in 1 in 3797 vaginal deliveries. In a multivariable analysis, the following were associated with increased likelihood of unsuspected placenta accreta spectrum (all, P<.05): (1) patient factor with older age, (2) uterine factors such as uterine anomaly and uterine myoma, (3) pregnancy factors including early-term delivery and previous recurrent pregnancy losses, and (4) fetal factors of in utero growth restriction and demise. Of those, uterine anomaly had the greatest association with unsuspected placenta accreta spectrum (adjusted odds ratio, 6.23; 95% confidence interval, 4.20-9.26). In a propensity score-weighted model, patients in the unsuspected placenta accreta spectrum group were more likely to have hemorrhage (65.2% vs 4.1%), blood product transfusion (21.3% vs 0.6%), hysterectomy (14.9% vs <0.1%), coagulopathy (2.9% vs 0.1%), and shock (2.9% vs <0.1%) compared with those without placenta accreta spectrum. Patients in the unsuspected placenta accreta spectrum group were also more likely to receive manual removal of the placenta compared with those in the non-placenta accreta spectrum group (25.1% vs 0.6%).

CONCLUSION

This study suggests that although unsuspected placenta accreta spectrum among patients undergoing term vaginal delivery is rare, it is associated with significant morbidity. The observed association between uterine anomalies and placenta accreta spectrum warrants further investigation.

Prediction of placenta accreta spectrum by combining deep learning and radiomics using T2WI: a multicenter study

PURPOSE

To achieve prenatal prediction of placenta accreta spectrum (PAS) by combining clinical model, radiomics model, and deep learning model using T2-weighted images (T2WI), and to objectively evaluate the performance of the prediction through multicenter validation.

METHODS

A total of 407 pregnant women from two centers undergoing preoperative magnetic resonance imaging (MRI) were retrospectively recruited. The patients from institution I were divided into a training cohort (n = 298) and a validation cohort (n = 75), while patients from institution II served as the external test cohort (n = 34). In this study, we built a clinical prediction model using patient clinical data, a radiomics model based on selected key features, and a deep learning model by mining deep semantic features. Based on this, we developed a combined model by ensembling the prediction results of the three models mentioned above to achieve prenatal prediction of PAS. The performance of these predictive models was evaluated with respect to discrimination, calibration, and clinical usefulness.

RESULTS

The combined model achieved AUCs of 0.872 (95% confidence interval, 0.843 to 0.908) in the validation cohort and 0.857 (0.808 to 0.894) in the external test cohort, both of which outperformed the other models. The calibration curves demonstrated excellent consistency in the validation cohort and the external test cohort, and the decision curves indicated high clinical usefulness.

CONCLUSION

By using preoperative clinical information and MRI images, the combined model can accurately predict PAS by ensembling clinical model, radiomics model, and deep learning model.

Diffusion and perfusion MRI parameters in the evaluation of placenta accreta spectrum disorders in patients with placenta previa

OBJECTIVES

To evaluate the placental function by monoexponential, biexponential, and diffusion kurtosis MR imaging (MRI) in patients with placenta previa.

METHODS

A total of 62 patients with placenta accreta spectrum (PAS) disorders and 11 patients with normal placentas were retrospectively enrolled, who underwent conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI). The apparent diffusion coefficient (ADC) and exponential ADC (eADC) from standard DWI, mean 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.

RESULTS

Comparisons between patients with PAS disorders and patients with normal placentas demonstrated that MD mean, D mean, and D* mean values in patients with PAS disorders were significantly higher than those in patients with normal placentas (p < 0.05). Comparisons between patients with accreta, increta, and percreta, and patients with normal placentas showed that the D mean was significantly higher in patients with placenta increta and percreta than in patients with normal placentas (p < 0.05).

CONCLUSION

The accreta lesions in PAS disorders had deceased cellularity and increased blood movement. The alteration of placental cellularity was more prominent in placenta increta and percreta.

Prediction of clinical outcomes in women with placenta accreta spectrum using machine learning models: an international multicenter study

INTRODUCTION

Placenta accreta spectrum is a major obstetric disorder that is associated with significant morbidity and mortality. The objective of this study is to establish a prediction model of clinical outcomes in these women.

MATERIALS AND METHODS

PAS-ID is an international multicenter study that comprises 11 centers from 9 countries. Women who were diagnosed with PAS and were managed in the recruiting centers between 1 January 2010 and 31 December 2019 were included. Data were reanalyzed using machine learning (ML) models, and 2 models were created to predict outcomes using antepartum and perioperative features. ML model was conducted using python® programing language. The primary outcome was massive PAS-associated perioperative blood loss (intraoperative blood loss ≥2500 ml, triggering massive transfusion protocol, or complicated by disseminated intravascular coagulopathy). Other outcomes include prolonged hospitalization >7 days and admission to the intensive care unit (ICU).

RESULTS

727 women with PAS were included. The area under curve (AUC) for ML antepartum prediction model was 0.84, 0.81, and 0.82 for massive blood loss, prolonged hospitalization, and admission to ICU, respectively. Significant contributors to this model were parity, placental site, method of diagnosis, and antepartum hemoglobin. Combining baseline and perioperative variables, the ML model performed at 0.86, 0.90, and 0.86 for study outcomes, respectively. Ethnicity, pelvic invasion, and uterine incision were the most predictive factors in this model.

DISCUSSION

ML models can be used to calculate the individualized risk of morbidity in women with PAS. Model-based risk assessment facilitates a priori delineation of management.

Correlation of placental thickness and placenta percreta in patients with placenta previa: findings from MRI

INTRODUCTION

This study aimed to identify if placental thickness measured from MRI images correlated with placenta percreta in patients with placenta previa.

METHODS

Placental thickness was retrospectively measured in 161 patients from July 2018 to August 2020. The measurements were performed at the thickest part of the placenta in the lower uterine segment on the mid-sagittal plane MR images by two independent radiologists. Intraoperative and pathologic findings were the standard of reference. Univariate and multivariate analyses were performed to identify the relationship between clinical features, placental thickness, and placenta percreta. The predictive ability of placental thickness was demonstrated using receiver operating characteristic curve analysis.

RESULTS

Placental thickness in patients with placenta percreta was significantly higher than in patients with placenta increta, placenta accreta, and normal placentas (p < 0.05). Multivariate analysis revealed that placental thickness was the only independent risk factor for placenta percreta. The cutoff value of placental thickness was 4.35 cm for differentiating placenta percreta in patients with placenta previa.

DISCUSSION

Patients with placenta percreta had the highest placental thickness. Placental thickness was correlated with placenta percreta.

Efficacy of distal haemostasis during caesarean delivery in women with placenta accreta spectrum disorders

Pregnancies complicated by the placenta praevia are associated with an increased risk of massive obstetric bleeding and high rates of hysterectomy which are often caused by the placenta accreta. The aim of our study was to identify the risk factors for placenta praevia associated with PAS disorders and the efficacy of distal haemostasis during Cesarean delivery.

METHODS

This was a cohort study carried out between 2014 and 2020 in 532 women with abnormal placental localization and attachment. The placental attachment spectrum (PAS) disorder diagnosis was confirmed during the surgery and by the histology results in 164/532 participants. Depending on the surgical approach during the Cesarean delivery, patients were divided into three groups. In Group 1 (n = 52), patients underwent bilateral uterine artery ligation. In Group 2 (n = 33), we used the combined compression haemostasis approach including the placement of tourniquets and insertion of an intrauterine balloon for controlled tamponade. In Group 3 (n = 79), we used the combination of surgical haemostasis with the controlled intrauterine tamponade using the vaginal and intrauterine Zhukovsky balloon.

RESULTS

PAS was observed in 30.8% of the placenta praevia cases, and in 93.3% was associated with the presence of a uterine scar. Women with the placenta praevia and PAS had a significantly higher number of past deliveries (р = .001). According to the FIGO classification, 53.8% of women with placenta praevia observed during the Cesarean had РА1 and 46.2% PA2. With regards to the PAS disorders observed in 30.8% of patients, 38.4% had PAS3, 34.7% PAS4, 18.3% PAS5 and 8.5% PAS6. The histology analysis showed normal placental attachment in 42.9% of the total number of study participants, placenta accreta in 28.2%, placenta increta in 16.7%, and placenta percreta in 12.2%. In Group 1, we performed the resection of uterine wall with the attached portion of the placenta in 13.5% of women, in Group 2 in 30.3% women, and in Group 3 in 50.6% women. There was a significant 4.8-fold reduction in the number of hysterectomies in Group 3 versus Group 2 (р = .043) and a 4.4-fold reduction in Group 2 versus Group 1 (р = .003). In Group 2, the volume of blood loss was 1.3-fold lower and in Group 3 1.5-fold lower than in Group 1. Conclusion: The techniques of compression distal haemostasis evaluated in this study in women with PAS are efficacious in the reduction of adverse maternal outcomes and should be used more widely in clinical practice.

Evaluation of the Tramline Sign in the Prediction of Placenta Accreta Spectrum and Perioperative Outcomes in Anterior Placenta Previa

PURPOSE

 To evaluate perioperative outcomes and the prognostic role of the tramline sign in a cohort of women with anterior placenta previa.

MATERIALS AND METHODS

 Retrospective analysis of 3D ultrasound volumes from women with anterior placenta previa who underwent ultrasound examination beyond 32 weeks. 3D and 3D color volumes were obtained from a sagittal section of the uterus bisecting a partially full bladder and processed using Crystal Vue and Crystal Vue Flow rendering to look for the "tramline sign". "Partial obliteration" was defined as a loss of some or part of the uterine-serosal interface and "full obliteration" as when both interfaces were interrupted. Postnatal ascertainment of placenta accreta spectrum (PAS) was confirmed by findings recorded intraoperatively or on a pathology report.

RESULTS

 65 cases were included. The tramline sign was "partially" (17) or "fully" (19) obliterated in 36 cases (55.4 %), and present in 29 (44.6 %). Obliteration was associated with earlier gestational age at delivery (35 + 1 (26 + 3-38 + 3) vs. 36 + 4 (25 + 3-38 + 0) weeks, p = 0.005), greater estimated blood loss (800 (400-11 000) vs. 600 (300-2100) mls, p = 0.003), longer operative time (155 (60-240) vs. 54 (25-80) minutes, p < 0.001), higher rate of hysterectomy (97.2 % vs. 0.0 %, p < 0.001), longer postoperative admission (7 (3-19) vs. 3 (1-5) days, p < 0.001) and a 100 % rate of postnatal diagnosis of PAS. The finding of an "obliterated" tramline sign identified all women that required hysterectomy and all cases of PAS.

CONCLUSION

 A "partially or fully obliterated" tramline sign is strongly associated with indicators of operative complexity, the postnatal confirmation of PAS, and the need for peripartum hysterectomy.

Accuracy of ultrasound for the detection of placenta accreta spectrum in a universal screening population

OBJECTIVES

The current study aimed to determine the sensitivity and specificity of ultrasound for the diagnosis of placenta accreta spectrum (PAS) in a universal screening population and assesses the added value of magnetic resonance imaging (MRI).

METHODS

This retrospective analysis evaluated 5219 patients with singleton pregnancies who had a standardized ultrasound (US) examination in our unit and delivered at our institution between 2014 and 2019.

RESULTS

A total of 181 (3.5%) of 5219 (100%) patients had a suspicion or diagnosis of PAS with US. The accuracy of US in detecting placenta increta/percreta showed a sensitivity of 100%, specificity of 99.9%, positive predictive value of 82.4%, and a negative predictive value of 100%. The diagnosis of all forms of PAS showed a sensitivity of 25.8%, specificity of 99.8%, positive predictive value of 80.8%, and a negative predictive value of 97.7%. MRI was concordant with US in 11 of 14 (78.5%) cases of severe forms of PAS and in three of 15 (20.0%) cases with placenta accreta.

CONCLUSION

A standardized US evaluation can be applied in a universal screening setting for the diagnosis of severe forms of PAS. MRI is a complementary examination in severe forms of PAS but seems of limited value to discriminate placenta accreta from placenta increta/percreta.

Comparison between placenta accreta scoring system, ultrasound staging, and clinical classification

Placenta accreta spectrum (PAS) is a series of disorders, which means that the placental trophoblast invades into the myometrium of the uterine wall. It is a serious obstetric complication which could be detected by ultrasound prenatally. In order to compare our placenta accreta scoring system with prenatal ultrasound staging system and International Federation of Gynecology and Obstetrics (FIGO) clinical classification, we did a retrospective study including 105 patients diagnosed with PAS disorders by operation or pathology at Peking University First Hospital, Beijing, China, between January, 2019 and December, 2020. Placenta accreta scoring system, prenatal ultrasound staging system and FIGO clinical classification were used on each patient. Basic information and clinical outcomes including gestational weeks, intraoperative hemorrhage, hysterectomy rate and blood transfusion were also counted. Both of placenta accreta scoring system, prenatal ultrasound staging system can give a rather clear prediction of placenta percreta, with their area under curve were 0.872 (95% confidential interval [CI]: 0.793-0.951) and 0.864 (95%CI: 0.779-0.949), P value were .000 compared with clinical classification. Beside for ultrasound staging system was designed for placenta previa patients, all those 3 criteria showed their relationships with preterm birth, hysterectomy rate and intraoperative bleeding. PAS scoring system also had the ability to predict a gestational week of delivery ≤34 weeks, intraoperative massive bleeding ≥2000 mL and hysterectomy at over 12 points. Our placenta accreta scoring system had good accordance with pre-operational ultrasound staging and FIGO clinical classification, with higher universality for patients without placenta previa.

Placental and Umbilical Cord Anomalies Diagnosed by Two- and Three-Dimensional Ultrasound

The aim of this review is to present a wide spectrum of placental and umbilical cord pathologies affecting the pregnancy. Placental and umbilical cord anomalies are highly associated with high-risk pregnancies and may jeopardize fetal well-being in utero as well as causing a predisposition towards poor perinatal outcome with increased fetal and neonatal mortality and morbidity. The permanent, computerized perinatology databases of different international centers have been searched and investigated to fulfil the aim of this manuscript. An extended gallery of prenatal imaging with autopsy correlation in specific cases will help to provide readers with a useful iconographic tool and will assist with the understanding and definition of this critical obstetrical and perinatological issue.

The diversity of trophoblast cells and niches of placenta accreta spectrum disorders revealed by single-cell RNA sequencing

Placenta accreta spectrum disorders (PAS) are severe pregnancy complications that occur when extravillous trophoblast cells (EVTs) invade beyond the uterine inner myometrium and are characterized by hypervascularity on prenatal ultrasound and catastrophic postpartum hemorrhage. The potential mechanisms remain incompletely understood. With single-cell RNA-sequencing analysis on the representative invasive parts and the normal part obtained from the same PAS placenta, we profiled the pathological landscape of invasive PAS placenta and deciphered an intensified differentiation pathway from progenitor cytotrophoblasts (CTBs) to EVTs via LAMB4 + and KRT6A + CTBs. In the absence of the decidua, the invasive trophoblasts of various differentiation states interacted with ADIRF + and DES + maternal stromal cells. The PAS-associated hypervascularity might be due to the enhanced crosstalk of trophoblasts, stromal cells and vascular endothelial cells. Finally, we presented an immune microenvironmental landscape of invasive PAS. The pathogenesis of PAS could be further explored with current resources for future targeted translational studies.

Variations in uterine closure technique: an institutional survey of obstetricians and implications for patient counseling and prevention of adverse sequelae

OBJECTIVES

To assess the diversity of uterine closure techniques (UCTs) among providers in one institution and evaluate concurrent consideration of adverse outcomes for patient counseling, provisional care, and prevention.

METHODS

Forty-four obstetricians at NYU Langone Health were emailed a survey of their uterine closure technique, patient counseling, and practice experience. Results were stratified by years of practice: ≤5, 5-20, and 20-40 years.

RESULTS

Thirty-nine obstetricians (88.6%) completed the survey. Among those, a blunt uterine opening was preferred by 29 (74.4%), and a mid-lower segment location was favored by 34 (87.2%). At uterine closure, the endometrium was included by 20 (51.3%), with half a centimeter or more incorporated in the myometrial closure, whereas 15 (38.5%) did not factor in the endometrium's presence. Closure duration varied from 1 to 20 min, with 21 (53.9%) lasting 1-5 min and 12 (30.8%) lasting 5-10 min. All physicians were familiar with the potential post-cesarean complications and counseled their patients accordingly; 25 (64.1%) at the first post-op visit while 14 (35.9%) did so before the next conception. Practitioners with fewer years in practice endorsed the safety of up to five consecutive cesarean births, while those with more experience approved up to ten. Thirty-two obstetricians (82.1%) stated that the risk of abnormal placentation is exclusively associated with the number of cesarean sections, whereas five (12.8%) senior obstetricians asserted that individual surgical techniques are most impactful.

CONCLUSIONS

The survey illustrates that various UCTs are performed irrespective of potential adverse sequelae and without consideration for subsequent patient counseling and care. Ongoing research must study the impact of UCT on scar healing to formulate preventive strategies for post-cesarean complications.

The maximum length of T2-dark intraplacental bands may help predict intraoperative haemorrhage in pregnant women with placenta accreta spectrum (PAS)

PURPOSE

To investigate the relationship between the maximum length of T2-dark intraplacental bands (MLTIB) and intraoperative haemorrhage in pregnant women with placenta accreta spectrum (PAS).

METHODS

Between February 2018 and February 2021, 86 pregnant women with PAS who delivered in Taizhou Hospital of Zhejiang Province and underwent preoperative magnetic resonance imaging (MRI) examination were retrospectively recruited. The presence of T2-dark intraplacental bands, placental/uterine bulge, loss of retroplacental T2-hypointense line, myometrial thinning, bladder wall interruption, focal exophytic mass, and abnormal vascularization of placental bed were recorded, and the MLTIB was measured. The relative risk ratios of the MRI findings and intraoperative bleeding were measured. Receiver operating characteristic (ROC) analysis was used to evaluate the ability of the MLTIB to help predict intraoperative haemorrhage in pregnant women with PAS.

RESULTS

Of the 86 pregnant women, 32 had intraoperative blood loss ≥ 1000 ml; of these, 18 had intraoperative blood loss ≥ 2000 ml. Abnormal vascularization of placental bed was associated with the highest relative risk ratio for the detection of intraoperative haemorrhage (RR = 10.66), followed by the presence of T2-dark intraplacental bands (RR = 8.02). The optimal cut-off of the MLTIB for predicting intraoperative haemorrhage (≥ 1000 ml) in pregnant women with PAS was 28.95 mm, and the AUC was 0.91 (sensitivity: 84%; specificity: 91%). The optimal cut-off of the MLTIB for predicting massive intraoperative haemorrhage (≥ 2000 ml) was 35.65 mm, and the AUC was 0.94 (sensitivity: 89%; specificity: 85%).

CONCLUSION

MLTIB was related to intraoperative haemorrhage in pregnant women with PAS. An MLTIB greater than 28.95 mm is an effective predictor of intraoperative haemorrhage. An MLTIB of 35.65 mm or greater strongly suggests the possibility of massive intraoperative haemorrhage.