Interobserver agreement in MRI assessment of severity of placenta accreta spectrum disorders

A novel MRI-based diagnostic model for predicting placenta accreta spectrum

Objective To develop and evaluate a diagnostic model based on MRI signs for predicting placenta accreta spectrum. Materials and Methods A total of 155 pregnant women were included in this study, randomly divided into 104 cases in the training set and 51 cases in the validation set. There were 93 Non-PAS cases, and 62 cases in the PAS group. The training set included 62 Non-PAS cases and 42 PAS cases. Clinical factors and MRI signs were collected for univariate analysis. Then, binary logistic regression analysis was used to develop independent diagnostic models with clinical relevant risk factors or MRI signs, as well as those combining clinical risk factors and MRI signs. The ROC curve analysis was used to evaluate the diagnostic performance of each diagnostic model. Finally, the validation was performed with the validation set. Results In the training set, four clinical factors (gestity, parity, uterine surgery history, placental position) and 11 MRI features (T2-dark bands, placental bulge, T2 hypointense interface loss, myometrial thinning, bladder wall interruption, focal exophytic mass, abnormal placental bed vascularization, placental heterogeneity, asymmetric placental thickening/shape, placental ischemic infarction, abnormal intraplacental vascularity) were considered as risk factors for PAS. The AUC of the clinical diagnostic model, MRI diagnostic model, and clinical + MRI model of PAS were 0.779, 0.854, and 0.874, respectively. In the validation set, the AUC of the clinical diagnostic model, MRI diagnostic model, and clinical + MRI model of PAS were 0.655, 0.728, and 0.735, respectively. Conclusion Diagnosis model based on MRI features in this study can well predict placenta accreta spectrum.

The predictive value of conventional magnetic resonance imaging combined with intravoxel incoherent motion parameters for evaluating maternal and neonatal clinical outcomes in patients with placenta accreta spectrum disorders

INTRODUCTION

We aimed to identify factors predictive of adverse maternal and neonatal outcomes in patients with placenta accreta spectrum (PAS) disorders using magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) parameters.

METHOD

Fifty-six normal singleton pregnancies at 33-39 weeks of gestation underwent MRI examination at 1.5 T. The IVIM parameters were obtained from the placenta. The correlation between the f value and postpartum hemorrhage (PPH) and between the f value and transfused units of red blood cells (RBCs) was estimated by linear regression. The correlation between various influencing factors (clinical risk factors, MRI features, and IVIM parameters) and poor outcomes was investigated using univariate and multivariate analyses.

RESULT

The interobserver agreement ranged from fair to excellent (k = 0.30-0.88). Multivariate analyses showed that previous cesarean sections, low signal intensity bands on T2WI and the D value were independent risk factors for adverse outcomes. The combination of three risk factors demonstrated the highest AUC of 0.903, with a sensitivity and specificity of 73.10 % and 96.90 %, respectively. Last, f was positively correlated with PPH and units of RBCs transfused.

DISCUSSION

Preoperative MRI features and IVIM parameters may be used to predict poor outcomes in patients with invasive placental disorders like PAS.

Evaluation of preoperative ultrasound signs associated with bladder injury during complex Cesarean delivery: case-control study

OBJECTIVE

Intraoperative hemorrhage and peripartum hysterectomy are the main complications in patients presenting with a low-lying placenta or placenta previa undergoing repeat Cesarean delivery (CD). Patients with a high probability of placenta accreta spectrum (PAS) at birth also have a higher risk of intraoperative urologic injury. The aim of this study was to evaluate the ultrasound signs and intraoperative features associated with these injuries.

METHODS

This was a retrospective case-control study of consecutive singleton pregnancies included in a prospective cohort of patients with a history of at least one prior CD and diagnosed prenatally with an anterior low-lying placenta or placenta previa at 32-36 weeks' gestation. All patients underwent investigational preoperative transabdominal and transvaginal ultrasound examination within 48 h prior to delivery. Ultrasound anomalies of uterine contour and uteroplacental vascularity, and gross anomalies of the lower uterine segment (LUS) and surrounding pelvic tissue at delivery, were recorded using a standardized protocol, which included evaluation of the extent of uterine contour anomalies. The diagnosis of PAS was established when one or more placental lobules could not be separated digitally from the uterine wall at delivery or during the gross examination of the hysterectomy or partial myometrial resection specimens, and was confirmed by histopathology. Data were compared between cases complicated by intraoperative bladder injury and controls from the same cohort matched at a 1:3 ratio by parity and the number of prior CDs using conditional logistic regression.

RESULTS

There were 16 (9.4%) patients with an intraoperative bladder injury in a cohort of 170 managed by the same multidisciplinary team during the study period. There were no patients diagnosed with ureteric or bladder trigone damage. There were 14 (87.5%) patients with a bladder injury that had histopathologic evidence of PAS at birth, including 11 (68.8%) cases described on microscopic examination as placenta increta and three (18.8%) as placenta creta. There was a significant (P = 0.03) difference between cases and controls in the distribution of intraoperative LUS vascularity, whereby the higher the number of enlarged vessels, the higher the odds of bladder injury. Multivariable regression analysis revealed that both gestational age at delivery and LUS remodeling on transabdominal ultrasound were associated with bladder injury. A higher gestational age was associated with a lower risk of injury. A higher LUS remodeling grade on transabdominal ultrasound was associated with an increased risk of bladder injury. Patients with Grade-3 remodeling (involving > 50% of the LUS) had 9-times higher odds of a bladder injury compared to patients with Grade-1 remodeling (involving < 30% of the LUS).

CONCLUSIONS

Preoperative ultrasound examination is useful in the evaluation of the risk of intraoperative bladder injury in patients with a history of prior CD presenting with a low-lying placenta or placenta previa. The larger the remodeling of the LUS on transabdominal ultrasound, the higher the risk of adverse urologic events. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal Diagnosis of Placenta Accreta Spectrum Disorders: Deep Learning Radiomics of Pelvic MRI

BACKGROUND

Diagnostic performance of placenta accreta spectrum (PAS) by prenatal MRI is unsatisfactory. Deep learning radiomics (DLR) has the potential to quantify the MRI features of PAS.

PURPOSE

To explore whether DLR from MRI can be used to identify pregnancies with PAS.

STUDY TYPE

Retrospective.

POPULATION

324 pregnant women (mean age, 33.3 years) suspected PAS (170 training and 72 validation from institution 1, 82 external validation from institution 2) with clinicopathologically proved PAS (206 PAS, 118 non-PAS).

FIELD STRENGTH/SEQUENCE

3-T, turbo spin-echo T2-weighted images.

ASSESSMENT

The DLR features were extracted using the MedicalNet. An MRI-based DLR model incorporating DLR signature, clinical model (different clinical characteristics between PAS and non-PAS groups), and MRI morphologic model (radiologists' binary assessment for the PAS diagnosis) was developed. These models were constructed in the training dataset and then validated in the validation datasets.

STATISTICAL TESTS

The Student t-test or Mann-Whitney U, χ2 or Fisher exact test, Kappa, dice similarity coefficient, intraclass correlation coefficients, least absolute shrinkage and selection operator logistic regression, multivariate logistic regression, receiver operating characteristic (ROC) curve, DeLong test, net reclassification improvement (NRI) and integrated discrimination improvement (IDI), calibration curve with Hosmer-Lemeshow test, decision curve analysis (DCA). P < 0.05 indicated a significant difference.

RESULTS

The MRI-based DLR model had a higher area under the curve than the clinical model in three datasets (0.880 vs. 0.741, 0.861 vs. 0.772, 0.852 vs. 0.675, respectively) or MRI morphologic model in training and independent validation datasets (0.880 vs. 0.760, 0.861, vs. 0.781, respectively). The NRI and IDI were 0.123 and 0.104, respectively. The Hosmer-Lemeshow test had nonsignificant statistics (P = 0.296 to 0.590). The DCA offered a net benefit at any threshold probability.

DATA CONCLUSION

An MRI-based DLR model may show better performance in diagnosing PAS than a clinical or MRI morphologic model.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

Urological complications in women undergoing Cesarean section for placenta accreta spectrum disorders: systematic review and meta-analysis

OBJECTIVE

To report on the occurrence of urological complications in women undergoing Cesarean section for placenta accreta spectrum disorders (PAS).

METHODS

MEDLINE, EMBASE and the Cochrane databases were searched electronically up to 1 November 2022. Studies reporting on the urological outcome of women undergoing Cesarean section for PAS were included. Two independent reviewers performed data extraction using a predefined protocol and assessed the risk of bias using the Newcastle-Ottawa scale for observational studies, with disagreements resolved by consensus.The primary outcome was the overall occurrence of urological complications. Secondary outcomes were the occurrence of any cystotomy, intentional cystotomy, unintentional cystotomy, ureteral damage, ureteral fistula and vesicovaginal fistula. All outcomes were explored in the overall population of women undergoing surgery for PAS. In addition, we performed subgroup analyses according to the type of surgery (Cesarean hysterectomy, or conservative surgery or management), severity of PAS at histopathology (placenta accreta/increta and placenta percreta), type of intervention (planned vs emergency) and number of cases per year. Random-effects meta-analyses of proportions were used to analyze the data.

RESULTS

There were 62 studies included in the systematic review and 56 were included in the meta-analysis. Urological complications occurred in 15.2% (95% CI, 12.9-17.7%) of cases. Cystotomy complicated 13.5% (95% CI, 9.7-17.9%) of surgical operations. Intentional cystotomy was required in 7.7% (95% CI, 6.5-9.1%) of cases, while unintentional cystotomy occurred in 7.2% (95% CI, 6.0-8.5%) of cases. Urological complications occurred in 19.4% (95% CI, 16.3-22.7%) of cases undergoing hysterectomy and 12.2% (95% CI, 7.5-17.8%) of those undergoing conservative treatment. In the subgroup analyses, urological complications occurred in 9.4% (95% CI, 5.4-14.4%) of women with placenta accreta/increta and 38.5% (95% CI, 21.6-57.0%) of those described as having placenta percreta, and included mainly cystotomy (5.5% (95% CI, 0.6-15.1%) and 22.0% (95% CI, 5.4-45.5%), respectively). Urological complications occurred in 15.4% (95% CI, 8.1-24.6%) of cases undergoing a planned procedure and 24.6% (95% CI, 13.0-38.5%) of those undergoing an emergency intervention. In subanalysis of studies reporting on ≥ 12 cases per year, the incidence of urological complication was similar to that reported in the primary analysis.

CONCLUSIONS

Women undergoing surgery for PAS are at high risk of urological complication, mainly cystotomy. The incidence of these complications was particularly high in women described as having placenta percreta at birth and in those undergoing emergency surgical intervention. The high heterogeneity between the included studies highlights the need for a standardized protocol for the diagnosis of PAS to identify prenatal imaging signs associated with the increased risk of urological morbidity at delivery. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Imaging of Acute Abdominopelvic Pain in Pregnancy and Puerperium-Part I: Obstetric (Non-Fetal) Complications

Acute abdominopelvic pain in pregnant and postpartum patients presents clinical and therapeutic challenges, often requiring quick and accurate imaging diagnosis. Ultrasound remains the primary imaging investigation. Magnetic resonance imaging (MRI) has been shown to be a powerful diagnostic tool in the setting of acute abdominal pain during pregnancy and puerperium. MRI overcomes some drawbacks of US, avoiding the ionizing radiation exposure of a computed tomography (CT) scan. Although CT is not usually appropriate in pregnant patients, it is crucial in the emergency evaluation of postpartum complications. The aim of this article is to provide radiologists with a thorough familiarity with the common and uncommon pregnancy and puerperium abdominal emergencies by illustrating their imaging appearances. The present first section will review and discuss the imaging findings for acute abdominopelvic pain of obstetric (non-fetal) etiology.

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.

Placenta accreta spectrum disorders clinical practice guidelines: A systematic review

OBJECTIVES

To objectively assess the quality of the published clinical practice guidelines (CPGs) on the management of pregnancies complicated by placenta accreta spectrum (PAS)disorders.

METHODS

MEDLINE, Embase, Scopus, and ISI Web of Science databases were searched. The following aspects related to the management of pregnancies with suspected PAS disorders were evaluated: risk factors for PAS, prenatal diagnosis, role of interventional radiology and ureteral stenting, and optimal surgical management. The assessment of risk of bias and quality assessment of the CPGs were performed using the (AGREE II) tool (Brouwers et al., 2010). To define a CPG as of good quality we adopted a cut-off score >60%.

RESULTS

Nine CPGs were included. Specific risk factors for referral were assessed by 44.4% (4/9) of CPGs, mainly consisting in the presence of placenta previa and a prior cesarean delivery or uterine surgery. About 55.6% of CPGs (5/9) suggested ultrasound assessment of women with risk factors for PAS in the second and third trimester of pregnancy and 33.3% (3/9) recommended magnetic resonance imaging (MRI); 88.9% (8/9) of CPGs recommended cesarean delivery at 34-37 weeks of gestation. There was not generally consensus on the use of interventional radiology and ureteral stenting before surgery for PAS. Finally, hysterectomy was the recommend surgical approach by 77.8% (7/9) of the included CPGs.

CONCLUSION

Most of the published CPGs on PAS are generally of good quality. There was general agreement among the different CPGs on PAS as a regard as risk stratification, timing at diagnosis and delivery but not on the indication for MRI, use of interventional radiology and ureteral stenting.

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.

Systematic review and meta-analysis on placenta accreta spectrum disorders in twin pregnancies: risk factors, detection rate and histopathology

INTRODUCTION

The occurrence of PAS has been recently associated with the presence of twin pregnancy. Aim of this review is to report the risk factors, histopathological correlation, diagnostic accuracy of prenatal ultrasound and clinical outcome of twin pregnancies complicated by placenta accreta spectrum (PAS) disorders.

EVIDENCE ACQUISITION

PubMed, Embase, Cinahl, Clinical Trial.Gov and Google Scholar databases were searched. Inclusion criteria were studies on twin pregnancies complicated by PAS. The outcomes explored were risk factors for PAS (including placenta previa, prior uterine surgery or assisted reproductive technology, ART), histopathology (placenta accreta and increta/percreta), detection rate of prenatal ultrasound and clinical outcome, including need for blood transfusion, hysterectomy, emergency or scheduled Cesarean delivery (CD), and maternal death. Random effect meta-analyses of proportions were sued to combine the data.

EVIDENCE SYNTHESIS

Two studies considering 103 pregnancies were included in this systematic review: 41.86% (95% CI 27.0-57.9) of twin pregnancies complicated by PAS disorders had a prior CD, 28.22% (95% CI 13.4-46.0) presented placenta previa and 58.14% (95% CI 42.1-73.0) of twin pregnancies were conceived by ART. 74.49% (95% CI 41.6-96.5) of PAS in twin pregnancies were placenta accreta, while 25.51% (95% CI 3.5-58.4) were placenta increta or percreta. Prenatal diagnosis of PAS in twin pregnancies was accomplished only in 27.91% (95% CI 15.3-43.7) of cases. Finally, only one study consistently reported the clinical outcome of PAS in twins. 31.67% (95% CI 20.3-45.0) of women required blood transfusion, 26.67% (95% CI 16.1-39.7) had hysterectomy, while there was no case of maternal death. 44.19% of women had an emergency CD.

CONCLUSIONS

There is still limited evidence on the clinical course of PAS disorders in twin pregnancies. Placenta previa, prior uterine surgery (mainly CD), and ART are the most commonly risk factors for PAS disorders in twins. Prenatal diagnosis of PAS in twins is lower compared to what reported in singleton. Finally, about 30% of women with a twin pregnancy complicated by PAS required blood transfusion and hysterectomy.

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.

An update of diagnostic efficacy of ultrasound and magnetic resonance imaging in the diagnosis of clinically significant placenta accreta spectrum disorders

PURPOSE OF REVIEW

Systematic screening and diagnosis of placenta accreta spectrum disorder (PAS) either by ultrasound or magnetic resonance imaging (MRI) would allow referral of high-risk women to specialized multidisciplinary teams. We aimed to report recent findings regarding the diagnostic accuracy of ultrasound and magnetic resonance imaging in the diagnosis of PAS.

RECENT FINDINGS

Recent evidence from the literature shows that both ultrasound and MRI are good tests to identify PAS in high-risk populations. Ultrasound can also be used safely to guide management decisions, concentrating greater resources in patients with the higher risk of clinically significant PAS requiring complex peripartum management. Moreover, there are increasing data showing that routine contingent screening for PAS disorders based on the finding of a placenta implanted low in the uterine cavity and previous uterine surgery is effective in a public healthcare setting. A contingent screening strategy for PAS is feasible if placental location is routinely assessed during routine scans, and may even start from the first trimester of pregnancy.

SUMMARY

Ultrasound is an effective tool to screen pregnancies at high risk of PAS. In such pregnancies, ultrasound and MRI are effective imaging modalities for guiding management.

Percreta score to differentiate between placenta accreta and placenta percreta with ultrasound and MR imaging

INTRODUCTION

The objective of this study was to assess the performance of ultrasound and magnetic resonance imaging (MRI) features in helping to classify the type of placenta accreta spectrum (PAS; accreta/increta vs percreta), alone or combined in a predictive score.

MATERIAL AND METHODS

We conducted a retrospective study in 82 pregnant women with PAS who underwent ultrasound and MRI examination of the pelvis before delivery (from an initial cohort of 185 women with PAS). We estimated the sensitivity, specificity and accuracy of MRI and ultrasound in the diagnosis of the type of PAS. We analyzed cesarean and imaging features using univariable logistic regression analysis. We constructed a nomogram to predict the risk of placenta percreta and validated it with bootstrap resampling, then used receiver operating characteristic curves to assess the performance of the model in distinguishing between placenta percreta and placenta accreta/increta.

RESULTS

Among the 82 patients, 29 (35%) had placenta accreta/increta and 53 (65%) had placenta percreta. The best features to discriminate between placenta accreta/increta and placenta percreta with ultrasound were increased vascularization at the uterine serosa-bladder wall interface (odds ratio [OR] 7.93; 95% confidence interval [CI] 2.78-24.99; p < 0.01) and the number of lacunae without a hyperechogenic halo (OR 1.36; 95% CI 1.14-1.67; p = 0.012). Concerning MRI markers, heterogeneous placenta (OR 12.89; 95% CI 3.05-89.16; p = 0.002), dark intraplacental bands (OR 12.89; 95% CI 3.05-89.16; p = 0.002) and bladder wall interruption (OR 15.89; 95% CI 4.78-73.33; p < 0.001) had a higher OR in discriminating placenta accreta/increta from placenta percreta. The nomogram yielded areas under the curve of 0.841 (95% CI 0.754-0.927) and 0.856 (95% CI 0.767-0.945), after bootstrap resampling, for the accurate prediction of placenta percreta.

CONCLUSIONS

The nomogram we developed to predict the risk of placenta percreta among patients with PAS had good discriminative capabilities. This performance and its impact on maternal morbidity should be confirmed by future prospective studies.

Quality of surgical management of placenta accreta spectrum in a tertiary center in Sri Lanka: baseline study for quality improvement project: problems and solutions

Introduction

Placenta accreta spectrum (PAS) is associated with a multitude of maternal and fetal complications. Events related to its management have resulted in significant psychological morbidity, with lifelong consequences which warrant continuous support to cope with their lives. The objective of the study is to highlight the importance of multidisciplinary holistic care and explore room for improvement in the provision of care for women with PAS.

Methods

Our study was conducted on deliveries complicated with PAS from January 2019 to June 2021. 27 women were diagnosed with PAS during this period and received treatment. Impact of life event scale- revised (IES-R) and short form health survey-36(SF-36) questionnaires were administered to assess the impact of PAS on their lives. In depth interviews were conducted with the women. A multidisciplinary team meeting was later conducted to formulate a comprehensive care plan for women with PAS.

Results

The response rate was 96.2%. Mean age of the sample is 34.1 years (SD 4.3). Interval to current pregnancy varies from 0.6 years to 10 years with mean of 4.6 years. Mean gestational age of diagnosis of PAS was 25.4(SD 6.7) weeks. The care bundle provided for women with PAS was evaluated in all cases.

Surgery was conducted electively in 82% of patients. Blood transfusions were noted in 85%. Mean pre-operative stay was 9.5 days (SD 8.3) and mean post-operative stay was 8.8 days (SD 8). Total hospital stay ranged from 6 to 48 days (mean 19.5 days, SD 11.4).

IES-R scores were significant in 4/26 patients. There was no correlation with the interval from the surgery with any of the subscales or with the total scores. The lapsed time after the surgery had a significant correlation with physical functioning and pain domains of the SF-36 questionnaire.

Description of the experience, loss of femininity with loss of the uterus, concerns and fears about the future and measures to improve the quality of care were the themes identified and described.

A multidisciplinary team meeting, consisting of consultant obstetricians performing surgery for PAS, anesthetists, hematologist, transfusion medicine specialist, urologist, physiotherapist, nutritionist and nursing officers from ICU and wards, was held and their contributions helped to map out a definitive care plan.

Conclusions

PAS is associated with long term physical and psychological morbidity. Continuous support through quarterly clinic visits and telephone conversations may alleviate the psychological trauma. However, some physical disabilities may be lifelong and life changing. Importance of reducing primary caesarean section and promoting trial of labour after caesarean delivery should be promoted among patients and caregivers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04840-7.

Texture analysis of myometrium-derived T2WI in the evaluation of placenta increta: An observational retrospective study

INTRODUCTION

MRI has demonstrated its potential in the diagnosis of placenta percreta. Texture analysis is a novel technique to quantify tissue heterogeneity. The study aimed to evaluate the feasibility of using texture analysis based on myometrium-derived T2WI to differentiate placenta accreta from increta.

METHODS

Participants with MRI and clinical or histopathological diagnosis of placenta increta were retrospectively enrolled. Texture analysis of T2WI was implemented on normal myometrium and placenta increta by MaZda software. With the Fisher discriminant method, parameter selection and reduction were done automatically. Multivariate analysis was used for the comparison of response variables between two groups. The contours of multivariable average vectors were compared using profile analysis. Two-step clustering was performed to assess the importance of parameters.

RESULTS

There were a total of 23 participants (median age 29 years, range 22-43 years). The pixel intensity distribution was narrow and wide in two first-order histograms taken from normal myometrium and placenta increta, respectively. Multivariate analysis showed nine second-order parameters derived from the histogram were statistically significant (P < 0.05). The results of two-step clustering indicated that three second-order parameters (Mean, Percentile 90%, and Percentile 99%) were important (predictor importance > 0.8). Multivariate analysis of three second-order parameters further showed they were different between normal myometrium and placenta increta.

DISCUSSION

Texture analysis based on myometrium-derived T2WI may be a useful add-on to MRI in diagnosing placenta increta.

TRIAL REGISTRATION

Registration number: ChiCTR2000038604 and name of registry: Evaluation of diagnostic accuracy of MRI multi-parameter imaging combined with texture analysis for placenta accreta spectrum disorders (PAD).

Monoexponential, biexponential and diffusion kurtosis MR imaging models: quantitative biomarkers in the diagnosis of placenta accreta spectrum disorders

BACKGROUND

To investigate the diagnostic value of monoexponential, biexponential, and diffusion kurtosis MR imaging (MRI) in differentiating placenta accreta spectrum (PAS) disorders.

METHODS

A total of 65 patients with PAS disorders and 27 patients with normal placentas undergoing conventional DWI, IVIM, and DKI were retrospectively reviewed. The mean, minimum, and maximum parameters including the apparent diffusion coefficient (ADC) and exponential ADC (eADC) from standard DWI, diffusion kurtosis (MK), and mean diffusion coefficient (MD) from DKI and pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) from IVIM were measured from the volumetric analysis and compared between patients with PAS disorders and patients with normal placentas. Univariate and multivariated logistic regression analyses were used to evaluate the value of the above parameters for differentiating PAS disorders. Receiver operating characteristics (ROC) curve analyses were used to evaluate the diagnostic efficiency of different diffusion parameters for predicting PAS disorders.

RESULTS

Multivariate analysis demonstrated that only D mean and D max differed significantly among all the studied parameters for differentiating PAS disorders when comparisons between accreta lesions in patients with PAS (AP) and whole placentas in patients with normal placentas (WP-normal) were performed (all p < 0.05). For discriminating PAS disorders, a combined use of these two parameters yielded an AUC of 0.93 with sensitivity, specificity, and accuracy of 83.08, 88.89, and 83.70%, respectively.

CONCLUSION

The diagnostic performance of the parameters from accreta lesions was better than that of the whole placenta. D mean and D max were associated with PAS disorders.

Magnetic resonance imaging and previous cesarean section in placenta accrete spectrum disorder: Predictor model

OBJECTIVE

To evaluate objective criteria of Magnetic Resonance Imaging (MRI) of Placenta Accreta Spectrum disorder (PAS) analyzing interobserver agreement and to derive a model including imaging and clinical variables to predict PAS.

METHODS

A retrospective review including patients submitted to MRI with suspicious findings of PAS on ultrasound. Exclusion criteria were lack of pathology or surgical information and missing or poor-quality MRI. Two radiologists analyzed six MRI features, and significant clinical data were also recorded. PAS confirmed on pathology or during intraoperative findings were considered positive for the primary outcome. Variables were tested through logistic regression models.

RESULTS

Final study included 96 patients with a mean age of 33 years and 73.0% of previous C-sections. All MRI features were significantly associated with PAS for both readers. After logistic regression fit, including MRI signs with a moderate or higher interobserver agreement, intraplacental T2 dark band was the most significant radiologic criteria, and ROC analysis resulted in an AUC = 0.782. After including the most relevant clinical data (previous C-section) to the model, the ROC analysis improved to an AUC = 0.893.

CONCLUSION

Simplified objective criteria on MRI, including intraplacental T2 dark band associated with clinical information of previous C-sections, had the highest accuracy and was used for a predictive model of PAS.

Diagnostic performance of radiologists with different levels of experience in the interpretation of MRI of the placenta accreta spectrum disorder

OBJECTIVES

There have been no investigations on the association between previous abdominopelvic MRI experience without placental MRI experience and diagnostic accuracy of placenta accreta spectrum (PAS). To evaluate the diagnostic performance of radiologists with different experience levels in interpreting PAS-related MRI findings.

METHODS

This retrospective study included 60 women who underwent MRI for placental assessment between 2016 and 2020. MR images were reviewed by four radiologists who were blinded to the clinical outcomes and had different experience levels in interpreting PAS-related MRI findings. The radiologists' diagnostic performance was evaluated according to the pathologic and surgical outcomes. Simple κ statistics were calculated to determine agreement among the radiologists.

RESULTS

Of 60 women, 46 were diagnosed with PAS. The maternal age mean ± SD was 33.0 years ± 5.0 for the PAS absent group and 36.0 ± 4.3 for the PAS present group (p = 0.013). Overall, the most experienced radiologist had the highest sensitivity (100%, 95% confidence interval (CI): 92.3-100%) and NPV (100%, 95% CI: 63.1-100%) in PAS diagnoses. However, the PPV and specificity were independent of experience. The most experienced radiologist had the highest diagnostic accuracy in PAS (90%, 95% CI: 79.5-96.2%) and placenta percreta (95%, 95% CI: 86.1-99.0%). There was a strong association between definitive PAS diagnoses and the highest experience level. The κ values for the interobserver agreement regarding PAS diagnoses were 0.67 for the most experienced radiologist (p < 0.001) and 0.38, 0.40, and 0.43 for the other radiologists (p = 0.001) and regarding placenta percreta diagnoses were 0.87 for the senior radiologist (p < 0.001) and 0.63, 0.57, and 0.62 for the other radiologists (p < 0.001).

CONCLUSION

Previous experience in interpreting PAS-related MRI findings plays a significant role in accurately interpreting such imaging findings. Previous abdominopelvic MRI experience without specific placental MRI experience did not improve diagnostic performance.

ADVANCES IN KNOWLEDGE

We believe that our study makes a significant contribution to the literature and that this paper will be of interest to the readership of your journal because to the best of our knowledge, this study is the first in which the correlation between previous experience in abdominopelvic MRI with no specific experience in PAS-related MRI and diagnostic accuracy of radiologists has been explored. Our results could aid in setting up specialized multidisciplinary teams to assist women with PAS disorders.

MRI based morphological examination of the placenta

Ultrasound is widely used as the initial diagnostic imaging modality during pregnancy with both high spatial and temporal resolution. Although MRI in pregnancy has long focused on the fetus, its use in placental imaging has greatly increased over recent years. In addition to the possibilities of evaluating function, MRI with a wide field of view and high contrast resolution allows characterization of placental anatomy, particularly in situations that are difficult to specify with ultrasound, especially for suspected placenta accreta. MRI also appears to be a particularly useful examination for the anatomical evaluation of the placenta independent of maternal body habitus or fetal position. Indeed, surprisingly little attention is paid to the placenta in MRI when the indication for the examination is fetal. Thus, some aspects of the placenta seem to us to be important to be recognized by the radiologist and to be described on the MRI report. In this review, we will describe MRI sequences used for, and common features seen in, imaging of i) the normal placenta, ii) abnormal aspects of the placenta that should be identified on MRI performed for fetal reason, and iii) placental anomalies for which placental MRI may be indicated.

Prediction for Postpartum Hemorrhage of Placenta Previa Patients through MRI Using Self-Adaptive Edge Detection Algorithm

The study aimed to explore the application value of MRI images based on the optimized self-adaptive edge detection algorithm in the diagnosis of placenta previa and in the prediction of postpartum hemorrhage. Specifically, a self-adaptive edge detection algorithm was constructed based on optimized edge operators, with the nearest scale parameters analyzed. It was then used to process the MRI images of 36 patients with placenta previa. MRI images of different types of placenta previa were analyzed. The results found that the placenta of the complete placenta previa was attached to the lower wall of the uterus and covered the internal cervix in U shape, and the placenta adhered to the anterior and lower wall of the uterus, with widespread placenta accreta noted. With the results of cesarean section as the standard, it was observed that 2 cases of complete placenta previa were diagnosed as partial placenta previa. The diagnostic accuracy rate was 94.44%, which was not notably different from the results of cesarean section (p > 0.05). The postpartum hemorrhage rate and hysterectomy rate of complete placenta previa were higher than partial placenta previa and marginal placenta previa, and the difference was notable (p < 0.05), but no notable differences were noted in placenta adhesion, placenta accreta, neonatal death, and neonatal asphyxia between the three types of placenta previa (p > 0.05). The incidence of thinned myometrium, placenta penetrating the cervix, placenta accreta, and uneven placental signal in patients with postpartum hemorrhage was higher versus those without postpartum hemorrhage, and the difference was notable (p < 0.05). In a word, MRI images based on the self-adaptive edge detection algorithm can clearly show the status of placenta previa and exhibit better diagnosis effects and a higher accuracy rate. The thinned myometrium, the placenta penetrating the cervix, placenta accreta, and uneven placental signal may be the related risk factors for postpartum hemorrhage in patients with placenta previa.

Risk factors, histopathology and diagnostic accuracy in posterior placenta accreta spectrum disorders: systematic review and meta-analysis

OBJECTIVE

To elucidate the risk factors, histopathological correlations and diagnostic accuracy of prenatal imaging in pregnancies complicated by posterior placenta accreta spectrum (PAS) disorders.

METHODS

MEDLINE, EMBASE and CINAHL were searched for studies reporting on women with posterior PAS. Inclusion criteria were women with posterior PAS confirmed either at surgery or on histopathological analysis. The outcomes explored were risk factors for posterior PAS, histopathological correlation and the diagnostic accuracy of ultrasound and magnetic resonance imaging (MRI) in detecting posterior PAS. Random-effects meta-analysis of proportions was used to analyze the data.

RESULTS

Twenty studies were included. Placenta previa was present in 92.8% (107/114; 17 studies) of pregnancies complicated by posterior PAS, while 76.1% (53/88; 11 studies) of women had had prior uterine surgery, mainly a Cesarean section (CS) or curettage and 82.5% (66/77; 10 studies) were multiparous. When considering histopathological analysis in women affected by posterior PAS, 77.5% (34/44; 11 studies) had placenta accreta, 19.5% (8/44; 11 studies) had placenta increta and 9.3% (2/44; 11 studies) had placenta percreta. Of the cases of posterior PAS disorder, 52.4% (31/63; 12 studies) were detected prenatally on ultrasound, while 46.7% (32/63; 12 studies) were diagnosed only at birth. When exploring the distribution of the classic ultrasound signs of PAS, placental lacunae were present in 39.0% (12/30; seven studies), loss of the clear zone in 41.1% (13/30; seven studies) and bladder-wall interruption in 16.6% (4/30; seven studies) of women, while none of the included cases showed hypervascularization at the bladder-wall interface. When assessing the role of MRI in detecting posterior PAS, 73.5% (26/32; 11 studies) of cases were detected on prenatal MRI, while 26.5% (6/32; 11 studies) were discovered only at the time of CS.

CONCLUSIONS

Placenta previa, prior uterine surgery and multiparity represent the most commonly reported risk factors for posterior PAS. Ultrasound had a very low diagnostic accuracy in detecting these disorders prenatally. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Correlation of placental MR imaging signs and pathologic diagnosis of placenta accreta spectrum: Retrospective single center case series

INTRODUCTION

Alongside initial screening obstetric US, use of placental MRI has been increasing in the last few decades to aid with antenatal diagnosis and delivery planning in Placenta Accreta Spectrum (PAS). The aim of this study was to determine if the MRI pathophysiological sign subcategories described in the current literature can predict the severity of pathologic diagnosis.

METHODS

Institutional imaging records were reviewed for placental MRIs performed for suspicion of PAS in the last decade. Electronic health records were searched for patient history and pathology. The 59 MRI studies were reviewed using the 11 MRI signs described by the SAR and ESUR joint consensus statement. Further breakdown of the signs was divided by underlying pathophysiologic subcategories including gross morphologic, interface and tissue architecture signs.

RESULTS

Pathologic diagnosis yielded 34 cases: accreta 4/34, incerta 14/34, percreta 10/34 and normal 6/34. Of the accreta cases all of them demonstrated at least two interface and half of the cases had tissue architecture signs, 13/14 increta cases demonstrated interface signs and 12/14 demonstrated tissue architecture signs, 9/10 percreta cases had two interface and at least six demonstrated three tissue architecture signs. Statistical analysis showed significant difference between pathologic diagnosis and the number of positive interface signs with p = 0.02.

DISCUSSION

Interface signs were the most objective and sensitive MRI subcategory. Statistical analysis determined there was a significant difference between PAS diagnosis and number of interface signs present. This subcategory has the most overlap with classic US signs which are traditionally used before MRI referral.

Role of Ultrasound and MRI in Diagnosis of Severe Placenta Accreta Spectrum Disorder: An Intraindividual Assessment With Emphasis on Placental Bulge

Background: The placental bulge sign (focal area of myometrial-placental bulging beyond the normal uterine contour) on ultrasound (US) or MRI is postulated to represent deeper venous invasion in placental accreta spectrum (PAS) disorder and may represent severe PAS. Objective: To evaluate the diagnostic performance and interobserver agreement of US and MRI features for diagnosis of severe PAS, with an emphasis on the placental bulge sign. Method: This retrospective study included 62 pregnant women (mean age 33.2±5.5 years) with clinically suspected PAS who underwent both US and MRI. Five independent reviewers (two maternal-fetal medicine specialists for US; three abdominal radiologists for MRI) independently reviewed images for the given modality, blinded to the final diagnosis, and recorded presence of a range of findings (nine on US, eight on MRI) including placental bulge. Intraoperative and pathologic findings were used to separate patients into those with and without severe PAS, based on International Federation of Gynaecology and Obstetrics classification. Diagnostic performance of US and MRI findings for severe PAS were evaluated; multivariable logistic regression was performed; and interobserver agreement was assessed. Results: A total of 58.1% (36/62) of patients had severe PAS. On US, the finding with highest accuracy for severe PAS was placental bulge (85.5%), which was associated with sensitivity of 91.7% and specificity of 76.9%. On MRI, the finding with highest accuracy was also placental bulge (90.3%), which was associated with sensitivity of 94.4% and specificity of 84.6%. At multivariable regression, placental bulge was an independent predictor of severe PAS for US [odds ratio (OR)=8.94; p=.02] and MRI (OR=45.67; p=.003). Interobserver agreement analysis demonstrated kappa for placental bulge of 0.48 for MRI and 0.40 for US. Given wide 95% CIs, differences among features for a given modality as well as differences between modalities were not statistically significant. Conclusion: The findings suggest strong performance of placental bulge in diagnosing severe PAS on both US and MRI, with potentially relatively stronger performance on MRI. Nonetheless, interobserver agreement remains suboptimal on both modalities. Clinical impact: Accurate prenatal diagnosis of severe PAS by imaging could help guide maternal counseling and selection between hysterectomy and uterine-preserving surgery.

The clinical utility of magnetic resonance imaging as an adjunct to ultrasound in the diagnosis of placenta accreta spectrum disorders

OBJECTIVES

To determine if the use of magnetic resonance imaging (MRI) changes the diagnosis of placenta accreta spectrum (PAS) made on prenatal ultrasound (US) leading to an improvement in clinical outcomes.

METHODS

This was a retrospective chart review of all patients with evidence of PAS on US from 2012 to 2018 in one tertiary care medical center with subsequent use of MRI of the uterus to confirm diagnosis. The type of PAS classified by imaging was compared between US and MRI, with a final diagnosis made using histology. Outcomes that were analyzed included the following: 1) MRI correctly changed diagnosis, 2) MRI incorrectly downgraded diagnosis, 3) MRI incorrectly upgraded diagnosis, and 4) MRI did not change diagnosis. A T-test and Chi-squared test were performed to compare the clinical outcomes of patients with an upgraded diagnosis by MRI to those whose diagnosis was downgraded or stayed the same.

RESULTS

Forty-one patients received an MRI to validate the diagnosis of PAS after ultrasound and are included in the analysis. MRI changed the diagnosis in 36.6% (15/41) patients, correctly changing the diagnosis in 22% (9/41) and incorrectly upgrading the diagnosis in 14.6% (6/41). Patients whose diagnosis was upgraded by MRI (either correctly or incorrectly) were more likely to deliver earlier compared to those who were either downgraded or had no change in their diagnosis [33. 2 ± 3. 5 weeks vs 35. 2 ± 2. 9 weeks, p = 0.05]. Patients who were upgraded were more likely to have interventional radiology and/or urology involvement at the time of delivery [91.7% (11/12) vs 25. 9% (7/27), p = 0.001]. There were no complications from these procedures.

CONCLUSION

The use of MRI incorrectly changed the diagnosis as much as it correctly changed the diagnosis of PAS after US. MRI should not be used routinely as a clinical adjunct to ultrasound in the diagnosis of placenta accreta spectrum.

Radical surgery including the role of an interval hysterectomy

The incidence of placenta accrete spectrum (PAS) disorders is increasing worldwide. Pregnancies complicated by PAS are at a high risk of intrapartum surgical complications, mainly due to severe maternal hemorrhage, potentially leading to death, thus highlighting the need for a tailored an appropriate surgical management for these women. Despite its clinical relevance, there are still unanswered questions regarding the surgical management of women with PAS. Hysterectomy has been considered as the gold standard for the surgical treatment of these women. However, the surgical approach has not yet been standardized, and several conservative surgical procedures such as the Triple P Procedure are also being performed for PAS. Interventional radiology techniques have been demonstrated to reduce the risk of severe blood loss in women with postpartum hemorrhage, but their role in the management of women with PAS has not yet been fully defined. The aim of this chapter is to provide an up-to-date insight on the radical surgical approach to adopt during cesarean delivery in pregnancies complicated by PAS disorders.

Outcome of cesarean scar pregnancy according to gestational age at diagnosis: A systematic review and meta-analysis

OBJECTIVE

The association between the most severe types of placenta accreta spectrum disorders and caesarean scar pregnancy (CSP) poses the question of whether early diagnosis may impact the clinical outcome of these anomalies. The aim of this study is to report the outcome of cesarean scar pregnancy (CSP) diagnosed in the early (≤9 weeks) versus late (>9 weeks) first trimester of pregnancy.

STUDY DESIGN

Medline, Embase and Clinicaltrail.gov databases were searched. Studies including cases of CSP with an early (≤9 weeks of gestation) compared to a late (>9 weeks) first trimester diagnosis of CSP, followed by immediate treatment, were included in this systematic review. The primary outcome was a composite measure of severe maternal morbidity including either severe first trimester bleeding, need for blood transfusion, uterine rupture or emergency hysterectomy. The secondary outcomes were the individual components of the primary outcome. Random-effect meta-analyses were used to combine data.

RESULTS

Thirty-six studies (724 women with CSP) were included. Overall, composite adverse outcome complicated 5.9 % (95 % CI 3.5-9.0) of CSP diagnosed ≤9 weeks and 32.4 % (95 % CI 15.7-51.8) of those diagnosed >9 weeks. Massive hemorrhage occurred in 4.3 % (95 % CI 2.3-7.0) of women with early and in 28.0 % (95 % CI 14.1-44.5) of those with late first trimester diagnosis of CSP, while the corresponding figures for the need for blood transfusion were 1.5 % (95 % CI 0.6-2.8) and 15.8 % (95 % CI 5.5-30.2) respectively. Uterine rupture occurred in 2.5 % (95 % CI 1.2-4.1) of women with a prenatal diagnosis of CSP ≤ 9 weeks and in 7.5 % (95 % CI 2.5-14.9) of those with CSP > 9 weeks, while an emergency intervention involving hysterectomy was required in 3.7 % (95 % CI 2.2-5.4) and 16.3 % (95 % CI5.9-30.6) respectively. When computing the risk, early diagnosis of CSP was associated with a significantly lower risk of composite adverse outcome, (OR: 0.14; 95 % CI 0.1-0.4 p < 0.001).

CONCLUSIONS

Early first trimester diagnosis of CSP is associated with a significantly lower risk of maternal complications, thus supporting a policy of universal screening for these anomalies in women with a prior cesarean delivery although the cost-effectiveness of such policy should be tested in future studies.