Differentiating placenta accreta spectrum from scar dehiscence with underlying, non-adherent placenta: A systematic review of scoring systems and primary data analysis.

INTRODUCTION: Accurate discrimination between placenta accreta spectrum (PAS) and scar dehiscence with underlying non-adherent placenta is challenging both on prenatal ultrasound and intraoperatively. This can lead to overdiagnosis of PAS and unnecessarily aggressive management of scar dehiscence which increases the risk of morbidity. Several scoring systems have been published which combine clinical and ultrasound information to help diagnose PAS in women at high risk. This research aims to provide insights into the reliability and utility of existing accreta scoring systems in differentiating these two closely related but different conditions to contribute to improved clinical decision making and patient outcomes. MATERIAL AND METHODS: A literature search was performed in four electronic databases. The references of relevant articles were also assessed. The articles were then evaluated according to the predefined inclusion criteria. Primary data for testing each scoring system were obtained retrospectively from two hospitals with specialized PAS services. Each scoring system was used to evaluate the predicted outcome of each case. RESULTS: The literature review yielded 15 articles. Of these, eight did not have a clearly described diagnostic criteria for accreta, hence were excluded. Of the remaining seven studies, one was excluded due to unorthodox diagnostic criteria and two were excluded as they differed from the other systems hindering comparison. Four scoring systems were therefore tested with the primary data. All the scoring systems demonstrated higher scores for high-grade PAS compared to scar dehiscence (p < 0.001) with an excellent Area Under the receiver operator characteristic Curve ranging from 0.82 (95% CI 0.71-0.92) to 0.87 (95% CI 0.79-0.96) in differentiating between these two conditions. However, no statistically significant differences were noted between the low-grade PAS and scar dehiscence on all scoring systems. CONCLUSIONS: Most published scoring systems have no clearly defined diagnostic criteria. Scoring systems can differentiate between scar dehiscence with underlying non-adherent placenta from high-grade PAS with excellent diagnostic accuracy, but not for low-grade PAS. Hence, relying solely on these scoring systems may lead to errors in estimating the risk or extent of the condition which hinders preoperative planning.

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

BACKGROUND: Prenatal ultrasound discrimination between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta is challenging both prenatally and intraoperatively, which often leads to overtreatment. In addition, accurate prenatal prediction of surgical difficulty and morbidity in placenta accreta spectrum is difficult, which precludes appropriate multidisciplinary planning. The advent of advanced 3-dimensional volume rendering and contrast enhancement techniques in modern ultrasound systems provides a comprehensive prenatal assessment, revealing details that are not discernible in traditional 2-dimensional imaging. OBJECTIVE: This study aimed to evaluate the use of 3-dimensional volume rendering ultrasound techniques in determining the severity of placenta accreta spectrum and distinguishing between placenta accreta spectrum and scar dehiscence with underlying nonadherent placenta. STUDY DESIGN: A prospective, cohort study was conducted between July 2022 and July 2023 in the fetal medicine unit of Dr Soetomo Academic General Hospital, Surabaya, Indonesia. All pregnant individuals with anterior low-lying placenta or placenta previa with a previous caesarean section who were referred with suspicion of placenta accreta spectrum were consented and screened using the standardised 2-dimensional and Doppler ultrasound imaging. Additional 3-dimensional volumes were obtained from the sagittal section of the uterus with a filled urinary bladder. These were analyzed by rotating the region of interest to be perpendicular to the uterovesical interface. The primary outcomes were the clinical and histologic severity in the cases of placenta accreta spectrum and correct diagnosis of dehiscence with nonadherent placenta underneath. The strength of association between ultrasound and clinical outcomes was determined. Multivariate logistic regression analyses and diagnostic testing of accuracy were used to analyze the data. RESULTS: A total of 70 patients (56 with placenta accreta spectrum and 14 with scar dehiscence) were included in the analysis. Multivariate logistic regression of all 2-dimensional and 3-dimensional signs revealed the 3-dimensional loss of clear zone (P<.001) and the presence of bridging vessels on 2-dimensional Doppler ultrasound (P=.027) as excellent predictors in differentiating scar dehiscence and placenta accreta spectrum. The 3-dimensional loss of clear zone demonstrated a high diagnostic accuracy with an area under the curve of 0.911 (95% confidence interval, 0.819-1.002), with a sensitivity of 89.3% (95% confidence interval, 78.1-95.97%) and specificity of 92.9% (95% confidence interval, 66.1-99.8%). The presence of bridging vessels on 2-dimensional Doppler demonstrated an area under the curve of 0.848 (95% confidence interval, 0.714-0.982) with a sensitivity of 91.1% (95% confidence interval, 80.4-97.0%) and specificity of 78.6% (95% confidence interval, 49.2-95.3%). A subgroup analysis among the placenta accreta spectrum group revealed that the presence of a 3-dimensional disrupted bladder serosa with obliteration of the vesicouterine space was associated with vesicouterine adherence (P<.001). CONCLUSION: Three-dimensional volume rendering ultrasound is a promising tool for effective discrimination between scar dehiscence with underlying nonadherent placenta and placenta accreta spectrum. It also shows potential in predicting the clinical severity with urinary bladder involvement in cases of placenta accreta spectrum.

Urinary tract injuries during surgery for placenta accreta spectrum disorders.

OBJECTIVE: The main purpose of this study was to report the incidence of lower urinary tract injuries (UTI) during cesarean section (CS) hysterectomy in cases of Placenta Accreta Spectrum (PAS) disorders. Study design Retrospective analysis including all women with a prenatal diagnosis of PAS between January 2010 and December 2020. A dedicated multidisciplinary team was involved to define a tailored management for each patient. All relevant demographic parameters, risk factors, degree of placental adhesion, type of surgery, complications and operative outcomes were reported. RESULTS: One hundred and fifty-six singleton gestations with a prenatal diagnosis PAS were included in the analysis. 32.7% of cases were classified as PAS 1 (grade 1-3a FIGO classification), 20.5% as PAS 2 (grade 3b FIGO classification) and 46.8% as PAS 3 (grade 3c FIGO classification). A CS hysterectomy was performed in all cases. Surgical complication occurred in seventeen cases (0% in PAS 1, 12.5% in PAS 2 cases and in 17.8% in PAS 3). The incidence of UTI in our series was 7.6% in all women with PAS, including 8 cases of bladder and 12 of ureteral lesion, and 13.7 % in those with PAS 3 only. CONCLUSION: Despite advances in prenatal diagnosis and management, surgical complications, mainly those involving the urinary system, still occur in a significant proportion of women undergoing surgery for PAS. The findings from this study highlight the need for a multidisciplinary management of women with PAS in centers with high expertise in prenatal diagnosis and surgical management of these conditions.

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.

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.

The MRI estimations of placental thickness and cervical length correlate with postpartum hemorrhage (PPH) in patients with risk for placenta accreta spectrum (PAS) disorders.

INTRODUCTION: This study aims to identify whether placental thickness and cervical length measured by MRI correlate with postpartum hemorrhage (PPH) in patients at high risk for placenta accreta spectrum (PAS) disorders. METHODS: The placental thickness and cervical length of 200 patients from October 2017 to October 2021 were retrospectively measured. The mid-sagittal plane of the placentas was measured by 2 independent radiologists using MRI. Partial correlation analysis was used to characterize the correlation between placental thickness, cervical length and estimated blood loss during surgery. The correlation between clinical features, placental thickness, cervical length and PPH was evaluated with univariate and multivariate analyses. A nomogram was constructed based on the logistic regression. RESULTS: Placental thickness was positively correlated with the estimated blood loss during delivery, while cervical length had a negative correlation with it, based on the adjustment for gestational age. Multivariate analyses revealed that prior cesarean section, placenta previa, increased placental thickness(≧4.35 cm) and short cervical length（< 3.05 cm） were independent risk factors for PPH. When the 4 risk factors were combined together, the AUC was the highest, 0.773 (95%CI 0.707-0.840). DISCUSSION: Placental thickness and cervical length correlated with PPH. The nomogram constructed based on prior cesarean section, placenta previa, placental thickness and cervical length can be used to recognize patients with a higher risk of PPH.

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.

Correlation of placental thickness and PAS disorders: findings from MRI.

OBJECTIVE: To identify if placental thickness measured from MRI images correlates with placenta accreta spectrum (PAS) disorders. METHODS: Placental thickness of 245 patients was retrospectively measured from October 2016 to March 2020. The measurement was made at the thickest portion of the placenta on the mid-sagittal plane of the placenta from MRI by two independent radiologists. Surgical report and pathology of the delivered placenta were used as a reference standard. Association between clinical features, placental thickness, and PAS disorders was evaluated with univariate and multivariate analyses. The inter-reader and intra-reader reproducibility of the measurements and receiver operating characteristic curve analysis were also performed. RESULTS: Placental thickness was significantly higher in patients with PAS disorders (3.45 cm) than that in patients without PAS disorders (2.90 cm) (p < 0.05). Multivariate analyses revealed that prior cesarean section, placenta previa, and placental thickness > 4 cm were independent risk factors for PAS disorders. The inter-reader and intra-reader reproducibility of placental thickness measurement were 0.979 (95% CI 0.960-0.989) and 0.981 (95% CI 0.9640-0.990), respectively. CONCLUSION: The reproducibility of the measurement made from MRI images was high between two radiologists. Patients with PAS disorders had increased placental thickness. Placental thickness > 4 cm correlated with PAS disorders.

How to set up a regional specialist referral service for Placenta Accreta Spectrum (PAS) disorders?

There has been an approximately fivefold increase in the incidence of placenta accreta spectrum (PAS) disorders during the last 30 years, believed to be secondary to increasing Caesarean section rates. PAS disorder is associated with significantly increased maternal morbidity and mortality worldwide. Antenatal diagnosis by foetal medicine teams that have a special expertise to diagnose PAS disorder by the use of ultrasound scan, and a dedicated, highly specialised multidisciplinary team (MDT) comprising surgeons who are skilled in complex pelvic surgery and obstetric anaesthetists who have an expertise in high-risk obstetric anaesthesia, supported by haematology, operating theatre, interventional radiology, midwifery, neonatology, high-dependency and intensive care teams have been recommended to improve maternal and perinatal outcomes. Setting up a specialist MDT regional referral service, PAS involves collaboration with all stakeholders, ensuring appropriate funding, developing MDT care pathways, continuously auditing patient outcomes and disseminating knowledge through research, innovation, education and publications.

Uterine conservation in placenta accrete spectrum (PAS) disorders: A retrospective case series: Is expectant management beneficial in reducing maternal morbidity?

OBJECTIVE: To examine whether expectant management confers any benefit on operative morbidity for the management of placenta accrete spectrum (PAS) disorders. STUDY DESIGN: This was a single center retrospective cohort study at a tertiary referral center In Singapore. Women with PAS disorder between January 2006 and December 2017 were identified from the hospital register. Antenatal features, surgical factors and post-operative morbidity were compared between women having caesarean hysterectomy, those having caesarean section with placental removal and women having expectant management, defined as caesarean section with retention of placenta using the student's t and Chi square tests. The natural course, complications and preservation of fertility were examined for women having expectant management. RESULTS: Ninety women with PAS were included. The incidence of PAS was 0.064 %. Mean gestational age (GA) at diagnosis was 26.4 weeks. Elective and emergency deliveries were performed at 36.7 and 32.4 weeks respectively (p = <0.0001). Caesarean hysterectomy, Caesarean section with placenta removal and expectant management (EM) were performed in 51(56.7 %),16(17.8 %) and 23(25.6 %) women respectively. The mean blood loss (MBL) and surgical time for EM were significantly lower than those for caesarean hysterectomy 0.52 L vs 3.17 L (p < 0.0001) and 70.8 min vs 171.6 min (p < 0.0001). The advantage of lower blood loss with expectant management persisted even after blood loss at delayed hysterectomy was considered (1284.09 mL vs 3168.72 mL (p-value <0.0001)). Uterine preservation with EM was successful in 61 % (14/23) women. Although nine women (39 %) in this group needed hysterectomy most complications were minor and presented within three months. The mean follow up overall was 13 months. CONCLUSION: Traditionally caesarean hysterectomy has been the main surgical approach for PAS. Our study consolidates existing evidence for expectant management being an option for a select group of patients to avoid complications associated with hysterectomy and allow uterine preservation.

The role of ultrasound in prediction of intra-operative blood loss in cases of placenta accreta spectrum disorders.

PURPOSE: To assess the value of various grey-scale ultrasound, 2D color Doppler, and 3D power Doppler sonographic markers in predicting major intraoperative blood loss during planned cesarean hysterectomy for cases diagnosed with placenta accreta spectrum (PAS) disorders. METHODS: 50 women diagnosed with PAS were scanned the day before planned delivery and hysterectomy for various sonographic markers indicative of placental invasion. These women were then later divided according to blood loss in two groups: group A (minor hemorrhage, < 2500 ml), and group B (major hemorrhage, > 2500 ml), and the data were analyzed. RESULTS: The odds ratio (OR) for major hemorrhage was as follows for the following sonographic markers: 'number of lacunae > 4' OR 3.8 95% CI (1.0-13.8) (p = 0.047); 'subplacental hypervascularity' OR 10.8 95% CI (1.2-98.0) (p = 0.035); 'tortuous vascularity with 'chaotic branching' OR 10.8 95%CI (1.2-98.0) (p = 0.035); 'numerous coherent vessels involving the serosa-bladder interface OR 14.6 95% CI (2.7-80.5) (p = 0.002); and 'presence of bridging vessels OR 2.9 95% CI (1.4-6.9) (p = 0.005). Only the presence of numerous coherent vessels involving the bladder-serosal interface (p = 0.002) was proven to be independent predictor of major hemorrhage during hysterectomy. CONCLUSION: The use of 2D color Doppler and 3D power Doppler can help predict massive hemorrhage in cases of PAS disorders.

Prognosticators of intravoxel incoherent motion (IVIM) MRI for adverse maternal and neonatal clinical outcomes in patients with placenta accreta spectrum disorders.

BACKGROUND: The incidence of placenta accreta spectrum (PAS) disorders has increased rapidly in recent years and is associated with several maternal and neonatal complications. Intravoxel incoherent motion (IVIM) imaging is a method which can assess placental perfusion quantitatively. Therefore, the first aim of this study was to investigate whether patients with adverse maternal and neonatal outcomes of PAS disorders differed in the parameters from IVIM. A second aim was to identify these parameters for adverse peripartum outcome in gravid patients at risk for PAS. METHODS: The subject group consisted of patients with placenta previa, in which 75 patients had PAS disorders and 24 patients did not have PAS disorders between 28+0 and 39+6 weeks, respectively. All women underwent magnetic resonance imaging (MRI) examination including an IVIM sequence with 8 b values on a 1.5T scanner. The perfusion fraction (f), pseudodiffusion coefficient (D*), and standard diffusion coefficient (D) were calculated. All medical records were received postpartum. The final degree of placental invasion was established either by placental villi alterations from a placental sample or from maternity records of the women's general practitioners. RESULTS: Women with PAS disorders had a higher perfusion fraction (34.12%) than women without the disease (29.39%) (P<0.05). The perfusion fraction was 36.86% in women with massive blood loss and was 35.15% in women requiring transfusion, which was higher than women without massive blood loss and not requiring transfusion (P<0.05). The D value was 1.65×10-3 mm2/s in women with low birth weight, which was lower than that in women with appropriate birth weight (1.70×10-3 mm2/s) (P<0.05). CONCLUSIONS: Patients with PAS disorders differed in placental perfusion fraction from women without PAS disorders. The f and D value may be used to recognize patients with certain adverse clinical outcomes.

Modified cesarean hysterectomy technique for management of cases of placenta increta and percreta at a tertiary referral hospital in Egypt.

PURPOSE: To evaluate the effect of a modified type II radical hysterectomy on maternal morbidities and mortality in cases with abnormally invasive placenta (AIP). METHODS: 63 cases with AIP were managed at one of the largest referral centers in Egypt in a prospective study design. This technique entails devascularization of the uterus laterally on both sides and to clamp the uterus at the lowest possible point just below the level of the placenta while sparing the ureters. RESULTS: The difference between pre- and post-operative hemoglobin was only about 1 gm/dl, and the mean blood loss was 1673 ± 958 ml. There was a significant drop in the post-operative need for blood and blood product replacement, packed red blood cells (p = 0.013), fresh red blood cells (p < 0.001), and plasma units (p = 0.012). Operative time (skin to skin) averaged 190 ± 58.2 min as the technique is slow and utilizes meticulous hemostatic steps. ICU admission was 4.8% with a mean total hospital stay of 8.6 ± 3.6 days. Histopathological examination revealed 58 cases of placenta increta and five percreta cases. We also had 16 bladder injuries (25.4%) and two ureteric injuries, and no maternal mortalities. CONCLUSION: This technique reduces maternal morbidity and mortality while performing cesarean hysterectomy for cases with AIP.

Can introvoxel incoherent motion MRI be used to differentiate patients with placenta accreta spectrum disorders?

BACKGROUND: The incidence of PAS disorders increased rapidly in recent years, and introvoxel incoherent motion (IVIM) MRI has been applied in the assessment of placenta. The study aims to investigate whether the parameters from IVIM can be used to differentiate patients with PAS disorders complicating placenta previa and secondly to differentiate different categories of PAS disorders. METHODS: The study participants were comprised of 99 patients with placenta previa, including 16 patients with placenta accreta, 51 patients with increta, 8 patients with percreta and 24 patients without PAS disorders between 28 + 0 and 39 + 6 weeks. IVIM MRI was performed on a 1.5 T scanner. Perfusion fraction (f), pseudodiffusion coefficient (D*) and diffusion coefficient (D) were calculated. RESULTS: Women with PAS disorders had a higher perfusion fraction (p = 0.019) than women without the disease. Multiple comparisons showed perfusion fraction in patients without PAS disorders was significantly lower than in patients with placenta accreta and percreta(P = 0.018 and 0.033 respectively), but was not lower than in patients with increta(p = 1). CONCLUSION: Patients with placenta accreta and percreta differed in placental perfusion fraction from women with increta and without PAS disorders.