Sonographic findings of placental lacunae and the prediction of adherent placenta in women with placenta previa totalis and prior Cesarean section

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Placenta accreta spectrum in early and late pregnancy from an imaging perspective. A scoping review

Placenta accreta spectrum (PAS) disorders (with increasing order of the depth of invasion: accreta, increta, percreta) are quite challenging for the purpose of diagnosis and treatment. Pathological examination or imaging evaluation are not very dependable when considered as stand-alone diagnostic tools. On the other hand, timely diagnosis is of great importance, as maternal and fetal mortality drastically increases if patient goes through the third phase of delivery in a not well-suited facility. A multidisciplinary approach for diagnosis (incorporating clinical, imaging, and pathological evaluation) is mandatory, particularly in complicated cases. For imaging evaluation, the diagnostic modality of choice in most scenarios is ultrasound (US) exam; patients are referred for MRI when US is equivocal, inconclusive, or not visualizing placenta properly. Herewith, we review the reported US and MRI features of PAS disorders (mainly focusing on MRI), going over the normal placental imaging and imaging pitfalls in each section, and lastly, covering the imaging findings of PAS disorders in the first trimester and cesarean section pregnancy (CSP).

Prediction of placenta accreta spectrum in patients with placenta previa using a clinical, US and MRI combined model: A retrospective study with external validation

PURPOSE

To build and validate a predictive model of placental accreta spectrum (PAS) in patients with placenta previa (PP) combining clinical risk factors (CRF) with US and MRI signs.

METHOD

Our retrospective study included patients with PP from two institutions. All patients underwent US and MRI examinations for suspicion of PAS. CRF consisting of maternal age, cesarean section number, smoking and hypertension were retrieved. US and MRI signs suggestive of PAS were evaluated. Logistic regression analysis was performed to identify CRF and/or US and MRI signs associated with PAS considering histology as the reference standard. A nomogram was created using significant CRF and imaging signs at multivariate analysis, and its diagnostic accuracy was measured using the area under the binomial ROC curve (AUC), and the cut-off point was determined by Youden's J statistic.

RESULTS

A total of 171 patients were enrolled from two institutions. Independent predictors of PAS included in the nomogram were: 1) smoking and number of previous CS among CRF; 2) loss of the retroplacental clear space at US; 3) intraplacental dark bands, focal interruption of the myometrial border and placental bulging at MRI. A PAS-prediction nomogram was built including these parameters and an optimal cut-off of 14.5 points was identified, showing the highest sensitivity (91%) and specificity (88%) with an AUC value of 0.95 (AUC of 0.80 in the external validation cohort).

CONCLUSION

A nomogram-based model combining CRF with US and MRI signs might help to predict PAS in PP patients, with MRI contributing more than US as imaging evaluation.

Enhancing postpartum hemorrhage prediction in pernicious placenta previa: a comparative study of magnetic resonance imaging and ultrasound nomogram

Objective: To explore the risk factors of postpartum hemorrhage (PPH) in patients with pernicious placenta previa (PPP) and to develop and validate a clinical and imaging-based predictive model. Methods: A retrospective analysis was conducted on patients diagnosed surgically and pathologically with PPP between January 2018 and June 2022. All patients underwent PPP magnetic resonance imaging (MRI) and ultrasound scoring in the second trimester and before delivery, and were categorized into two groups according to PPH occurrence. The total imaging score and sub-item prediction models of the MRI risk score/ultrasound score were used to construct Models A and B/Models C and D. Models E and F were the total scores of the MRI combined with the ultrasound risk and sub-item prediction model scores. Model G was based on the subscores of MRI and ultrasound with the introduction of clinical data. Univariate logistic regression analysis and the logical least absolute shrinkage and selection operator (LASSO) model were used to construct models. The receiver operating characteristic curve andision curve analysis (DCA) were drawn, and the model with the strongest predictive ability and the best clinical effect was selected to construct a nomogram. Internal sampling was used to verify the prediction model's consistency. Results: 158 patients were included and the predictive power and clinical benefit of Models B and D were better than those of Models A and C. The results of the area under the curve of Models B, D, E, F, and G showed that Model G was the best, which could reach 0.93. Compared with Model F, age, vaginal hemorrhage during pregnancy, and amniotic fluid volume were independent risk factors for PPH in patients with PPP (p < 0.05). We plotted the DCA of Models B, D, E, F, and G, which showed that Model G had better clinical benefits and that the slope of the calibration curve of Model G was approximately 45°. Conclusion: LASSO regression nomogram based on clinical risk factors and multiple conventional ultrasound plus MRI signs has a certain guiding significance for the personalized prediction of PPH in patients with PPP before delivery.

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.

Comparison of T2-weighted and diffusion-weighted imaging for the diagnosis of placenta accreta spectrum abnormality

Background

Diffusion-weighted imaging (DWI) is feasible in prenatal imaging, and it exhibits better contrast between the placenta and the myometrium compared to T2-weighted (T2W) images.

Purpose

To compare magnetic resonance imaging (MRI) features of placenta accreta on T2W and DW imaging.

Material and Methods

In this retrospective study, 42 pregnant patients who underwent prenatal MRI were included. MRI was performed on a Siemens 1.5-T scanner. T2W and DWI sequences in the axial, sagittal, and/or coronal planes were compiled for review. Two radiologists independently interpreted T2W and DW images for placenta accreta. T2W and DWI scores were calculated based on the presence of features and graded as low, intermediate, and high risk. The association between imaging features and placental invasion on pathology was calculated using chi-square tests. Sensitivity, specificity, and positive and negative predictive values (NPV) were compared between T2W and DWI interpretations. Inter-reader agreement between the two radiologists for T2W and DWI scores was calculated using Cohen's kappa coefficient.

Results

Out of 42 pregnant patients, 10 were pathologically/surgically proven to have placenta accreta. There were no significant differences between T2W and DWI interpretations. Considering a cutoff >6 as positive, the T2W score had higher sensitivity (90% vs. 80%) and NPV (96.9% vs. 94.1%) than the DWI score. The specificity and positive predictive value were 100% for both scores. The inter-reader agreement of T2W score was higher (k = 0.943 vs. 0.882).

Conclusion

T2W and DWI are comparable in diagnosing placenta accreta spectrum. T2W sequences have higher sensitivity, NPV, and inter-reader agreement than DWI.

Bleeding-related outcomes of low-risk total placenta previa are equivalent to those of partial/marginal placenta previa

OBJECTIVE

To clarify whether "low-risk total PP" patients bleed more than partial/marginal PP patients.

MATERIALS AND METHODS

The retrospective cohort study was performed involving patients with PP between April 2006 and December 2018. The placental position was determined by ultrasound. From medical charts, the backgrounds as well as obstetric and neonatal outcomes of PP patients were retrieved.

RESULTS

This study included 349 patients with PP, which was classified into three types according to the distance between the placenta and internal ostium: total (n = 174), partial (n = 52), and marginal (n = 123) PP. In total PP patients, three factors (prior CS, anterior placenta, and placental lacunae on ultrasound) significantly increased blood loss at CS, the need for hysterectomy, homologous transfusion (≥10 U), and ICU admission. No significant difference was observed in bleeding-related poor outcomes (rate of blood loss ≥2000 mL, amount of homologous transfusion, need for hysterectomy, and ICU admission) between total PP patients without all three factors: "low-risk total PP patients" and partial/marginal PP patients (19.8 vs. 17.1%; p = 0.604, 3.7 vs. 1.1%; p = 0.330, 1.2 vs. 1.1%; p = 1.000, and 1.2 vs. 1.1%; p = 1.000, respectively).

CONCLUSION

Prior CS, anterior placenta, and placental lacunae on ultrasound were risk factors for a bleeding-related poor outcome in total PP patients. Total PP patients without these three factors showed the same bleeding-related poor outcome as partial/marginal PP patients.

A Penance to Misdeed: A Case Report About Placenta Percreta

Placenta percreta is a condition in which the placenta penetrates through the myometrium and into the uterine serosa. Sometimes it can be complicated by attachment to the surrounding structures or organs. The incidence of this condition is on the rise because of increased rates of cesarean sections. A 29-year-old gravida two, para one, living one with a previous cesarean section at 39 weeks of gestation was referred from a primary health center with complaints of leaking per vaginum for ten hours. She had no other associated symptoms. Her antenatal period was uneventful with all routine investigations within normal limits. A growth scan was done at 34 weeks of gestation. The scan was corresponding to the period of gestation with adequate liquor and placenta at fundoposterior location. A decision was taken to perform an emergency cesarean section in view of the previous cesarean section with premature rupture of membranes (PROM) and poor bishop score. After delivery of the baby when the placenta was tried to be removed, it could not be removed even with gentle traction. No plane of cleavage was identified between the uterine wall and placenta. The uterus was exteriorized and the placenta was found to have firmly adhered to the uterine wall and serosa on the fundal region. An intraoperative diagnosis of morbidly adherent placenta was made. A decision to perform an emergency obstetric hysterectomy was taken. A subtotal hysterectomy was done after counseling and necessary informed consent. Histopathology of the specimen was consistent with the findings of placenta percreta.

Analysis of risk factors for massive intraoperative bleeding in patients with placenta accreta spectrum

BACKGROUND

To analyze relevant factors for massive postpartum hemorrhage in women with placenta accreta spectrum in order to improve the ability to identify those at risk for intraoperative bleeding and improve outcome.

METHODS

This study is a retrospective study and based on data from Hospital electronic medical record. Placenta accreta patients who delivered by cesarean section at Peking University Third Hospital from September 2017 to December 2019 were selected and included. According to the amount of intraoperative bleeding, they were categoried into the massive bleeding group (bleeding volume ≥ 2000 mL, 68 cases) and non-massive bleeding group (bleeding volume < 2000 mL, 99 cases). Univariate analysis and multivariate logistic regression were used to analyze the correlations between related risk factors or ultrasound imaging characteristics and the severity of bleeding during operation.

RESULTS

(1) There were statistically significant differences in gravidity, parity, number of prior cesarean deliveries and placenta accreta ultrasound scores (P < 0.05) between the two groups of patients. (2) Among the ultrasonographic indicators, the disappearance of the post-placental clear space, the emergence of cross-border blood vessels in the region of subplacental vascularity, interruption or disappearance of the bladder line, and the presence of the cervical blood sinus had the most significant correlation with hemorrhage during PAS (P < 0.05).

CONCLUSION

The presence of cervical blood sinus, interruption or disappearance of bladder line, the disappearance of the post-placental clear space and abnormal subplacental vascularity are independent risk factors for massive hemorrhage during PAS. We should pay more attention to these indicators in prenatal ultrasound examination in order to reduce the intraoperative bleeding and improve maternal outcomes.

Ultrasound as a Sole Modality for Prenatal Diagnosis of Placenta Accreta Spectrum: Potentialities and Pitfalls

Background  Placenta accreta spectrum (PAS) is a significant cause of maternal and neonatal mortality and morbidity. Its prevalence has been rising considerably, primarily due to the increasing rate of primary and repeat cesarean sections. Accurate prenatal identification of PAS allows optimal management because the timing of delivery, availability of blood products, and recruitment of skilled anesthesia, and surgical team can be arranged in advance.

Aims and Objectives  This study aimed to (1) study the ultrasound and color Doppler features of PAS, (2) correlate imaging findings with clinical and per-operative/histopathological findings, and (3) evaluate the accuracy of ultrasound for the diagnosis of PAS in patients with previous cesarean section.

Materials and Methods  This prospective study was conducted in radiology department of a tertiary care hospital. After screening 1,200 pregnant patients, 50 patients of placenta previa with period of gestation ≥ 24 weeks and history of at least one prior cesarean section were included in the study. Following imaging features were evaluated: (1) gray scale covering intraplacental lacunae, disruption of uterovesical interface, myometrial thinning, loss of retroplacental clear space, and focal exophytic masses; and (2) color Doppler covering intraplacental lacunar flow, hypervascularity of uterine serosa–bladder wall interface, and perpendicular bridging vessels between placenta and myometrium.

Study Design  Present study is a prospective one in a tertiary care hospital.

Results  Of the 19 PAS cases, 18 were correctly diagnosed on ultrasonography (USG) and confirmed either by histopathological analysis of hysterectomy specimen or per-operatively due to difficulty in placental removal. PAS was correctly ruled out in 27 of 31 patients. The diagnostic accuracy of USG was 90%. The sensitivity, specificity, positive, and negative predictive values were 94.7, 87.1, 81.8, and 96.4%, respectively.

Conclusion  Ultrasound is indispensable for the evaluation of pregnant patients. It is an important tool for diagnosing PAS, thereby making the operating team more cautious and better equipped for difficult surgery and critical postoperative care. It can be relied upon as the sole modality to accurately rule out PAS in negative patients, thereby obviating unnecessary psychological stress among patients due to possible hysterectomy.

Prediction of placenta accreta spectrum in patients with placenta previa using clinical risk factors, ultrasound and magnetic resonance imaging findings

OBJECTIVES

To predict placental accreta spectrum (PAS) in patients with placenta previa (PP) evaluating clinical risk factors (CRF), ultrasound (US) and magnetic resonance imaging (MRI) findings.

METHODS

Seventy patients with PP were retrospectively selected. CRF were retrieved from medical records. US and MRI images were evaluated to detect imaging signs suggestive of PAS. Univariable analysis was performed to identify CRF, US and MRI signs associated with PAS considering histology as standard of reference. Receiver operating characteristic curve (ROC) analysis was performed, and the area under the curve (AUC) was calculated. Multivariable analysis was also performed.

RESULTS

At univariable analysis, the number of previous cesarean section, smoking, loss of the retroplacental clear space, myometrial thinning < 1 mm, placental lacunae, intraplacental dark bands (IDB), focal interruption of myometrial border (FIMB) and abnormal vascularity were statistically significant. The AUC in predicting PAS progressively increased using CRF, US and MRI signs (0.69, 0.79 and 0.94, respectively; p < 0.05); the accuracy of MRI alone was similar to that obtained combining CRF, US and MRI variables (AUC = 0.97) and was significantly higher (p < 0.05) than that combining CRF and US (AUC = 0.83). Multivariable analysis showed that only IDB (p = 0.012) and FIMB (p = 0.029) were independently associated with PAS.

CONCLUSIONS

MRI is the best modality to predict PAS in patients with PP independently from CRF and/or US finding. It is reasonable to propose the combined assessment of CRF and US as the first diagnostic level to predict PAS, sparing MRI for selected cases in which US findings are uncertain for PAS.

An Ultrasound Scoring Model for the Prediction of Intrapartum Morbidly Adherent Placenta and Maternal Morbidity: A Cross-Sectional Study

OBJECTIVE

 To design an ultrasound scoring model for the prediction of the intrapartum morbidly adherent placenta (MAP) and maternal morbidity.

PATIENTS AND METHODS

 114 females with singleton pregnancies ≥ 28 weeks of gestation referred for suspicion of MAP were included. All patients underwent examination by two-dimensional ultrasound with the color Doppler setting. Five signs were evaluated: the retroplacental echolucent space, placental lacunae, the hyperechoic uterine-bladder interface, retroplacental myometrium thickness, and subplacental, uterine serosa-bladder wall, intraplacental and bladder wall vascularity. We designed a score ranging from 0-8.5 points, including the five signs according to their odds ratios and evaluated its prediction for MAP and maternal morbidity.

RESULTS

 Using multivariate logistic regression, all ultrasound signs were significant dependent predictors for both MAP and maternal morbidity (myometrium thickness < 1 mm followed by lacunae ≥ 4 and lost retroplacental echolucent space). The only independent predictors for MAP were myometrium thickness < 1 mm and lacunae ≥ 4, while myometrium thickness < 1 mm and lost retroplacental echolucent space were predictive for maternal morbidity. The score showed a perfect agreement with MAP and a good one for maternal morbidity.

CONCLUSION

 Application of the score we designed can improve the ultrasound diagnosis of MAP and the maternal outcome.

Placenta previa with posterior extrauterine adhesion: clinical features and management practice

Background

A diagnostic sign on magnetic resonance imaging, suggestive of posterior extrauterine adhesion (PEUA), was identified in patients with placenta previa. However, the clinical features or surgical outcomes of patients with placenta previa and PEUA are unclear. Our study aimed to investigate the clinical characteristics of placenta previa with PEUA and determine whether an altered management strategy improved surgical outcomes.

Methods

This single institution retrospective study examined patients with placenta previa who underwent cesarean delivery between 2014 and 2019. In June 2017, we recognized that PEUA was associated with increased intraoperative bleeding; thus, we altered the management of patients with placenta previa and PEUA. To assess the relationship between changes in practice and surgical outcomes, a quasi-experimental method was used to examine the difference-in-difference before (pre group) and after (post group) the changes. Surgical management was modified as follows: (i) minimization of uterine exteriorization and adhesion detachment during cesarean delivery and (ii) use of Nelaton catheters for guiding cervical passage during Bakri balloon insertion. To account for patient characteristics, propensity score matching and multivariate regression analyses were performed.

Results

The study cohort (n = 141) comprised of 24 patients with placenta previa and PEUA (PEUA group) and 117 non-PEUA patients (control group). The PEUA patients were further categorized into the pre (n = 12) and post groups (n = 12) based on the changes in surgical management. Total placenta previa and posterior placentas were more likely in the PEUA group than in the control group (66.7% versus 42.7% [P = 0.04] and 95.8% versus 63.2% [P < 0.01], respectively). After propensity score matching (n = 72), intraoperative blood loss was significantly higher in the PEUA group (n = 24) than in the control group (n = 48) (1515 mL versus 870 mL, P < 0.01). Multivariate regression analysis revealed that PEUA was a significant risk factor for intraoperative bleeding before changes were implemented in practice (t = 2.46, P = 0.02). Intraoperative blood loss in the post group was successfully reduced, as opposed to in the pre group (1180 mL versus 1827 mL, P = 0.04).

Conclusions

PEUA was associated with total placenta previa, posterior placenta, and increased intraoperative bleeding in patients with placenta previa. Our altered management could reduce the intraoperative blood loss.

Special Report of the Society for Maternal-Fetal Medicine Placenta Accreta Spectrum Ultrasound Marker Task Force: Consensus on definition of markers and approach to the ultrasound examination in pregnancies at risk for placenta accreta spectrum

Placenta accreta spectrum includes the full range of abnormal placental attachment to the uterus or other structures, encompassing placenta accreta, placenta increta, placenta percreta, morbidly adherent placenta, and invasive placentation. The incidence of placenta accreta spectrum has increased in recent years, largely driven by increasing rates of cesarean delivery. Prenatal detection of placenta accreta spectrum is primarily made by ultrasound and is important to reduce maternal morbidity associated with the condition. Despite a large body of research on various placenta accreta spectrum ultrasound markers and their screening performance, inconsistencies in the literature persist. In response to the need for standardizing the definitions of placenta accreta spectrum markers and the approach to the ultrasound examination, the Society for Maternal-Fetal Medicine convened a task force with representatives from the American Institute of Ultrasound in Medicine, the American College of Obstetricians and Gynecologists, the American College of Radiology, the International Society of Ultrasound in Obstetrics and Gynecology, the Society for Radiologists in Ultrasound, the American Registry for Diagnostic Medical Sonography, and the Gottesfeld-Hohler Memorial Ultrasound Foundation. The goals of the task force were to assess placenta accreta spectrum sonographic markers on the basis of available data and expert consensus, provide a standardized approach to the prenatal ultrasound evaluation of the uterus and placenta in pregnancies at risk of placenta accreta spectrum, and identify research gaps in the field. This manuscript provides information on the Placenta Accreta Spectrum Task Force process and findings.

Ultrasonographic Diagnosis of Placenta Accreta Spectrum (PAS) Disorder: Ideation of an Ultrasonographic Score and Correlation with Surgical and Neonatal Outcomes

The objective of this study was to evaluate a novel ultrasonographic scoring system for the diagnosis of PAS and the prediction of maternal and neonatal outcomes. In this retrospective study, 138 patients with at least one previous caesarean section (CS) and placenta previa were included. They were divided into four groups ranging from Group 0 (Non PAS) to Group 3 (Placenta Percreta) according to the histological or surgical confirmation. Their ultrasound examinations during pregnancy were reviewed according to the nine different ultrasound signs reported by the European Working Group on Abnormally Invasive Placenta. For each parameter, 0 to 2 points were assigned. The sum of the points reflects the severity of PAS with a maximum score of 20. The scoring system revealed good performances in evaluation metrics, with an overall accuracy of 94%. In addition to this, patients’ characteristics and surgical and neonatal outcomes were analyzed with an evidence of higher incidence of complications in severe forms. Our study suggests that antenatal ultrasonographic diagnosis of PAS is feasible with sufficient level of accuracy. This will be important in identifying high-risk patients and implementing preventive strategy.

Functional diagnosis of placenta accreta by intravoxel incoherent motion model diffusion-weighted imaging

OBJECTIVES

To investigate the diagnostic value of intravoxel incoherent motion (IVIM) DWI for placenta accreta by comparing diffusion and perfusion characteristics of placentas with accreta lesions (APs) with those of normal placentas (NPs).

METHODS

Twenty-five pregnant women with AP and 24 with NP underwent 3-T magnetic resonance examinations with IVIM-DWI. The perfusion percentage (f), pseudo-diffusion coefficient (D*), and diffusion coefficient (D) values were calculated from different ROIs: the entire-plane of the AP (AP-ROI) and NP (NP-ROI) and the implanted (IR-ROI) and non-implanted region (NIR-ROI) of the AP. The AP-ROIs and NP-ROIs were compared using covariance analysis; the IR-ROIs and NIR-ROIs were compared using the Wilcoxon signed-rank test. ROC curves were produced to evaluate the parameters for predicting placenta accreta.

RESULTS

The f and D* values for the AP-ROIs ([45.0 ± 7.63]%, [11.64 ± 2.15]mm²/s) were significantly higher than those for the NP-ROIs ([31.85 ± 5.96]%, [9.04 ± 3.13]mm²/s) (both p < 0.05); the IR-ROIs (54.8%, 14.03 mm²/s) were also significantly higher than the NIR-ROIs (37.4%, 11.4 mm²/s) (both p < 0.05). No significant differences were found between the D values of the AP-ROIs and NP-ROIs (p > 0.05) or of the IR-ROIs and NIR-ROIs (p > 0.05). The areas under the curve for f and D* of the ROC curves were 0.93 and 0.79, respectively.

CONCLUSIONS

These results suggest that the IVIM parameters f and D* can be used to quantitatively evaluate the higher perfusion of AP when compared with NP. Furthermore, IVIM may be a useful functional diagnostic technique to predict placenta accreta.

KEY POINTS

• Intravoxel incoherent motion (IVIM) may be a useful diagnostic technique to quantitatively estimate the perfusion of the placenta. • The perfusion percentage (f) and pseudo-diffusion coefficient (D*) values differed significantly between placentas with accreta lesions and normal placentas. • ROC curves showed that perfusion percentage (f) and pseudo-diffusion coefficient (D*) values could accurately predict placenta accreta.

Missing decidual Doppler signals as a new diagnostic criterion for placenta accreta spectrum: A case described using superb microvascular imaging

We present a case of a 34-year-old pregnant woman with a prior cesarean delivery presenting with placenta previa. Placenta previa accreta was diagnosed from missing decidual flow signals using superb microvascular imaging (SMI). At 31 weeks' gestation, B-mode ultrasonography showed that the placenta was attached to the anterior uterine segment, extending over the internal cervical os. In normally appearing myometrium, SMI demonstrated double layers of flow signals underneath the placental basal plate, corresponding to myometrial and decidual flows. The thin myometrium located on the bladder where sonolucent zones were not visible revealed three different flow patterns in the Doppler signals underneath the basal plate as follows: double layers (both myometrium and decidual tissues present); a single layer (myometrium alone) or no layers (decidual tissues missing). A cesarean hysterectomy was performed at 37 weeks, and histology confirmed the presence of placenta accreta.

Structured evaluation and reporting in imaging of placenta and umbilical cord

The human placenta plays a pivotal role in development and growth of the fetus. Disorder of this multifunctional organ is central to various fetal disorders. Doppler sonography and MRI provide excellent diagnostic evaluation of the placental morphology and umbilical cord. Decades of experience in obstetric imaging have highlighted the need of careful prenatal assessment of placenta. However, in most of the routine obstetric scans, the evaluation and reporting of the placental examination is limited to the location and grade of the placenta. The purpose of this article is to review the existing literature and facilitate step-by-step evaluation of the placenta and umbilical cord by the radiologists.

Uterine body placenta accreta spectrum: A detailed literature review

Placenta accreta spectrum (PAS) is a major obstetrical problem whose incidence is rising. Current guidelines recommend screening of all women with placenta previa and risk factors for PAS between 20 and 24 weeks. Risk factors, diagnosis, and management of previa PAS are well established, but an apparently normal location of the placenta does not exclude PAS. Literature data are scarce on uterine body PAS, which carries a high risk of maternal and neonatal adverse outcome, but is still easily missed on prenatal ultrasound. We conducted a comprehensive review to identify possible risk factors, clinical presentations, and diagnostic modalities of uterine PAS. A total of 133 cases were found during a 70-year period (1949-2019). The vast majority of them presented with signs of uterine rupture, even prior to the viability threshold of 24 weeks (up to 45%). Major risk factors included previous cesarean delivery, uterine curettage, uterine surgery, Asherman's syndrome, manual removal of the placenta, endometritis, high parity, young maternal age, in vitro fertilization, radiotherapy, uterine artery embolization, and uterine leiomyoma. Diagnosis was pre-symptomatic in only 3% of cases. Future studies should differentiate between previa PAS and uterine body PAS.

Prediction Model for Massive Transfusion in Placenta Previa during Cesarean Section

PURPOSE

Recently, obstetric massive transfusion protocols have shifted toward early intervention. This study aimed to develop a prediction model for transfusion of ≥5 units of packed red blood cells (PRBCs) during cesarean section in women with placenta previa.

MATERIALS AND METHODS

We conducted a cohort study including 287 women with placenta previa who delivered between September 2011 and April 2018. Univariate and multivariate logistic regression analyses were used to test the association between clinical factors, ultrasound factors, and massive transfusion. For the external validation set, we obtained data (n=50) from another hospital.

RESULTS

We formulated a scoring model for predicting transfusion of ≥5 units of PRBCs, including maternal age, degree of previa, grade of lacunae, presence of a hypoechoic layer, and anterior placentation. For example, total score of 223/260 had a probability of 0.7 for massive transfusion. Hosmer-Lemeshow goodness-of-fit test indicated that the model was suitable (p>0.05). The area under the receiver operating characteristics curve (AUC) was 0.922 [95% confidence interval (CI) 0.89-0.95]. In external validation, the discrimination was good, with an AUC value of 0.833 (95% CI 0.70-0.92) for this model. Nomogram calibration plots indicated good agreement between the predicted and observed outcomes, exhibiting close approximation between the predicted and observed probability.

CONCLUSION

We constructed a scoring model for predicting massive transfusion during cesarean section in women with placenta previa. This model may help in determining the need to prepare an appropriate amount of blood products and the optimal timing of blood transfusion.

Value of ultrasound scoring system for assessing risk of pernicious placenta previa with accreta spectrum disorders and poor pregnancy outcomes

PURPOSE

To evaluate a system for assessing the risk of pernicious placenta previa (PPP) with placenta accreta spectrum (PAS) disorders and poor pregnancy outcomes.

METHODS

This prospective study focused on PPP women at ≥ 28 weeks' pregnancy. Transabdominal or transvaginal ultrasonography was used to assess PAS and poor pregnancy outcomes with a system involving uteroplacental demarcation, number and size of lacunae, bladder line, and placental basal and lacunae flow. Every item was assigned 0-2 points, and the sum yielded the final score. Diagnosis of PAS was based on surgery or pathology. One or more of postpartum hemorrhage (PPH) ≥ 1000 ml, hysterectomy, and organ invasion were regarded as a poor pregnancy outcome. Receiver operating characteristic (ROC) curves were generated.

RESULTS

Fifty-one PPP women were included, with 70.6% having PAS and 75.0% of PAS women having a poor pregnancy outcome. The incidence of PAS diagnosis was 36.4% for those with a score < 5 points, with 0% having a poor outcome; 76.5% for those with a score ≥ 5 to < 8 points, with 61.5% having a poor outcome; and 100% for those with a score ≥ 8 points, with 100% having a poor pregnancy outcome.

CONCLUSION

The system for predicting PPP with PAS and poor pregnancy outcomes was of high accuracy.

Placenta accreta in the department of gynaecology and obstetrics in Rabat, Morocco: case series and review of the literature

Placenta accreta spectrum disorders is a rare pathology but the incidence has not stopped to increase in recent years. The purpose of our work was the analysis of the epidemiological profile of our patients, the circumstances of diagnosis, the interest of paraclinical explorations in antenatal diagnosis and the evaluation of the evolutionary profile. We hereby report a case series spread over a period of one year from 01/01/2015 to 01/01/2016 at the Gynaecology-Obstetrics department of the University Hospital Center IBN SINA of Rabat where we identified six cases of placenta accreta. We selected patients whose diagnosis was confirmed clinically and histologically. The major risk factors identified were a history of placenta previa, previous caesarean section, advanced maternal age, multiparity. 2D ultrasound and magnetic resonance imaging (MRI) allowed us to strongly suspect the presence of a placenta accreta in a pregnant woman with risk factor(s) but the diagnosis of certainty was always histological. Placenta accreta spectrum disorders were associated with a high risk of severe postpartum hemorrhage, serious comorbidities, and maternal death. Leaving the placenta in situ was an option for women who desire to preserve their fertility and agree to continuous long-term monitoring in centers with adequate expertise but a primary elective caesarean hysterectomy was the safest and most practical option. Placenta accreta spectrum disorders is an uncommon pathology that must be systematically sought in a parturient with risk factors, to avoid serious complications. In light of the latest International Federation of Gynecology and Obstetrics (FIGO) recommendations of 2018, a review of the literature and finally the experience of our center, we propose a course of action according to whether the diagnosis of the placenta is antenatal or perpartum.

New three-dimensional/four-dimensional volume rendering imaging software for detecting the abnormally invasive placenta

OBJECTIVE

This study aimed to determine the role of three-dimensional (3D)/four-dimensional (4D) volume rendering ultrasound (VRU) in the diagnosis of abnormally invasive placenta (AIP).

MATERIALS AND METHODS

Twelve consecutive patients strongly suspected of having AIP on the basis of conventional ultrasound (US) and clinical history performed between September 2016 and December 2016 in the main tertiary referral hospital in Surabaya, East Java were included in this prospective observational study. A Samsung WS 80A Elite US scanner with a 3D/4D "crystal vue" and "realistic vue" volume rendering mode was used to establish the diagnosis of AIP and evaluate the site, and depth of placental invasion. The VRU images were compared with the intraoperative findings.

RESULTS

Using this novel US technique, all cases of suspected AIP were subsequently confirmed during surgery. Importantly, the new US technique provided a correct diagnosis of the degree of invasion in 11 out of these 12 suspected AIP cases: 5/5 for placenta percreta, 3/3 for placenta increta, and 2/3 for placenta accreta; one patient was misdiagnosed in terms of the degree of placenta accreta, and one patient had normal implantation).

CONCLUSION

This new software of 3D/4D VRU represents a promising technique for the preoperative diagnosis and staging of AIP.

Development of a scoring system for prediction of placenta accreta and determine the accuracy of its results

Background: Optimal management of women with placenta accreta requires accurate preoperative diagnosis. Therefore, this study was conducted with the aim to evaluate a new prediction scoring items for risk assessment on placenta accreta and determine its accuracy ratio.Methods: This prospective cohort study was carried out on 159 suspected pregnant women morbidly adherent placenta (MAP) in Shariati, Imam Khomeini, and Yas Hospitals in Tehran from October 2016 to May 2018. The number of previous cesarean deliveries; lacunae stage, location of placenta; Doppler assessment; and loss of clear zone were used for review and scoring of ultrasound images. Ultimately after collecting scores, subjects fall into one of the following three categories: low (≤5 points), moderate (6-7 points), or high (8-10 points) probability for placenta accreta. Ultimately, diagnosis of accreta was based on hysterectomy during surgery or reports of pathology. A logistic regression model was used to calculate the probability of placenta accreta on univariable analysis, to assess the discriminant power of all explanatory variables assessed by the receiver operating characteristic (ROC) curve.Results: The area-under-the-ROC curve of the composite scores was 98% and the overall sensitivity, specificity, and positive and negative predictive values of our developed scoring system were 91.84%, 87.27%, 86.54%, and 92.31%, respectively.Conclusion: Combination of several simple ultrasound and clinical characteristics in a scoring system may be highly effective for prenatal risk assessment and prediction of placenta accreta. Output of scoring system helps medical staff to prepare appropriately before surgery and avoid perinatal mortality and morbidity.

Serum ischemia modified albumin level and its relationship with the thiol/disulfide balance in placenta percreta patients

The pathogenesis of placenta percreta (PP) is not very well known. This study was designed to analyse the oxidative stress (OS), the thiol/disulphide balance, and ischaemia-modified albumin (IMA) the women with PP. The study included 38 pregnant women with PP and 40 similarly aged healthy pregnant women in their third trimester of gestation. We measured the IMA, native and total thiols, and disulphide concentrations in the maternal sera of all of the participating women. The IMA levels were higher and the native and total thiols were lower in the PP group than in the control group. However, there was no statistical significance with respect to the thiol/disulphide balance between the two groups. The results of this study suggest that an increase in the ischaemia and OS and a decrease in the antioxidant status may contribute to the pathogenesis of PP. Impact statement What is already known on this subject? Placenta percreta (PP) is a serious complication of pregnancy. Although there are several studies investigating the pathophysiological mechanism of PP, whether the pathology results from a lack of decidua or from the over-invasiveness of trophoblasts remains controversial. The pathology of PP is poorly understood. What do the results of this study add? This prospective study has shown an increased ischaemia modified albumin (IMA) and a decreased antioxidant capacity in the patients with placenta percreta. The results from 38 women with PP suggest that the serum concentrations of IMA and the oxidative stress parameters may be able to predict PP in cases of uncertainty. What are the implications of these findings for clinical practice and/or further research? The implication of these findings shed light on understanding the pathogenesis of PP for further research.

Prediction of morbidly adherent placenta using a scoring system

OBJECTIVE

To evaluate the accuracy of an ultrasound-based scoring system for diagnosing morbidly adherent placenta (MAP).

METHODS

This study included pregnant women referred to our ultrasound unit during 2013-2015 because of suspected MAP on a previous ultrasound examination or because they had at least one previous Cesarean delivery. All women were assessed using a scoring system based on the following: number and size of placental lacunae; obliteration of the demarcation between the uterus and placenta; placental location; color Doppler signals within placental lacunae; hypervascularity of the placenta-bladder and/or uteroplacental interface zone; and number of previous Cesarean deliveries. Each criterion was assigned 0, 1 or 2 points and the sum of points yielded the final score. Patients were classified into low, moderate or high probability for MAP based on the final score. The presence of MAP was determined by the surgeon at delivery and clinical descriptions were documented in the electronic patient file. Pathological diagnoses were available only in cases that underwent hysterectomy.

RESULTS

In total, 258 pregnant women were included in the study, of whom 23 (8.9%) were diagnosed with MAP. There was a statistically significant difference in the prevalence of MAP when women were grouped according to the scoring system, with 0.9%, 29.4% and 84.2% in the low, moderate and high probability groups, respectively (P < 0.0001). All sonographic criteria of the scoring system were significantly associated with MAP (P < 0.0001). Receiver-operating characteristics (ROC) curves for prediction of MAP using the number of placental lacunae and obliteration of the uteroplacental demarcation yielded an area under the ROC curve of 0.94 (95% CI, 0.86-1.00).

CONCLUSIONS

Our proposed scoring system is highly predictive of MAP in patients at risk. This allows an adequate multidisciplinary team approach for the planning and timing of delivery in such cases. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Magnetic Resonance Imaging and Sonography in the Diagnosis of Placental Invasion

OBJECTIVES

To compare older and newer magnetic resonance imaging (MRI) criteria for placental invasion and to compare the sensitivity, specificity, and accuracy of MRI and sonography in determining the depth of placental invasion.

METHODS

Forty pregnant patients at high risk for morbidly adherent placenta based on prenatal sonography underwent MRI evaluations. Two reviewers, who were blinded to the original MRI and sonographic interpretations, clinical history, and obstetric/pathologic findings, reviewed the MRI examinations. The MRI and sonographic scans were analyzed for the presence and depth of invasion. The MRI scans were tabulated for the presence of dark intraplacental T2 bands, bulging of the myometrium, increased vascularity, and indistinct myometrium, loss of the dark T2 myometrial/placental interface, and a thin myometrium. The obstetric/pathologic results served as the reference standards.

RESULTS

Eighteen of 40 patients had a morbidly invasive placenta. The sensitivity, specificity, and accuracy of MRI and sonography were not significantly different. The accuracy rates for determining the depth of placental invasion by readers 1 and 2 were 0.65 and 0.55, respectively (P > .05). According to the Cohen κ statistic, there was a good inter-reader agreement between the MRI readers in assessing the depth of placental invasion (κ = 0.45). The features most commonly seen were dark T2 bands, bulging of the uterus, and loss of the dark T2 interface, which were all associated with the presence of placental invasion.

CONCLUSIONS

The diagnosis of placental invasion remains challenging on sonography and MRI, which perform similarly. The presence of 2 or more criteria adds specificity to the diagnosis of placental invasion on MRI.

Accuracy of ultrasound in antenatal diagnosis of placental attachment disorders

OBJECTIVES

To evaluate the accuracy of ultrasound in the diagnosis of placenta accreta and its variants, and to assess the impact of prenatal diagnosis in our population.

METHODS

A total of 314 women with placenta previa were enrolled prospectively and underwent transabdominal and transvaginal ultrasound examinations. An ultrasound diagnosis (grayscale and color/power Doppler) of placental attachment disorder (PAD) was based on the detection of at least two of the following ('two-criteria system'): loss/irregularity of the retroplacental clear zone, thinning/interruption of the uterine serosa-bladder wall interface, turbulent placental lacunae with high velocity flow, myometrial thickness < 1 mm, increased vascularity of the uterine serosa-bladder wall interface, loss of vascular arch parallel to the basal plate and/or irregular intraplacental vascularization. Definitive diagnosis was made at delivery by Cesarean section. Maternal outcome in cases diagnosed antenatally was compared with that in cases diagnosed at delivery.

RESULTS

There were 37/314 cases of PAD (29 anterior and eight posterior). The two-criteria system identified 30 cases of placenta accreta, providing a sensitivity of 81.1% and specificity of 98.9%. When anterior and posterior placentae were considered separately, the detection rates of PAD were 89.7 and 50.0%, respectIvely. Maternal outcome was better in women with prenatal diagnosis of PAD, as seen by less blood loss and shorter hospitalization.

CONCLUSIONS

Our data confirmed that grayscale and color Doppler ultrasound have good performance in the diagnosis of PAD and that prenatal diagnosis improves maternal outcome. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Utility of ultrasound and magnetic resonance imaging in prenatal diagnosis of placenta accreta: A prospective study

CONTEXT

Placenta accreta is the abnormal adherence of the placenta to the uterine wall and the most common cause for emergency postpartum hysterectomy. Accurate prenatal diagnosis of affected pregnancies allows optimal obstetric management.

AIMS

To summarize our experience in the antenatal diagnosis of placenta accreta on imaging in a tertiary care setup. To compare the accuracy of ultrasound (USG) with color Doppler (CDUS) and magnetic resonance imaging (MRI) in prenatal diagnosis of placenta accreta.

SETTINGS AND DESIGN

Prospective study in a tertiary care setup.

MATERIALS AND METHODS

A prospective study was conducted on pregnant females with high clinical risk of placenta accreta. Antenatal diagnosis was established based on CDUS and MRI. The imaging findings were compared with final diagnosis at the time of delivery and/or pathologic examination.

STATISTICAL ANALYSIS USED

The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for both CDUS and MRI. The sensitivity and specificity values of USG and MRI were compared by the McNemar test.

RESULTS

Thirty patients at risk of placenta accreta underwent both CDUS and MRI. Eight cases of placenta accreta were identified (3 vera, 4 increta, and 1 percreta). All patients had history of previous cesarean section. Placenta previa was present in seven out of eight patients. USG correctly identified the presence of placenta accreta in seven out of eight patients (87.5% sensitivity) and the absence of placenta accreta in 19 out of 22 patients (86.4% specificity). MRI correctly identified the presence of placenta accreta in 6 out of 8 patients (75.0% sensitivity) and absence of placenta accreta in 17 out of 22 patients (77.3% specificity). There were no statistical differences in sensitivity (P = 1.00) and specificity (P = 0.687) between USG and MRI.

CONCLUSIONS

Both USG and MRI have fairly good sensitivity for prenatal diagnosis of placenta accreta; however, specificity does not appear to be as good as reported in other studies. Both modalities have complimentary role and in cases of inconclusive findings with one imaging modality, the other modality may be useful for obtaining the diagnosis. CDUS remains the first primary modality for antenatal diagnosis of placenta accreta, with MRI reserved for cases where USG is inconclusive.

Placenta accreta: diagnosis, management and the molecular biology of the morbidly adherent placenta

Placenta accreta is now the chief cause of postpartum hemorrhage resulting in maternal and neonatal morbidity. Prenatal diagnosis decreases blood loss at delivery and intra and post-partum complications. Ultrasound is critical for diagnosis and MRI is a complementary tool when the diagnosis is uncertain. Peripartum hysterectomy has been the standard of therapy but conservative management is increasingly being used. The etiology of accreta is due to a deficiency of maternal decidua resulting in placental invasion into the uterine myometrium. The molecular basis for the development of invasive placentation is yet to be elucidated but may involve abnormal paracrine/autocrine signaling between the deficient maternal decidua and the trophoblastic tissue. The interaction of hormones such as Relaxin which is abundant in maternal decidua and insulin-like 4, an insulin-like peptide found in placental trophoblastic tissue may play role in the formation of placenta accreta.

Urological Manifestations of Placenta Percreta

Placenta percreta is a condition of pregnancy associated with abnormal decidua placenta. It is characterized by invasion of chorionic villi past the myometrium and serosa, towards urogenital organs. Complications include massive hemorrhage, bladder dysfunction, and severe infections during delivery. Reports suggest an increasing prevalence of this condition. From a urological perspective, this review suggests how early diagnostic modalities, effective treatment plans, and appropriate surgical methods may aid in decreasing the morbidity and mortality of placenta percreta. The importance of maintaining bladder integrity during hysterectomy is emphasized.

A novel sonographic scoring system for antenatal risk assessment of obstetric complications in suspected morbidly adherent placenta

OBJECTIVES

The purpose of this study was to evaluate a novel sonographic scoring system for risk assessment of complications in patients suspected of having morbidly adherent placenta.

METHODS

This retrospective study evaluated the association between maternal complications and a grayscale sonographic scoring system for adherent placenta before surgery. Criteria for adherent placenta included uteroplacental and uterobladder demarcation lines and the presence of lacunae. Placentas were classified into 4 stages: stage 0, normal placentation; stage 1, low probability of adherence; stage 2, moderate possibility of adherence; and stage 3, high suspicion of adherence. Placental adherence as assessed by a surgical team, estimated blood loss, and postoperative hospitalization days were determined for each group, as well as the rates of the need for packed blood cells, cryoprecipitate units, and hysterectomy.

RESULTS

One hundred nine women were included in the study. Twenty-six (23.8%) women were given a score of stage 0, 22 (20.2%) stage 1, 28 (25.7%) stage 2, and 33 (30.3%) stage 3. Linear regression analysis demonstrated that the sonographic staging was the only variable significantly associated with the number of packed cells or cryoprecipitate units transfused (P< .001) and a clinical diagnosis of adherent placenta (P< .001). In addition, both sonographic staging and a history of cesarean delivery were significantly associated with hysterectomy (P = .01; P = .03, respectively), treatment with any blood products (P< .001; P= .01), and the duration of postoperative hospitalization (P< .001; P = .006).

CONCLUSIONS

A scoring system based on simple grayscale parameters may be effective for antenatal risk assessment of maternal complications in cases of suspected morbidly adherent placenta.

A Case Report and Literature Review of Midtrimester Termination of Pregnancy Complicated by Placenta Previa and Placenta Accreta

Objective Concurrent placenta previa and placenta accreta increase the risk of massive obstetric hemorrhage. Despite extensive research on the management of placenta previa (including placenta accreta, increta, and percreta), the number and quality of previous studies are limited. We present a case of placenta accreta requiring an induced second-trimester abortion because of premature rupture of the membranes (PROM). Study Design Case report and review of the literature. Results A 41-year-old female presented at 20 weeks of gestation with placenta previa and PROM. Ultrasonography revealed placenta accreta with multiple placental lacunae. She then developed massive hemorrhaging just prior to a planned termination of pregnancy. We performed a hysterectomy with the intent of preserving life because of the failure of the placenta to detach and blood loss totaling 4,500 mL. Conclusion Previous studies suggest that second-trimester pregnancy terminations in cases of placenta previa which are not complicated with placenta accreta do not have a particularly high risk of hemorrhage. However, together with our case, the literature suggests that placenta previa complicated with placenta accreta presents a significant risk of hemorrhage both during delivery and intraoperatively. Further reports are needed to evaluate the most appropriate treatment options.

Ultrasound predictors of placental invasion: the Placenta Accreta Index

OBJECTIVE

We sought to apply a standardized evaluation of ultrasound parameters for the prediction of placental invasion in a high-risk population.

STUDY DESIGN

This was a retrospective review of gravidas with ≥1 prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta in the third trimester at our institution from 1997 through 2011. Sonographic images were reviewed by an investigator blinded to pregnancy outcome and sonography reports. Parameters assessed included loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Statistical analyses were performed using linear logistic regression and multiparametric analyses to generate a predictive equation evaluated using a receiver operating characteristic curve.

RESULTS

Of 184 gravidas who met inclusion criteria, 54 (29%) had invasion confirmed on hysterectomy specimen. All sonographic parameters were associated with placental invasion (P < .001). Constructing a receiver operating characteristic curve, the combination of smallest sagittal myometrial thickness, lacunae, and bridging vessels, in addition to number of cesarean deliveries and placental location, yielded an area under the curve of 0.87 (95% confidence interval, 0.80-0.95). Using logistic regression, a predictive equation was generated, termed the "Placenta Accreta Index." Each parameter was weighted to create a 9-point scale in which a score of 0-9 provided a probability of invasion that ranged from 2-96%, respectively.

CONCLUSION

Assignment of the Placenta Accreta Index may be helpful in predicting individual patient risk for morbidly adherent placenta.

A comparison of cell-free placental messenger ribonucleic acid and color Doppler ultrasound for the prediction of placental invasion in patients with placenta accreta

BACKGROUND

The aim of the present study was to comparison between cell-free placental messenger ribonucleic acid (mRNA) and Doppler ultrasound for the prediction of placental invasion in women with placenta accreta.

MATERIALS AND METHODS

In this cross-sectional study, 50 pregnant women at risk for placenta accreta underwent color Doppler and assessment of cell-free placental mRNA. Real-time reverse-transcription polymerase chain reaction was used for measurement of cell-free placental mRNA in maternal plasma. Based on the findings at cesarean delivery and histological examination, patients were divided into two groups of women with and without placenta accrete. To compare of the mean of mRNA levels between the two groups we used independent t-test and to compare of the mean of age and gestational age at sonography we used Mann-Whitney test. For determination of sensitivity and specificity and the cut-off point of mRNA levels we used the receiver operating characteristic curve.

RESULTS

A total of 50 women with a mean age of 30.24 ± 4.905 years entered the study and 12 (24%) patients were diagnosed with placenta accreta. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Doppler ultrasound were 83.3%, 78.9%, 56% and 94%, respectively. Results of our study showed if we consider a cut-off point equal to 3.325, with sensitivity and specificity of 0.917 and 0.789, respectively and the sensitivity, specificity, PPV and NPV of mRNA with were cut-off point of 3.325 were 91.7%, 78.9%, 57.9% and 96.8%, respectively.

CONCLUSIONS

Cell-free mRNA is an acceptable, easy made, functional test with sensitivity, specificity, PPV and NPV more than Doppler ultrasound for diagnosis and prediction of incidence of placenta accrete and we recommend the use of cell-free mRNA test for diagnosis of placenta accreta.