Ultrasonographic findings of placenta lacunae and a lack of a clear zone in cases with placenta previa and normal placenta

The Association of Serum Midkine Level with Invasion in Placenta Previa: A Case-Control Study from a Tertiary Reference Center

We aimed to examine the relationship between serum midkine levels and placental invasion in pregnant women with placenta previa. The study group consisted of 43 pregnant women diagnosed with placenta previa, whereas the control group consisted of 60 healthy pregnant women. Serum midkine levels were compared between pregnant women with placenta previa and the control group in this study's first part. Thereafter, the utility of midkine in the prediction of the abnormally invasive placenta (AIP) was investigated and optimal cutoff values were calculated. Significantly higher serum midkine level was observed in placenta previa cases than in the controls (1.16 ng/mL vs. 0.18 ng/mL, P < 0.001). Serum midkine level was also significantly higher in the AIP group among the placenta previa cases (P = 0.004). In the receiver operating characteristic analysis, the cutoff value of the midkine level in predicting AIP was 1.19 ng/mL. This study revealed that the serum midkine level is higher in pregnant women with AIP. Maternal serum midkine level may be used as a complementary biomarker to the radiological and clinical findings for the prediction of the AIP in placenta previa cases.

Pathologically diagnosed placenta accreta spectrum without placenta previa: a systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to assess clinical characteristics related to pathologically proven placenta accreta spectrum without placenta previa.

DATA SOURCES

A literature search of PubMed, the Cochrane database, and Web of Science was performed from inception to September 7, 2022.

STUDY ELIGIBILITY CRITERIA

The primary outcomes were invasive placenta (including increta or percreta), blood loss, hysterectomy, and antenatal diagnosis. In addition, maternal age, assisted reproductive technology, previous cesarean delivery, and previous uterine procedures were investigated as potential risk factors. The inclusion criteria were studies evaluating the clinical presentation of pathologically diagnosed PAS without placenta previa.

METHODS

Study screening was conducted after duplicates were identified and removed. The quality of each study and the publication bias were assessed. Forest plots and I2 statistics were calculated for each study outcome for each group. The main analysis was a random-effects analysis.

RESULTS

Among 2598 studies that were initially retrieved, 5 were included in the review. With the exception of 1 study, 4 studies were included in the meta-analysis. This meta-analysis showed that placenta accreta spectrum without placenta previa was associated with less risk of invasive placenta (odds ratio, 0.24; 95% confidence interval, 0.16-0.37), blood loss (mean difference, -1.19; 95% confidence interval, -2.09 to -0.28) and hysterectomy (odds ratio, 0.11; 95% confidence interval, 0.02-0.53), and more difficult to diagnose prenatally (odds ratio, 0.13; 95% confidence interval, 0.04-0.45) than placenta accreta spectrum with placenta previa. In addition, assisted reproductive technology and a previous uterine procedure were strong risk factors for placenta accreta spectrum without placenta previa, whhereas previous cesarean delivery was a strong risk factor for placenta accreta spectrum with placenta previa.

CONCLUSION

The differences in clinical aspects of placenta accreta spectrum with and without placenta previa need to be understood.

Diagnostic accuracy of ultrasound in the diagnosis of Placenta accreta spectrum: systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic accuracy of ultrasound and in the diagnosis of Placenta accreta spectrum (PAS).

DATA SOURCES

Screening of MEDLINE, CENTRAL, other bases from inception to February 2022 using the keywords related to placenta accreta, increta, percreta, morbidly adherent placenta, and preoperative ultrasound diagnosis.

STUDY ELIGIBILITY CRITERIA

All available studies- whether were prospective or retrospective- including cohort, case control and cross sectional that involved prenatal diagnosis of PAS using 2D or 3D ultrasound with subsequent pathological confirmation postnatal were included. Fifty-four studies included 5307 women fulfilled the inclusion criteria, PAS was confirmed in 2025 of them.

STUDY APPRAISAL AND SYNTHESIS METHODS

Extracted data included settings of the study, study type, sample size, participants characteristics and their inclusion and exclusion criteria, Type and site of placenta previa, Type and timing of imaging technique (2D, and 3D), severity of PAS, sensitivity and specificity of individual ultrasound criteria and overall sensitivity and specificity.

RESULTS

The overall sensitivity was 0.8703, specificity was 0.8634 with -0.2348 negative correlation between them. The estimate of Odd ratio, negative likelihood ratio and positive likelihood ratio were 34.225, 0.155 and 4.990 respectively. The overall estimates of loss of retroplacental clear zone sensitivity and specificity were 0.820 and 0.898 respectively with 0.129 negative correlation. The overall estimates of myometrial thinning, loss of retroplacental clear zone, the presence of bridging vessels, placental lacunae, bladder wall interruption, exophytic mass, and uterovesical hypervascularity sensitivities were 0.763, 0.780, 0.659, 0.785, 0.455, 0.218 and 0.513 while specificities were 0.890, 0.884, 0.928, 0.809, 0.975, 0.865 and 0.994 respectively.

CONCLUSIONS

The accuracy of ultrasound in diagnosis of PAS among women with low lying or placenta previa with previous cesarean section scars is high and recommended in all suspected cases.

TRIAL REGISTRATION

Number CRD42021267501.

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

BACKGROUND

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

AIMS

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Separation sign: novel ultrasound sign for ruling out diagnosis of placenta accreta spectrum

OBJECTIVE

To assess the performance of the 'separation sign' as a predictor of normal placental separation in a large cohort of women at risk for placenta accreta spectrum (PAS) and in a high-risk subgroup with placenta previa or anterior low-lying placenta and at least one previous Cesarean delivery.

METHODS

This was a prospective study of women at risk for PAS referred to a specialist clinic at between 22 and 38 weeks' gestation. All women underwent ultrasound assessment for the presence of the separation sign, which detects the difference in elasticity between the myometrium and the placenta, characterized by different rates of rebound after an ultrasound probe is used to apply pressure over the uteroplacental interface. When the sign is positive, the placenta appears to move relative to the myometrium, leading to the appearance or enhancement of the clear zone. The predictive performance of the separation sign for normal spontaneous placental separation at delivery was assessed.

RESULTS

Of the 194 included women, 163 had a positive separation sign, all of whom went on to have normal placental separation at delivery. Of the 24 women with a negative separation sign, three (12.5%) had normal placental separation and 21 (87.5%) were diagnosed with PAS. This yielded a sensitivity of 98.2% (95% CI, 94.8-99.6%) and specificity of 100% (95% CI, 83.9-100%). In the high-risk cohort (n = 35), a positive separation sign remained a reliable predictor of normal placental separation, with a positive predictive value of 100%, sensitivity of 88.9% (95% CI, 65.3-98.6%) and specificity of 100% (95% CI, 80.5-100%).

CONCLUSIONS

The separation sign could be a useful tool in women considered to be at risk for PAS, as it can facilitate the prediction of normal placental separation at delivery. This may prevent overtreatment, the associated iatrogenic morbidity and unnecessary allocation of clinical resources. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Third-trimester ultrasound for antenatal diagnosis of placenta accreta spectrum in women with placenta previa: results from the ADoPAD study

OBJECTIVE

To evaluate the performance of third-trimester ultrasound for the diagnosis of clinically significant placenta accreta spectrum disorder (PAS) in women with low-lying placenta or placenta previa.

METHODS

This was a prospective multicenter study of pregnant women aged ≥ 18 years who were diagnosed with low-lying placenta (< 20 mm from the internal cervical os) or placenta previa (covering the internal cervical os) on ultrasound at ≥ 26 + 0 weeks' gestation, between October 2014 and January 2019. Ultrasound suspicion of PAS was raised in the presence of at least one of these signs on grayscale ultrasound: (1) obliteration of the hypoechogenic space between the uterus and the placenta; (2) interruption of the hyperechogenic interface between the uterine serosa and the bladder wall; (3) abnormal placental lacunae. Histopathological examinations were performed according to a predefined protocol, with pathologists blinded to the ultrasound findings. To assess the ability of ultrasound to detect clinically significant PAS, a composite outcome comprising the need for active management at delivery and histopathological confirmation of PAS was considered the reference standard. PAS was considered to be clinically significant if, in addition to histological confirmation, at least one of these procedures was carried out after delivery: use of hemostatic intrauterine balloon, compressive uterine suture, peripartum hysterectomy, uterine/hypogastric artery ligation or uterine artery embolization. The diagnostic performance of each ultrasound sign for clinically significant PAS was evaluated in all women and in the subgroup who had at least one previous Cesarean section and anterior placenta. Post-test probability was assessed using Fagan nomograms.

RESULTS

A total of 568 women underwent transabdominal and transvaginal ultrasound examinations during the study period. Of these, 95 delivered in local hospitals, and placental pathology according to the study protocol was therefore not available. Among the 473 women for whom placental pathology was available, clinically significant PAS was diagnosed in 99 (21%), comprising 36 cases of placenta accreta, 19 of placenta increta and 44 of placenta percreta. The median gestational age at the time of ultrasound assessment was 31.4 (interquartile range, 28.6-34.4) weeks. A normal hypoechogenic space between the uterus and the placenta reduced the post-test probability of clinically significant PAS from 21% to 5% in women with low-lying placenta or placenta previa in the third trimester of pregnancy and from 62% to 9% in the subgroup with previous Cesarean section and anterior placenta. The absence of placental lacunae reduced the post-test probability of clinically significant PAS from 21% to 9% in women with low-lying placenta or placenta previa in the third trimester of pregnancy and from 62% to 36% in the subgroup with previous Cesarean section and anterior placenta. When abnormal placental lacunae were seen on ultrasound, the post-test probability of clinically significant PAS increased from 21% to 59% in the whole cohort and from 62% to 78% in the subgroup with previous Cesarean section and anterior placenta. An interrupted hyperechogenic interface between the uterine serosa and bladder wall increased the post-test probability for clinically significant PAS from 21% to 85% in women with low-lying placenta or placenta previa and from 62% to 88% in the subgroup with previous Cesarean section and anterior placenta. When all three sonographic markers were present, the post-test probability for clinically significant PAS increased from 21% to 89% in the whole cohort and from 62% to 92% in the subgroup with previous Cesarean section and anterior placenta.

CONCLUSIONS

Grayscale ultrasound has good diagnostic performance to identify pregnancies at low risk of PAS in a high-risk population of women with low-lying placenta or placenta previa. Ultrasound may be safely used to guide management decisions and concentrate resources on patients with higher risk of clinically significant PAS. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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.

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.

Introducing an efficient model for the prediction of placenta accreta spectrum using the MCP regression approach based on sonography indexes: how efficient is sonography in diagnosing accreta?

Background

For the first time, we aimed to introduce a model for prediction of placenta accreta spectrum (PAS), using existing sonography indices.

Methods

Women with a history of Cesarean sections were included. Participants were categorized “high risk” for PAS if the placenta was previa or low-lying.

Sonography indices including abnormal placental lacuna, loss of clear zone, bladder wall interruption, myometrial thinning, placental bulging, exophytic mass, utero-vesical hypervascularity, subplacental hypervascularity, existence of bridging vessels, and lacunar flow, were registered.

To investigate simultaneous effects of 15 variables on PAS, Minimax Concave Penalty (MCP) was used.

Results

Among 259 participants, 74 (28.5%) were high risk and 43 individuals had PASs.

All sonography indices were higher among patient with PAS (p < 0.001) in the high risk group.

Our model showed that utero-vesical hypervascularity, bladder interruption and new lacunae have significant contribution in PAS. Optimal cut off point was p = 0.51 in ROC analysis. Probability of PAS for women with lacunae was between 96 and 100% and probability of PAS for women without lacunae was between 0 to 7%, therefore accuracy of the proposed model was equal to 100%.

Conclusions

Using the introduced model based on three factors of abnormal lacuna structures (grades 2 and 3), bladder wall interruption and utero-vesical vascularity, 100% of all cases of PASs are diagnosable. If supported by future studies our model eliminates the need for other imaging assessments for diagnosis of invasive placentation among high risk women with previous history of Cesarean sections.

Epidemiology of placenta previa accreta: a systematic review and meta-analysis

OBJECTIVE

To estimate the prevalence and incidence of placenta previa complicated by placenta accreta spectrum (PAS) and to examine the different criteria being used for the diagnosis.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Google Scholar, ClinicalTrials.gov and MEDLINE were searched between August 1982 and September 2018.

ELIGIBILITY CRITERIA

Studies reporting on placenta previa complicated by PAS diagnosed in a defined obstetric population.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers performed the data extraction using a predefined protocol and assessed the risk of bias using the Newcastle-Ottawa scale for observational studies, with difference agreed by consensus. The primary outcomes were overall prevalence of placenta previa, incidence of PAS according to the type of placenta previa and the reported clinical outcomes, including the number of peripartum hysterectomies and direct maternal mortality. The secondary outcomes included the criteria used for the prenatal ultrasound diagnosis of placenta previa and the criteria used to diagnose and grade PAS at birth.

RESULTS

A total of 258 articles were reviewed and 13 retrospective and 7 prospective studies were included in the analysis, which reported on 587 women with placenta previa and PAS. The meta-analysis indicated a significant (p<0.001) heterogeneity between study estimates for the prevalence of placenta previa, the prevalence of placenta previa with PAS and the incidence of PAS in the placenta previa cohort. The median prevalence of placenta previa was 0.56% (IQR 0.39-1.24) whereas the median prevalence of placenta previa with PAS was 0.07% (IQR 0.05-0.16). The incidence of PAS in women with a placenta previa was 11.10% (IQR 7.65-17.35).

CONCLUSIONS

The high heterogeneity in qualitative and diagnostic data between studies emphasises the need to implement standardised protocols for the diagnoses of both placenta previa and PAS, including the type of placenta previa and grade of villous invasiveness.

PROSPERO REGISTRATION NUMBER

CRD42017068589.

Risk factors for severe postpartum haemorrhage during caesarean section for placenta praevia

The objective of this study was to evaluate the value of clinical and ultrasound risk factors in predicting severe postpartum haemorrhage (PPH) (≥1.5 L) in pregnancies undergoing caesarean section for placenta praevia. This cohort consists of all cases of placenta praevia undergoing caesarean delivery over a period of 5 years in a service unit. Patients and their delivery data were retrieved from an obstetric database. Ultrasound features were prospectively recorded before caesarean section. The incidence of caesarean section for placenta praevia was 0.98% (n = 215). Of these, 12.1% (n = 26) had severe PPH. A logistic regression model showed that major praevia, antepartum haemorrhage before delivery and anterior placenta remained significant factors associated with severe PPH. The sensitivity/specificity and positive/negative predictive value of the model are 96.2%, 59.8%, 24.8% and 99.1%, respectively. Our model had high sensitivity and negative predictive value for severe PPH during caesarean section for placenta praevia.Impact statementWhat is already known on this subject? Placenta praevia is known to be one of the leading causes of severe PPH. Many risk factors have been associated with severe bleeding during caesarean section for placenta praevia. However, the importance of individual factors in predicting pregnancy outcome remains controversial.What the results of this study add? Our model includes only three simple parameters, namely the presence of significant antepartum haemorrhage (APH) from the history, and anterior or posterior placenta and major or minor praevia from ultrasound findings, but could predict up to 96.2% of all severe PPH. More importantly, the absence of APH, a posterior minor praevia, was associated with a negative predictive value of 99.1% of severe PPH, implying that such cases could be treated as 'normal' low risk caesarean sections.What the implications are of these findings for clinical practice and/or further research? This simple model would allow differential pre-operative counselling of patients on risks and complications, planning and preparation of operation, allocation of staff as well as in contingency measures to be taken during operation. The establishment of a differential protocol for placenta praevia based on these simple risks factors and a prospective trial of such a protocol is suggested.

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.

Diagnostic accuracy of cystoscopy and ultrasonography in the prenatal diagnosis of abnormally invasive placenta

The aim of this study was to compare the accuracy of cystoscopy and ultrasonography for the prenatal diagnosis of abnormally invasive placenta (AIP), including its subgroups: placenta accreta (PA), placenta increta (PI), and placenta percreta (PP).A retrospective observational study including a total of 85 pregnant women at high risk for AIP underwent prenatal cystoscopy and ultrasonography evaluations. The sensitivity (Se), specificity (Sp), positive predictive value, negative predictive value, and exact diagnosed were calculated and compared for both cystoscopy and ultrasonography. Se and Sp values of cystoscopy and ultrasonography were compared by means of the McNemar test.Of the 85 patients, there were 24 (28.2%) PA, 35 (41.2%) PI, 4 (4.7%) PP, and 22 (25.9%) nonadherent placenta. The mean maternal age and gestational age of delivery were 31.88 ± 4.42 years and 36.14 ± 1.84 weeks, respectively. No one was found to develop any complications with cystoscopy like urinary tract infection, or ureteral injury or perforations. Se in the diagnosis of AIP was 50.8% with ultrasonography and 61.9% for cystoscopy. Sp was 86.4% with cystoscopy and 72.7% for ultrasonography. In subgroups, Se with cystoscopy was 25.0%, 62.9%, and 100.0% in PA, PI, and PP, respectively, and 37.5%, 74.3%, and 100.0%, respectively, for ultrasonography; Sp remained unchanged with 86.4% for cystoscopy and 72.7% for ultrasonography. After McNemar test, no difference was found in either Se or Sp between cystoscopy and ultrasonography in AIP and its subgroups.According to the depth of invasion, the diagnostic value of cystoscopy and ultrasonography is all conspicuous increased and they have similar test validity for prenatal diagnosis of AIP and its subgroups.

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

Placenta accreta spectrum is a complex obstetric complication associated with high maternal morbidity. It is a relatively new disorder of placentation, and is the consequence of damage to the endometrium-myometrial interface of the uterine wall. When first described 80 years ago, it mainly occurred after manual removal of the placenta, uterine curettage, or endometritis. Superficial damage leads primarily to an abnormally adherent placenta, and is diagnosed as the complete or partial absence of the decidua on histology. Today, the main cause of placenta accreta spectrum is uterine surgery and, in particular, uterine scar secondary to cesarean delivery. In the absence of endometrial reepithelialization of the scar area the trophoblast and villous tissue can invade deeply within the myometrium, including its circulation, and reach the surrounding pelvic organs. The cellular changes in the trophoblast observed in placenta accreta spectrum are probably secondary to the unusual myometrial environment in which it develops, and not a primary defect of trophoblast biology leading to excessive invasion of the myometrium. Placenta accreta spectrum was separated by pathologists into 3 categories: placenta creta when the villi simply adhere to the myometrium, placenta increta when the villi invade the myometrium, and placenta percreta where the villi invade the full thickness of the myometrium. Several prenatal ultrasound signs of placenta accreta spectrum were reported over the last 35 years, principally the disappearance of the normal uteroplacental interface (clear zone), extreme thinning of the underlying myometrium, and vascular changes within the placenta (lacunae) and placental bed (hypervascularity). The pathophysiological basis of these signs is due to permanent damage of the uterine wall as far as the serosa, with placental tissue reaching the deep uterine circulation. Adherent and invasive placentation may coexist in the same placental bed and evolve with advancing gestation. This may explain why no single, or set combination of, ultrasound sign(s) was found to be specific for the depth of abnormal placentation, and accurate for the differential diagnosis between adherent and invasive placentation. Correlation of pathological and clinical findings with prenatal imaging is essential to improve screening, diagnosis, and management of placenta accreta spectrum, and standardized protocols need to be developed.

Accreta placentation: a systematic review of prenatal ultrasound imaging and grading of villous invasiveness

BACKGROUND

Determining the depth of villous invasiveness before delivery is pivotal in planning individual management of placenta accreta. We have evaluated the value of various ultrasound signs proposed in the international literature for the prenatal diagnosis of accreta placentation and assessment of the depth of villous invasiveness.

OBJECTIVE

We undertook a PubMed and MEDLINE search of the relevant studies published from the first prenatal ultrasound description of placenta accreta in 1982 through March 30, 2016, using key words "placenta accreta," "placenta increta," "placenta percreta," "abnormally invasive placenta," "morbidly adherent placenta," and "placenta adhesive disorder" as related to "sonography," "ultrasound diagnosis," "prenatal diagnosis," "gray-scale imaging," "3-dimensional ultrasound", and "color Doppler imaging."

STUDY DESIGN

The primary eligibility criteria were articles that correlated prenatal ultrasound imaging with pregnancy outcome. A total of 84 studies, including 31 case reports describing 38 cases of placenta accreta and 53 series describing 1078 cases were analyzed. Placenta accreta was subdivided into placenta creta to describe superficially adherent placentation and placenta increta and placenta percreta to describe invasive placentation.

RESULTS

Of the 53 study series, 23 did not provide data on the depth of villous myometrial invasion on ultrasound imaging or at delivery. Detailed correlations between ultrasound findings and placenta accreta grading were found in 72 cases. A loss of clear zone (62.1%) and the presence of bridging vessels (71.4%) were the most common ultrasound signs in cases of placenta creta. In placenta increta, a loss of clear zone (84.6%) and subplacental hypervascularity (60%) were the most common ultrasound signs, whereas placental lacunae (82.4%) and subplacental hypervascularity (54.5%) were the most common ultrasound signs in placenta percreta. No ultrasound sign or a combination of ultrasound signs were specific of the depth of accreta placentation.

CONCLUSION

The wide heterogeneity in terminology used to describe the grades of accreta placentation and differences in study design limits the evaluation of the accuracy of ultrasound imaging in the screening and diagnosis of placenta accreta. This review emphasizes the need for further prospective studies using a standardized evidence-based approach including a systematic correlation between ultrasound signs of placenta accreta and detailed clinical and pathologic examinations at delivery.

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.

Placenta Accreta in a Woman with Escherichia coli Chorioamnionitis with Intact Membranes

Background. Escherichia coli (E. coli) associated intrauterine infections with intact membranes are extremely rare. Case. A 30-year-old multiparous female presented at 26 weeks' gestation with clinical signs of chorioamnionitis but physical examination suggested intact membranes. Her dietary history was concerned with Listeriosis. An amniocentesis was performed. Shortly thereafter, the mother developed septic shock and an urgent Cesarean delivery was performed. The patient required a peripartum hysterectomy for placenta accreta. Amniotic fluid cultures grew E. coli.

Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of placenta accreta

Purpose

To evaluate the accuracy of ultrasonography and magnetic resonance imaging (MRI) in the diagnosis of placenta accreta and to define the most relevant specific ultrasound and MRI features that may predict placental invasion.

Material and Methods

This study was approved by the institutional review board of the French College of Obstetricians and Gynecologists. We retrospectively reviewed the medical records of all patients referred for suspected placenta accreta to two university hospitals from 01/2001 to 05/2012. Our study population included 42 pregnant women who had been investigated by both ultrasonography and MRI. Ultrasound images and MRI were blindly reassessed for each case by 2 raters in order to score features that predict abnormal placental invasion.

Results

Sensitivity in the diagnosis of placenta accreta was 100% with ultrasound and 76.9% for MRI (P = 0.03). Specificity was 37.5% with ultrasonography and 50% for MRI (P = 0.6). The features of greatest sensitivity on ultrasonography were intraplacental lacunae and loss of the normal retroplacental clear space. Increased vascularization in the uterine serosa-bladder wall interface and vascularization perpendicular to the uterine wall had the best positive predictive value (92%). At MRI, uterine bulging had the best positive predictive value (85%) and its combination with the presence of dark intraplacental bands on T2-weighted images improved the predictive value to 90%.

Conclusion

Ultrasound imaging is the mainstay of screening for placenta accreta. MRI appears to be complementary to ultrasonography, especially when there are few ultrasound signs.

Prenatal identification of invasive placentation using ultrasound: systematic review and meta-analysis

OBJECTIVE

The accuracy of prospective sonographic prenatal detection of invasive placentation is unclear. The objective of this study was to conduct a systematic review and meta-analysis to assess the performance of ultrasound in at-risk women for prenatal identification of invasive placentation.

METHODS

MEDLINE, EMBASE, The Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE) and The Cochrane Central Register of Controlled Trials (CENTRAL) were searched using the search terms 'placenta accreta', 'placenta increta', 'placenta percreta', 'ultrasound', 'magnetic resonance imaging (MRI)', 'invasive placenta' and 'infiltrative placenta'. Two authors independently abstracted data from the articles. Sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), the diagnostic odds ratio (DOR) and their 95% CIs for each study were calculated. Forest plots and summary receiver-operating characteristics curves were produced. Between-study heterogeneity was explored both graphically and statistically. The MOOSE (meta-analysis of observational studies in epidemiology) guidelines were followed.

RESULTS

Twenty-three studies involving 3707 pregnancies at risk for invasive placentation were included. The overall performance of ultrasound for the antenatal detection of invasive placentation was as follows: sensitivity, 90.72 (95% CI, 87.2-93.6)%; specificity, 96.94 (95% CI, 96.3-97.5)%; LR+, 11.01 (95% CI, 6.1-20.0); LR-, 0.16 (95% CI, 0.11-0.23); and DOR, 98.59 (95% CI, 48.8-199.0). Among the different ultrasound signs, color Doppler had the best predictive accuracy (sensitivity, 90.74 (95% CI, 85.2-94.7)%; specificity, 87.68 (95% CI, 84.6-90.4)%; LR+, 7.77 (95% CI, 3.3-18.4); LR-, 0.17 (95% CI, 0.10-0.29); and DOR, 69.02 (95% CI, 22.8-208.9)).

CONCLUSIONS

Ultrasound has a high accuracy for prenatal diagnosis of disorders of invasive placentation in high-risk women. The use of color Doppler improves the test performance.

The sonographic appearance and obstetric management of placenta accreta

Placenta accreta is a condition of abnormal placental implantation in which the placental tissue invades beyond the decidua basalis. It may invade into or even through the myometrium and adjacent organs, such as the urinary bladder. The incidence has been rising in recent years. It is one of the important obstetric complications nowadays, leading to significant maternal morbidity and mortality. In the past, this condition was often diagnosed at the time of delivery when massive and unexpected hemorrhage occurred. Hysterectomy, associated with significant physical and psychological consequences, was usually the only management option. As more obstetricians have become aware of this condition, early identification with antenatal imaging diagnostic technology has become possible. Ultrasound scan plays an important role in the antenatal diagnosis. Various sonographic features with different specificity and sensitivity have been described in the literature. In equivocal cases, magnetic resonance imaging may be helpful. With such information, more accurate counseling can be offered to the mothers and their families before delivery. The delivery can also be arranged at a favorable time and in an institution where multidisciplinary support is available. Input from a hematologist, interventional radiologist, intensive care physician, urology surgeon, and/or other specialist are desirable. Apart from hysterectomy, various forms of conservative management can also be considered when the diagnosis is made prior to delivery. Fertility can therefore be preserved. After delivery, with or without hysterectomy performed, psychological support to the mothers and their families is essential.

Analysis of the predictable variables for placenta accreta without placenta previa

OBJECTIVES

To clarify the predictive variables for adherence of the placenta (AP) in cases without placenta previa.

METHODS

A prospective cohort study was conducted between 2008 and 2010. Patients without placenta previa who delivered singleton babies after 36 weeks' gestation were enrolled. The maternal and ultrasonographic variables associated with AP were evaluated at the time of admission for delivery.

RESULTS

A total of 2834 consecutive subjects were included. Placenta accreta without placenta previa was observed in six cases (0.2 %). Two cases in which the placenta was located on the previous uterine scar had AP, but AP was found only in 0.1 % of cases in which the placenta was not on the previous scar (p < 0.001). AP was frequently observed in cases with a history of previous uterine surgery compared to cases without a history [(1.9 vs. 0.1 %) p < 0.001]. AP was observed in 33 % of cases in which no retroplacental clear zone was detected, whereas AP was observed in only 0.1 % of cases with a clear zone (p < 0.001).

CONCLUSION

A past history of uterine surgery, ultrasonographic findings of no retroplacental clear zone, and a placenta on the uterine scar were associated with AP in cases without placenta previa.