Prenatal sonographic diagnosis of placenta accreta--impact on maternal and neonatal outcomes

Predictive Value and Limitations of the Placenta Accreta Index: A Systematic Review

Our systematic review highlights that multiparametric PAI score assessment is a consistent tool with high sensitivity and specificity for prenatal prediction for placenta accreta spectrum (PAS) in high-risk population with anterior placenta previa or low-lying placenta and prior cesarean deliveries. A systematic search was conducted on November 1, 2022, of MEDLINE via PubMed, Scopus, Web of Science Core Collection, Cochrane Library, and Google Scholar to identify relevant studies (PROSPERO ID # CRD42022368211). A total of 11 articles met our inclusion criteria, representing the data of a total of 1,044 cases. Women with PAS had an increased mean PAI total score, compared to those without PAS. Limitations of the PAI are most studies were conducted in developing countries in high-risk population which limit the global generalizability of findings. Heterogeneity of reported data did not allow to perform meta-analysis.

Comparison of maternal outcomes and clinical characteristics of prenatally vs nonprenatally diagnosed placenta accreta spectrum: a systematic review and meta-analysis

OBJECTIVE

This study aimed to compare maternal outcomes of prenatally and nonprenatally diagnosed placenta accreta spectrum.

DATA SOURCES

A systematic literature search was performed in PubMed, the Cochrane database, and Web of Science until November 28, 2022.

STUDY ELIGIBILITY CRITERIA

Studies comparing the clinical presentation of prenatally and nonprenatally diagnosed placenta accreta spectrum were included. The primary outcomes were emergent cesarean delivery, hysterectomy, blood loss volume, number of transfused blood product units, urological injury, coagulopathy, reoperation, intensive care unit admission, and maternal death. In addition, the pooled mean values for blood loss volume and the number of transfused blood product units were calculated. The secondary outcomes included maternal age, gestational age at birth, nulliparity, previous cesarean delivery, previous uterine procedure, assisted reproductive technology, placenta increta and percreta, and placenta previa.

METHODS

Study screening was performed 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

Overall, 415 abstracts and 157 full-text studies were evaluated. Moreover, 31 studies were analyzed. Prenatally diagnosed placenta accreta spectrum was associated with a significantly lower rate of emergency cesarean delivery (odds ratio, 0.37; 95% confidence interval, 0.21-0.67), higher hysterectomy rate (odds ratio, 1.98; 95% confidence interval, 1.02-3.83), lower blood loss volume (mean difference, -0.65; 95% confidence interval, -1.17 to -0.13), and lower number of transfused red blood cell units (mean difference, -1.96; 95% confidence interval, -3.25 to -0.68) compared with nonprenatally diagnosed placenta accreta spectrum. The pooled mean values for blood loss volume and the number of transfused blood product units tended to be lower in the prenatally diagnosed placenta accreta spectrum groups than in the nonprenatally diagnosed placenta accreta spectrum groups. Nulliparity (odds ratio, 0.14; 95% confidence interval, 0.10-0.20), previous cesarean delivery (odds ratio, 6.81; 95% confidence interval, 4.12-11.25), assisted reproductive technology (odds ratio, 0.19; 95% confidence interval, 0.06-0.61), placenta increta and percreta (odds ratio, 3.97; 95% confidence interval, 2.24-7.03), and placenta previa (odds ratio, 6.81; 95% confidence interval, 4.12-11.25) showed statistical significance. No significant difference was found for the other outcomes.

CONCLUSION

Despite its severity, the positive effect of prenatally diagnosed placenta accreta spectrum on outcomes underscores the necessity of a prenatal diagnosis. In addition, the pooled mean values provide a preoperative preparation guideline.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

KEY POINTS

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

Relationship between the Prenatal Diagnosis of Placenta Acreta Spectrum and Lower Use of Blood Components

OBJECTIVE

 To describe the clinical results of patients admitted and managed as cases of placenta accreta spectrum (PAS) at a Central American public hospital and the influence of the prenatal diagnosis on the condition.

MATERIALS AND METHODS

 A retrospective analysis of PAS patients treated at Hospital Bertha Calderón Roque, in Managua, Nicaragua, between June 2017 and September 2021. The diagnostic criteria used were those of the International Federation of Gynecology and Obstetrics (Fédération Internationale de Gynécologie et d'Obstétrique, FIGO, in French). The population was divided into patients with a prenatal ultrasonographic diagnosis of PAS (group 1) and those whose the diagnosis of PAS was established at the time of the caesarean section (group 2).

RESULTS

 During the search, we found 103 cases with a histological and/or clinical diagnosis of PAS; groups 1 and 2 were composed of 51 and 52 patients respectively. Regarding the clinical results of both groups, the patients in group 1 presented a lower frequency of transfusions (56.9% versus 96.1% in group 2), use of a lower number of red blood cell units (RBCUs) among those undergoing transfusions (median: 1; interquartile range: [IQR]: 0-4 versus median: 3; [IQR]: 2-4] in group 2), and lower frequency of 4 or more RBCU transfusions (29.4% versus 46.1% in group 2). Group 1 also exhibited a non-significant trend toward a lower volume of blood loss (1,000 mL [IQR]: 750-2,000 mL versus 1,500 mL [IQR]: 1,200-1,800 mL in group 2), and lower requirement of pelvic packing (1.9% versus 7.7% in group 2).

CONCLUSION

 Establishing a prenatal diagnosis of PAS is related to a lower frequency of transfusions. We observed a high frequency of prenatal diagnostic failures of PAS. It is a priority to improve prenatal detection of this disease.

The Society for Pediatric Pathology Task Force grading system for placenta accreta spectrum and its correlation with clinical outcomes

BACKGROUND

The terminology and diagnostic criteria presently used by pathologists to report placenta accreta spectrum is inconsistent and does not reflect current knowledge of the pathogenesis of this disease.

OBJECTIVE

In 2020, the perinatal subcommittee of the Society for Pediatric Pathology Placenta Accreta Task Force proposed a new pathologic grading system for placenta accreta spectrum. We sought to correlate the clinical outcomes with the classification into each group in the new placenta accreta spectrum grading system.

STUDY DESIGN

The pathology reports of patients with histopathologic confirmation of placenta accreta spectrum were reviewed in 2 academic referral centers by placental pathologists. Pathologic grading was assigned based on the new grading system according to which placenta accreta spectrum is categorized into 5 groups depending on the depth of invasion, from grade p1 with no invasion into the uterine wall to grade p3E with invasion beyond the uterine wall to the adjacent organs. Patient characteristics and clinical outcomes were compared among these groups. A univariate analysis was performed, and a multivariate linear or binomial regression was employed when needed.

RESULTS

A total of 683 patients with placenta accreta spectrum were identified. Of those, 407 were included for histology review. There were 92 patients (23%) categorized into the grade p1 group, 74 (18%) in the grade p2 group, 84 (20%) in the grade p3A group, 121 (30%) in the grade p3D group, and 36 (9%) in the grade p3E group. There was a significant association between the pathology grading and the number of red blood cells transfused (β=1.14; 95% confidence interval, 0.48-1.79) and the postoperative complications including the rate of readmission (risk ratio, 1.93; 95% confidence interval, 1.26-2.94) and bladder injury (risk ratio, 1.81; 95% confidence interval, 1.23-2.68) after adjustment for antenatal diagnosis and other variables. The pathology grading was not associated with the estimated blood loss (P=.072).

CONCLUSION

The new pathology grading system accurately reflects maternal outcomes and complications of placenta accreta spectrum. We encourage the utilization of this new pathologic grading system because it is designed to omit discrepancies in placenta accreta spectrum reporting and to standardize communication.

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

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

Prediction of cesarean hysterectomy in placenta previa complicated with prior cesarean: a retrospective study

Background

The prevalence of both placenta previa and cesarean are on the rise. Multiple adverse outcomes are critically increased when placenta previa is subsequent to prior cesarean. The purpose of the present study is to develop a pre-surgical method for predicting adverse outcomes in pregnancy complicated with both placenta previa and prior cesarean.

Methods

Clinical data was obtained from the medical history system at the First Affiliated Hospital of Sun Yat-sen University from February 2003 to December 2016. All cases with a final diagnosis of “placenta previa/low lying placenta (ICD:O44.001-105)” and “scarred uterus complicated with pregnancy (ICD: O34.200-202)” were collected and reviewed. Hysterectomy was taken as the primary outcome; and blood loss was taken as the secondary outcome.

Results

Of 219 pregnant women in the final analysis, 25 received a hysterectomy following delivery, and 48 had blood loss exceeding 1000 ml. Pre-surgical risk factors for hysterectomy are ultrasonic signs of vascular lacunae, central placenta previa, and loss of normal hypoechoic retroplacental zone. A pre-surgical predictive equation referred to as “Hysterectomy Index in Placenta Previa with Prior cesarean (HIPs)” was generated and each risk factor was weighted to create an 8-point scale. This index yielded an area under the curve of 0.972 for the prediction of hysterectomy.

Conclusions

Application of the HIPs score may provide an effective pre-surgical prediction of cesarean hysterectomy in pregnant women complicated with both placenta previa and prior cesarean.

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.

Management of patients with placenta accreta spectrum disorders who underwent pregnancy terminations in the second trimester: A retrospective study

PURPOSE

To analyse the management of patients with placenta accreta spectrum (PAS) disorders who underwent 2^nd trimester pregnancy terminations.

METHOD

The records of patients with PAS disorders who underwent 2^nd trimester pregnancy terminations were collected and analysed.

RESULTS

Twenty-eight patients were included; 8 (28.6%) patients received prenatal diagnoses and 20 (71.4%) patients received postnatal diagnoses. In the prenatal diagnosis group, scheduling hysterotomy and placenta removal were performed in 5 patients with complete placenta previa and previous caesarean delivery without hysterectomy or postpartum haemorrhage, and medical termination was performed in 3 patients, 2 of whom retained the placenta in situ. In the postnatal diagnosis group, the placenta remained in situ in 11 patients, and in 13 (46.4%) patients overall, adjuvant treatments were applied to the patients, and the abnormally implanted placenta was passed 43.5 (range: 7-102) days after termination. A complication associated with the placenta left in situ included intrauterine infection in one case. Uterus preservation was achieved in all the patients.

CONCLUSIONS

For patients with PAS disorders with complete placenta previa and previous caesarean delivery, hysterotomy is a safe choice for terminating a 2^nd trimester pregnancy. When it is impossible to manually remove the placenta, leaving the placenta in situ with the administration of adjuvant treatment is a good choice for uterus preservation.

Prevalence and main outcomes of placenta accreta spectrum: a systematic review and meta-analysis

OBJECTIVE DATA

The objective of this study was to evaluate the prevalence of placenta accreta spectrum in general population studies and the main maternal outcomes at delivery.

STUDY

We searched PubMed, Google Scholar, clinicalTrials.gov, and MEDLINE between 1982 and 2018. Articles that provided data on the number of cases of placenta accreta spectrum per pregnancies, births, or deliveries in a defined population were used.

STUDY APPRAISAL AND SYNTHESIS METHODS

Study characteristics were evaluated by 2 independent reviewers who used a predesigned protocol. Primary outcomes were the prevalence of placenta accreta spectrum and clinical diagnostic data at birth; the pathologic criteria were used to confirm the diagnosis. Secondary outcomes included cases that required transfusion, incidence of peripartum hysterectomy, and maternal mortality rates. Heterogeneity between studies was analyzed with the Cochran's Q-test and the I² statistics.

RESULTS

Of the 98 full-text studies that were identified, 29 articles met the defined criteria and included 22 retrospective and 7 prospective studies comprising 7001 cases of placenta accreta spectrum of 5,719,992 births. Prevalence rates ranged from 0.01-1.1% with an overall pooled prevalence of 0.17% (95% confidence interval, 0.14-0.19). Only 10 studies provided detailed histopathologic data. The pool prevalence for the adherent vs the invasive grades was 0.5 (95% confidence interval, 0.3-0.36) and 0.3 (95% confidence interval, 0.2-0.4) per 1000 births, respectively. The pooled incidence for peripartum hysterectomy was 52.2% (95% confidence interval, 38.3-66.4; I²=99.8%) and 46.9% (95 % confidence interval, 34-59.9; I²=98.8%) for hemorrhage that required transfusion. The pooled estimate of maternal death was 0.05% (95% confidence interval, 0.06-0.69; I²=73%). We found large amounts of heterogeneity between studies for all parameters and further quantification was limited because of methodologic inconsistencies between studies with regards to clinical criteria that were used for the diagnosis of the condition at birth and the histopathologic confirmation of the diagnosis and differential diagnosis between adherent and invasive accreta placentation.

CONCLUSION

This meta-analysis indicated wide variation between studies for the prevalence rate of placenta accreta spectrum and for the different grades of accreta placentation that highlighted the need for consistency in definitions that are used to describe placenta accreta spectrum at birth and in the reporting of this increasing common obstetric complication.

Influence of prenatal diagnosis of abnormally invasive placenta on maternal outcome: systematic review and meta-analysis

OBJECTIVE

To ascertain the impact of prenatal diagnosis on surgical outcome of women affected by abnormally invasive placenta (AIP).

METHODS

MEDLINE, EMBASE, CINAHL and Cochrane databases were searched. Observed outcomes included: gestational age at birth (weeks), amount of blood loss (L), units of red blood cells (RBC), platelets (PLT) and fresh frozen plasma (FFP) transfused, length of stay in hospital and the intensive care unit (ICU) (days), urinary tract injury and infection. Only studies reporting the occurrence of any of the explored outcomes in women with a prenatal compared with an intrapartum diagnosis of AIP were considered eligible for inclusion. Random-effect head-to-head meta-analyses were used to analyze the data.

RESULTS

Thirteen studies were included. Women with a prenatal diagnosis of AIP had less blood loss during surgery (mean difference (MD), -0.87; 95% CI, -1.5 to -0.23), had fewer units of RBC (MD, -1.45; 95% CI, -2.9 to -0.04) and FFP (MD, -1.73; 95% CI, -3.3 to -0.2) transfused, and delivered earlier (MD, 1.33 weeks; 95% CI, -2.23 to -0.43) compared with those with an intrapartum diagnosis. The risk of admission to an ICU and length of in-hospital and in-ICU stay were not different between the groups. Prenatal diagnosis of AIP was associated with a higher risk of urinary-tract injury (odds ratio, 2.5; 95% CI, 1.3-4.6), mainly due to the higher prevalence of placenta percreta in the group with AIP diagnosed prenatally.

CONCLUSION

Prenatal diagnosis of AIP is associated with reduced hemorrhagic morbidity compared with cases in which such anomalies are detected at delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Abnormal placentation: Current evidence and review of the literature

Abnormal placentation often requires the involvement of a multidisciplinary team of medical caregivers. Practicing Obstetrics is a challenging and skillful duty. This is more obvious in cases of abnormal placentation, which represents one of the most dangerous and complex clinical conditions in materno-fetal medicine. Pathological placentation involves position and invasion abnormalities and represents a serious and potentially life-threatening condition for both the pregnant woman and the fetus. The dramatic increase in cesarean section rates is an important factor which could explain the rapid raise in abnormal placentation cases, which were considered rare a few years ago. Nevertheless, the scientific armamentarium sometimes seems to be poor and this could be explained by the fact that treatment options are offered too late, since this condition is often detected late, entailing higher patients' risks. In fact, the later the diagnosis is made the poorer the prognosis is for cases of abnormal placentation. Given that abnormal placentation is constantly increasing, the scientific community should aim at early diagnosis and appropriate management of such cases based on the best evidence available. Future improvement of knowledge and practice lies in perspective, preferably randomized studies so that we obtain high quality of evidence which is still needed. The purpose of this study is to review the current literature and to update the available scientific knowledge on the topic of abnormal placentation which is an emerging issue which clinicians should learn to deal with, considering its continuous increase in the last years.

Prenatal ultrasound diagnosis and outcome of placenta previa accreta after cesarean delivery: a systematic review and meta-analysis

BACKGROUND

Women with a history of previous cesarean delivery, presenting with a placenta previa, have become the largest group with the highest risk for placenta previa accreta.

OBJECTIVE

The objective of the study was to evaluate the accuracy of ultrasound imaging in the prenatal diagnosis of placenta accreta and the impact of the depth of villous invasion on management in women presenting with placenta previa or low-lying placenta and with 1 or more prior cesarean deliveries.

STUDY DESIGN AND DATA SOURCES

We searched PubMed, Google Scholar, clinicalTrials.gov, and MEDLINE for studies published between 1982 and November 2016.

STUDY ELIGIBILITY CRITERIA

Criteria for the study were cohort studies that provided data on previous mode of delivery, placenta previa, or low-lying placenta on prenatal ultrasound imaging and pregnancy outcome. The initial search identified 171 records, of which 5 retrospective and 9 prospective cohort studies were eligible for inclusion in the quantitative analysis.

STUDY APPRAISAL AND SYNTHESIS METHODS

The studies were scored on methodological quality using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

The 14 cohort studies included 3889 pregnancies presenting with placenta previa or low-lying placenta and 1 or more prior cesarean deliveries screened for placenta accreta. There were 328 cases of placenta previa accreta (8.4%), of which 298 (90.9%) were diagnosed prenatally by ultrasound. The incidence of placenta previa accreta was 4.1% in women with 1 prior cesarean and 13.3% in women with ≥2 previous cesarean deliveries. The pooled performance of ultrasound for the antenatal detection of placenta previa accreta was higher in prospective than retrospective studies, with a diagnostic odds ratios of 228.5 (95% confidence interval, 67.2-776.9) and 80.8 (95% confidence interval, 13.0-501.4), respectively. Only 2 studies provided detailed data on the relationship between the depth of villous invasion and the number of previous cesarean deliveries, independently of the depth of the villous invasion. A cesarean hysterectomy was performed in 208 of 232 cases (89.7%) for which detailed data on management were available. Positive correlations were found in the largest prospective studies between the cumulative rates of the more invasive forms of accreta placentation and the sensitivity and specificity of ultrasound imaging but not with diagnostic odds ratio values. We found no data on the ultrasound screening of placenta accreta at the routine midtrimester ultrasound examination from the nonexpert ultrasound units.

CONCLUSION

Planning individual management for delivery is possible only with accurate evaluation of prenatal risk of accreta placentation in women presenting with a low-lying placenta/previa and a history of prior cesarean delivery. Ultrasound is highly sensitive and specific in the prenatal diagnosis of accreta placentation when performed by skilled operators. Developing a prenatal screening protocol is now essential to further improve the outcome of this increasingly more common major obstetric complication.

Maternal Morbidity in Women with Placenta Previa Managed with Prediction of Morbidly Adherent Placenta by Ultrasonography

Objective. To determine maternal morbidity in women with placenta previa managed with prediction of morbidly adherent placenta (MAP) by ultrasonography. Methods. A retrospective cohort study was undertaken comprising forty-one women who had placenta previa with or without risk factors for MAP. Women who had all three findings (bladder line interruption, placental lacunae, and absence of the retroplacental clear zone) were regarded as high suspicion for MAP and underwent cesarean section followed by hysterectomy. We attempted placental removal for women having two findings or less. Results. Among 28 women with risk, nine with high suspicion underwent hysterectomy and were diagnosed with MAP. Three of 19 women with two findings or less eventually underwent hysterectomy and were diagnosed with MAP. The sensitivity and positive predictive value for the detection of MAP were 64% and 100%. The pathological severity of MAP was significantly correlated with the cumulative number of findings. There were no cases of MAP among 13 women without risk. There was no difference of blood loss between women with high suspicion and those without risk (2186 ± 1438 ml versus 1656 ± 848 ml, resp.; p = 0.34). Conclusion. Management with prediction of MAP by ultrasonography is useful for obtaining permissible morbidity.

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.

Factors Contributing to Massive Blood Loss on Peripartum Hysterectomy for Abnormally Invasive Placenta: Who Bleeds More?

Introduction. To identify factors that determine blood loss during peripartum hysterectomy for abnormally invasive placenta (AIP-hysterectomy). Methods. We reviewed all of the medical charts of 11,919 deliveries in a single tertiary perinatal center. We examined characteristics of AIP-hysterectomy patients, with a single experienced obstetrician attending all AIP-hysterectomies and using the same technique. Results. AIP-hysterectomy was performed in 18 patients (0.15%: 18/11,919). Of the 18, 14 (78%) had a prior cesarean section (CS) history and the other 4 (22%) were primiparous women. Planned AIP-hysterectomy was performed in 12/18 (67%), with the remaining 6 (33%) undergoing emergent AIP-hysterectomy. Of the 6, 4 (4/6: 67%) patients were primiparous women. An intra-arterial balloon was inserted in 9/18 (50%). Women with the following three factors significantly bled less in AIP-hysterectomy than its counterpart: the employment of an intra-arterial balloon (4,448 ± 1,948 versus 8,861 ± 3,988 mL), planned hysterectomy (5,003 ± 2,057 versus 9,957 ± 4,485 mL), and prior CS (5,706 ± 2,727 versus 9,975 ± 5,532 mL). Patients with prior CS (-) bled more: this may be because these patients tended to undergo emergent surgery or attempted placental separation. Conclusion. Patients with intra-arterial balloon catheter insertion bled less on AIP-hysterectomy. Massive bleeding occurred in emergent AIP-hysterectomy without prior CS.

Placenta accreta spectrum: accreta, increta, and percreta

Placenta accreta can lead to hemorrhage, resulting in hysterectomy, blood transfusion, multiple organ failure, and death. Accreta has been increasing steadily in incidence owing to an increase in the cesarean delivery rate. Major risk factors are placenta previa in women with prior cesarean deliveries. Obstetric ultrasonography can be used to diagnose placenta accreta antenatally, which allows for scheduled delivery in a multidisciplinary center of excellence for accreta. Controversies exist regarding optimal management, including optimal timing of delivery, surgical approach, use of adjunctive measures, and conservative (uterine-sparing) therapy. We review the definition, risk factors, diagnosis, management, and controversies regarding placenta accreta.

Placental implantation abnormalities and risk of preterm delivery: a systematic review and metaanalysis

We sought to evaluate the extent of the association between placental implantation abnormalities (PIA) and preterm delivery in singleton gestations. We conducted a systematic review of English-language articles published from 1980 onward using PubMed, MEDLINE, EMBASE, CINAHL, LILACS, and Google Scholar, and by identifying studies cited in the references of published articles. Search terms were PIA defined as ≥ 1 of the following: placenta previa, placenta accreta, vasa previa, and velamentous cord insertion. Observational and experimental studies were included for review if data were available regarding any of the aforementioned PIA and regarding gestational age at delivery or preterm delivery. Case reports and case series were excluded. Studies were reviewed and data extracted. The primary outcome was gestational age at delivery or preterm delivery <37 weeks' gestation. Secondary outcomes included birthweight, 1- and 5-minute Apgar scores, neonatal intensive care unit (NICU) admission, neonatal and perinatal death, and small for gestational age. Of the 1421 studies identified, 79 met the defined criteria; 56 studies were descriptive and 23 were comparative. Based on the descriptive studies, the preterm delivery rates for low-lying/marginal placenta, placenta previa, placenta accreta, vasa previa, and velamentous cord insertion were 26.9%, 43.5%, 57.7%, 81.9%, and 37.5%, respectively. Based on the comparative studies using controls, there was decreased pregnancy duration for every PIA; more specifically, there was an increased risk for preterm delivery in patients with placenta previa (risk ratio [RR], 5.32; 95% confidence interval [CI], 4.39-6.45), vasa previa (RR, 3.36; 95% CI, 2.76-4.09), and velamentous cord insertion (RR, 1.95; 95% CI, 1.67-2.28). Risks of NICU admissions (RR, 4.09; 95% CI, 2.80-5.97), neonatal death (RR, 5.44; 95% CI, 3.03-9.78), and perinatal death (RR, 3.01; 95% CI, 1.41-6.43) were higher with placenta previa. Perinatal risks were also higher in patients with vasa previa (perinatal death rate RR, 4.52; 95% CI, 2.77-7.39) and velamentous cord insertion (NICU admissions [RR, 1.76; 95% CI, 1.68-1.84], small for gestational age [RR, 1.69; 95% CI, 1.56-1.82], and perinatal death [RR, 2.15; 95% CI, 1.84-2.52]). In singleton gestations, there is a strong association between PIA and preterm delivery resulting in significant perinatal morbidity and mortality.

Placenta Accreta and Total Placenta Previa in the 19th Week of Pregnancy

Placentation disorders are the result of impaired embedding of the placenta in the endometrium. The prevalence of these disorders is estimated to be around 0.3 %. A history of previous prior uterine surgery (especially cesarean section and curettage) is the most common risk factor. Impaired placentation is differentiated into deep placental attachment; marginal, partial and total placenta previa; and placenta accreta, increta and percreta. Treatment depends on the severity of presentation and ranges from expectant management to emergency hysterectomy. In most cases, preterm termination of pregnancy is necessary. We report here on the case of a 39-year-old woman with placenta accreta and total placenta previa who underwent hysterectomy in the 19th week of pregnancy.