Impact of placenta previa with placenta accreta spectrum disorder on fetal growth

Research design and tissue collection considerations for investigation of placenta accreta spectrum

Placenta accreta spectrum (PAS) is a group of pregnancy pathologies characterized by loss/absence of decidua and trophoblast over-invasion penetrating into the myometrium beyond the normal depth. It is associated with expansion of deeper branches of the uterine arteries and placental adherence to the uterus. Undetected PAS leads frequently to massive and potentially fatal hemorrhage at delivery. For the more severe forms of PAS (increta, percreta), the most frequent solution is caesarean delivery-hysterectomy. The etiology of PAS is, however, unclear at best. While there is increasing research interest, the clinical intricacies of this pathology pose significant challenges for the researcher. In this communication we present the elements which we believe should be considered when undertaking (or interpreting) research into PAS, particularly when biological samples and molecular techniques are involved.

The Management of Placenta Accreta Spectrum Disorder

This chapter provides insight into current management strategies for the placenta accreta spectrum (PAS). PAS is one of the most morbid conditions of pregnancy, with significant maternal hemorrhage and surgical morbidity risks, and its increasing incidence. Here, we review the available data to help guide the clinical management of PAS, from time of diagnosis through delivery and postpartum care, while acknowledging the many areas of continued uncertainty. The evidence is strong for the importance of team-based, patient-centered, and multidisciplinary care for patients with PAS. However, much else remains uncertain and is predominantly guided by expert opinion. Ultimately, we aim to provide a current understanding of available literature and to emphasize that continued research is paramount to explore management and surgical approaches to move toward optimization of patient outcomes, including the patient experience.

Biology and Pathophysiology of Placenta Accreta Spectrum Disorder

Placenta accreta spectrum (PAS) disorders present a significant clinical challenge, characterized by abnormal placental adherence to the uterine wall secondary to uterine scarring. With the rising global cesarean delivery rates, the incidence of this iatrogenic disorder has increased, underscoring the critical need for an understanding of its pathophysiology to inform management and prevention strategies. Normal placentation depends on tightly regulated extravillous trophoblast invasion into the decidua, spiral artery remodeling, interactions with the extracellular matrix, and immune modulation. Uterine scarring disrupts this balance, creating an environment deficient in key regulatory signals required for coordinated implantation and decidualization. In PAS, the loss of inhibitory decidual cues and deficient boundary limits permits unrestrained trophoblast into the abnormal decidual environment. Dysregulated signaling, along with an inflammatory milieu in scarred tissues, exacerbates abnormal placental development. Current prenatal imaging focuses on the appearance of excessive fibrinoid deposition, extracellular matrix remodeling, and incomplete spiral artery transformation as surrogates of PAS risk stratification. Emerging single-cell RNA sequencing and proteomic profiling offer insights into biomarkers and pathways that enable targeted interventions. Preventive efforts should prioritize reducing cesarean delivery rates to limit uterine scarring. Advances in regenerative medicine and bioengineering, including extracellular matrix-modulating biomaterials, growth factor therapies, and antifibrotic interventions, hold promise for improving scar healing and reducing PAS risk. This review bridges foundational science and clinical application, emphasizing the importance of the underlying placental biology and pathophysiology to make a clinical difference in detecting, treating, and preventing PAS. Addressing drivers of abnormal placentation is critical for improving maternal and neonatal outcomes with this increasingly prevalent iatrogenic condition.

Evaluation of fetal growth and birth weight in pregnancies with placenta previa with and without placenta accreta spectrum

OBJECTIVES

We evaluated fetal growth and birthweight in pregnancies with placenta previa with and without placenta accreta spectrum (PAS).

METHODS

We retrospectively studied pregnant patients with placenta previa with or without PAS diagnosed at 20-37 weeks' gestation. Estimated fetal weight (EFW) percentile and fetal growth rate were calculated based on ultrasound at two timepoints: 20-24 and 30-34-weeks' gestation. Fetuses were small (SGA) or large for gestational age (LGA) when EFW or abdominal circumference was <10th or >90th percentile for gestational age, respectively. Fetal growth rate was estimated by subtracting EFW percentiles from the two ultrasounds. Birthweight in grams and percentiles were estimated via Anderson and INTERGROWTH-21 standards adjusted for neonatal sex. EFW percentiles, fetal growth rate, birth weight and birthweight percentiles were compared between patients with placenta previa with and without PAS.

RESULTS

We studied 171 patients with and 146 patients without PAS. SGA rates did not differ between groups on first (PAS n=3, no-PAS n=3, p=0.8) or second ultrasound (PAS n=10, no-PAS n=8, p=0.8). LGA rates were similar between groups on first (PAS n=11, no-PAS n=9, p=0.8) and second ultrasound (PAS n=20, no-PAS n=12, p=0.6). The growth rate was higher in fetuses with PAS than placenta previa (1.22 ± 22.3 vs. -4.1 ± 18.1, p=0.07), but not significantly. The birthweight percentile was higher in the PAS than the placenta previa group (74 vs. 67, p=0.01). On multi-linear regression, birthweight percentile remained higher in the PAS group, but not significantly.

CONCLUSIONS

Placenta previa with or without PAS is not associated with SGA, LGA or lower birthweight.

PAS or Not PAS? The Sonographic Assessment of Placenta Accreta Spectrum Disorders and the Clinical Validation of a New Diagnostic and Prognostic Scoring System

This study aimed to evaluate our center's experience in diagnosing and managing placenta accreta spectrum (PAS) in a high-risk population, focusing on prenatal ultrasound features associated with PAS severity and maternal outcomes. We conducted a retrospective analysis of 102 high-risk patients with confirmed placenta previa who delivered at our center between 2018 and 2023. Patients underwent transabdominal and transvaginal ultrasound scans, assessing typical sonographic features. Binary and multivariate logistic regression analyses were performed to identify sonographic markers predictive of PAS and relative complications. Key ultrasound features-retroplacental myometrial thinning (<1 mm), vascular lacunae, and retroplacental vascularization-were significantly associated with PAS and a higher risk of surgical complications. An exceedingly rare sign, the "riddled cervix" sign, was observed in only three patients with extensive cervical or parametrial involvement. Those patients had the worst surgical outcomes. This study highlights the utility of specific ultrasound features in stratifying PAS risk and guiding clinical and surgical management in high-risk pregnancies. The findings support integrating these markers into prenatal diagnostic protocols to improve patient outcomes and inform surgical planning.

Evaluation of maternal serum protein biomarkers in the prenatal evaluation of placenta accreta spectrum: A systematic scoping review

INTRODUCTION

Placenta accreta spectrum (PAS) is an increasingly commonly reported condition due to the continuous increase in the rate of cesarean deliveries (CD) worldwide; however, the prenatal screening for pregnant patients at risk of PAS at birth remains limited, in particular when imaging expertise is not available.

MATERIAL AND METHODS

Two major electronic databases (MEDLINE and Embase) were searched electronically for articles published in English between October 1992 and January 2023 using combinations of the relevant medical subject heading terms and keywords. Two independent reviewers selected observational studies that provided data on one or more measurement of maternal blood-specific biomarker(s) during pregnancies with PAS at birth. PRISMA Extension for Scoping Review (PRISMA-ScR) was used to extract data and report results.

RESULTS

Of the 441 reviewed articles, 29 met the inclusion criteria reporting on 34 different biomarkers. 14 studies were retrospective and 15 prospective overall including 18 251 participants. Six studies had a cohort design and the remaining a case-control design. Wide clinical heterogeneity was found in the included studies. In eight studies, the samples were obtained in the first trimester; in five, the samples were collected on hospital admission for delivery; and in the rest, the samples were collected during the second and/or third trimester.

CONCLUSIONS

Measurements of serum biomarkers, some of which have been or are still used in screening for other pregnancy complications, could contribute to the prenatal evaluation of patients at risk of PAS at delivery; however, important evidence gaps were identified for suitable cutoffs for most biomarkers, variability of gestational age at sampling and the potential overlap of the marker values with other placental-related complications of pregnancy.

The Association and diagnostic value between Maternal Serum Placental Markers and Placenta Previa

Objective

This study aims to evaluate the correlation and diagnostic value of maternal serum placental markers: pregnancy-associated plasma protein-A (PAPP-A), free beta human chorionic gonadotropin (free β-hCG), and alpha fetoprotein (AFP) in relation to placenta previa.

Methods

A retrospective case-control study was conducted to gather data on 137 pregnant women who were hospitalized for delivery at Hangzhou Women's Hospital. These women participated in the late stage of early and mid-term maternal serum prenatal screening between January 2018 and December 2020. Of the 137 women, 45 were diagnosed with placenta previa, while 92 were selected at random as the control group, in a ratio of 1: 2. Independent samples t-test or Mann-Whitney U test were utilized to compare the quantitative data of the two groups, and the Receiver operating characteristic curve (ROC) was used to evaluate the diagnostic value of maternal serum placental marker levels for placenta previa.

Results

The levels of first trimester and second trimester free beta subunit of human chorionic gonadotropin (FT-Free β-hCG; ST-Free β-hCG) in the placenta previa group were higher than those in the normal group [1.38 (0.55-6.03) MoM vs.1.08 (0.32-4.00) MoM, 1.38 (0.39-4.10) MoM vs.1.01 (0.29-4.12) MoM], and the differences between the groups were statistically significant (Z = 2.830, Z = 2.846, both P < 0.05). The AFP level was higher than the normal group [1.13 (0.65-2.15) MoM vs. 0.94 (0.51-2.02) MoM], and the difference was statistically significant (Z = 2.551, P < 0.05). There was no significant difference in PAPP-A between the placenta previa group and the normal group (Z = 1.396, P > 0.05). The ROC curve analysis results showed that the AUCs of FT-Free β-hCG and ST-Free β-hCG for placenta previa were 0.649 (95 % CI: 0.551-0.747, P = 0.005), 0.634 (95 % CI: 0.539-0.730, P = 0.011), and 0.650 (95 % CI: 0.554-0.746, P = 0.004). Using PPV, NPV, FPR, FNR, +LR, and -LR as evaluation indicators for the 5 models, the results showed that FT-Free β-hCG was the best performer in terms of PPV, FPR, and +LR, with values of 0.725, 0.600, and 2.632, respectively. The three-indicator combined detection model (AFP + ST-Free β-hCG + FT-Free β-hCG) had the best performance in terms of NPV and -LR, with values of 0.770 and 0.298, respectively.

Conclusion

The elevated maternal serum levels of Free β-hCG and AFP may be associated with placenta previa. The combined detection of maternal serum markers in the early and mid-trimesters has better diagnostic value for predicting placenta previa than individual detection.

Assessment of serum levels and placental bed tissue expression of IGF-1, bFGF, and PLGF in patients with placenta previa complicated with placenta accreta spectrum disorders

OBJECTIVE

This study aims to detect the serum levels of IGF-1, bFGF, and PLGF and their expressions in placental bed tissues of patients with placenta previa complicated with PAS disorders.

METHODS

This case and control study included 40 multiparous pregnant women with complete placenta previa between 34 weeks and 38 weeks of gestation and they were divided into two groups: 25 patients with PAS (case group) and 15 patients without PAS (control group). The venous blood samples were collected 2 h before the cesarean section, and the placental bed tissues were taken intraoperatively at the placental implantation site and then were histologically examined to evaluate the gravity of the myometrial invasion of the placenta. According to FIGO PAS increasing grading, the 25 patients were also divided into three groups: PAS grade I group, PAS grade II group, and PAS grade III group. The concentrations of IGF-1, bFGF, and PLGF in serum were measured using ELISA, and the mean ratio of the relative mRNA expression of each biomarker in placental bed tissues was calculated using qRT-PCR. The staining intensity and the positive cells were quantitatively measured and expressed as means by using Image J software for IHC analysis.

RESULTS

IGF-1 had low serum levels and high placental bed expression in placenta previa patients with PAS disorders compared to those without PAS (all p < 0.0001). PLGF had high serum levels (p = 0.0200) and high placental bed expression (p < 0.0001) in placenta previa patients with PAS disorders compared to those without PAS. IGF-1 serum levels decreased up to PAS grade II (means were 24.3 ± 4.03, 21.98 ± 3.29, and 22.03 ± 7.31, respectively for PAS grade I, PAS grade II, PAS grade III groups, p = 0.0006). PLGF serum levels increased up to PAS grade II (means were 12.96 ± 2.74, 14.97 ± 2.56, and 14.89 ± 2.14, respectively for the three groups, p = 0.0392). However, IGF-1 and PLGF mRNA placental bed expression increased up to PAS grade III. The relative expression of mRNA means for the three groups was 3.194 ± 1.40, 3.509 ± 0.63, and 3.872 ± 0.70, respectively for IGF-1; and 2.784 ± 1.14, 2.810 ± 0.71, and 2.869 ± 0.48, respectively for PLGF (all p < 0.0001). Their IHC (immunohistochemical) staining also had increasing trends, but p > 0.05. bFGF was not significantly expressed in placenta previa with PAS disorders in most of the analysis sections (p > 0.05).

CONCLUSIONS

Low serum levels and high expression in placental bed tissues of IGF-1, or high serum levels and high expression in placental bed tissues of PLGF, may differentiate placenta previa patients with FIGO PAS grade I and PAS grade II from those without PAS disorders. However, they could not significantly predict the degree of placental invasiveness in FIGO PAS grades II and III.

Neonatal outcomes in pregnancies complicated by placenta accreta- a matched cohort study

PURPOSE

Pregnancies complicated by placenta accreta spectrum (PAS) are associated with severe maternal morbidities. The aim of this study is to describe the neonatal outcomes in pregnancies complicated with PAS compared with pregnancies not complicated by PAS.

METHODS

A retrospective cohort study conducted at a single tertiary center between 03/2011 and 01/2022, comparing women with PAS who underwent cesarean delivery (CD) to a matched control group of women without PAS who underwent CD. We evaluated the following adverse neonatal outcomes: umbilical artery pH < 7.0, umbilical artery base excess ≤ - 12, APGAR score < 7 at 5 min, neonatal intensive care unit (NICU) admission, mechanical ventilation, hypoxic ischemic encephalopathy, seizures and neonatal death. We also evaluated a composite adverse neonatal outcome, defined as the occurrence of at least one of the adverse neonatal outcomes described above. Multivariable regression analysis was used to determine which adverse neonatal outcome were independently associated with the presence of PAS.

RESULTS

265 women with PAS were included in the study group and were matched to 1382 controls. In the PAS group compared with controls, the rate of composite adverse neonatal outcomes was significantly higher (33.6% vs. 18.7%, respectively, p < 0.001). In a multivariable logistic regression analysis, Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

CONCLUSION

Neonates in PAS pregnancies had higher rates of adverse outcomes. Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

Neonatal outcomes in the surgical management of placenta accreta spectrum disorders: a retrospective single-center observational study from 468 Vietnamese pregnancies beyond 28 weeks of gestation

BACKGROUND

Placenta accreta spectrum disorders (PASDs) increase the mortality rate for mothers and newborns over a decade. Thus, the purpose of the study is to evaluate the neonatal outcomes in emergency cesarean section (CS) and planned surgery as well as in Cesarean hysterectomy and the modified one-step conservative uterine surgery (MOSCUS). The secondary aim is to reveal the factors relating to poor neonatal outcomes.

METHODS

This was a single-center retrospective study conducted between 2019 and 2020 at Tu Du Hospital, in the southern region of Vietnam. A total of 497 pregnant women involved in PASDs beyond 28 weeks of gestation were enrolled. The clinical outcomes concerning gestational age, birth weight, APGAR score, neonatal intervention, neonatal intensive care unit (NICU) admission, and NICU length of stay (LOS) were compared between emergency and planned surgery, between the Cesarean hysterectomy and the MOSCUS. The univariate and multivariable logistic regression were used to assess the adverse neonatal outcomes.

RESULTS

Among 468 intraoperatively diagnosed PASD cases who underwent CS under general anesthesia, neonatal outcomes in the emergency CS (n = 65) were significantly poorer than in planned delivery (n = 403). Emergency CS increased the odds ratio (OR) for earlier gestational age, lower birthweight, lower APGAR score at 5 min, higher rate of neonatal intervention, NICU admission, and longer NICU LOS ≥ 7 days with OR, 95% confidence interval (CI) were 10.743 (5.675-20.338), 3.823 (2.197-6.651), 5.215 (2.277-11.942), 2.256 (1.318-3.861), 2.177 (1.262-3.756), 3.613 (2.052-6.363), and 2.298 (1.140-4.630), respectively, p < 0.05. Conversely, there was no statistically significant difference between the neonatal outcomes in Cesarean hysterectomy (n = 79) and the MOSCUS method (n = 217). Using the multivariable logistic regression, factors independently associated with the 5-min-APGAR score of less than 7 points were time duration from the skin incision to fetal delivery (min) and gestational age (week). One minute-decreased time duration from skin incision to fetal delivery contributed to reduce the risk of adverse neonatal outcome by 2.2% with adjusted OR, 95% CI: 0.978 (0.962-0.993), p = 0.006. Meanwhile, one week-decreased gestational age increased approximately two fold odds of the adverse neonatal outcome with adjusted OR, 95% CI: 1.983 (1.600-2.456), p < 0.0001.

CONCLUSIONS

Among pregnancies with PASDs, the neonatal outcomes are worse in the emergency group compared to planned group of cesarean section. Additionally, the neonatal comorbidities in the conservative surgery using the MOSCUS method are similar to Cesarean hysterectomy. Time duration from the skin incision to fetal delivery and gestational age may be considered in PASD surgery. Further data is required to strengthen these findings.

Placenta accreta spectrum disorder at single-cell resolution: a loss of boundary limits in the decidua and endothelium

BACKGROUND

Placenta accreta spectrum disorders are associated with severe maternal morbidity and mortality. Placenta accreta spectrum disorders involve excessive adherence of the placenta preventing separation at birth. Traditionally, this condition has been attributed to excessive trophoblast invasion; however, an alternative view is a fundamental defect in decidual biology.

OBJECTIVE

This study aimed to gain insights into the understanding of placenta accreta spectrum disorder by using single-cell and spatially resolved transcriptomics to characterize cellular heterogeneity at the maternal-fetal interface in placenta accreta spectrum disorders.

STUDY DESIGN

To assess cellular heterogeneity and the function of cell types, single-cell RNA sequencing and spatially resolved transcriptomics were used. A total of 12 placentas were included, 6 placentas with placenta accreta spectrum disorder and 6 controls. For each placenta with placenta accreta spectrum disorder, multiple biopsies were taken at the following sites: placenta accreta spectrum adherent and nonadherent sites in the same placenta. Of note, 2 platforms were used to generate libraries: the 10× Chromium and NanoString GeoMX Digital Spatial Profiler for single-cell and spatially resolved transcriptomes, respectively. Differential gene expression analysis was performed using a suite of bioinformatic tools (Seurat and GeoMxTools R packages). Correction for multiple testing was performed using Clipper. In situ hybridization was performed with RNAscope, and immunohistochemistry was used to assess protein expression.

RESULTS

In creating a placenta accreta cell atlas, there were dramatic difference in the transcriptional profile by site of biopsy between placenta accreta spectrum and controls. Most of the differences were noted at the site of adherence; however, differences existed within the placenta between the adherent and nonadherent site of the same placenta in placenta accreta. Among all cell types, the endothelial-stromal populations exhibited the greatest difference in gene expression, driven by changes in collagen genes, namely collagen type III alpha 1 chain (COL3A1), growth factors, epidermal growth factor-like protein 6 (EGFL6), and hepatocyte growth factor (HGF), and angiogenesis-related genes, namely delta-like noncanonical Notch ligand 1 (DLK1) and platelet endothelial cell adhesion molecule-1 (PECAM1). Intraplacental tropism (adherent versus non-adherent sites in the same placenta) was driven by differences in endothelial-stromal cells with notable differences in bone morphogenic protein 5 (BMP5) and osteopontin (SPP1) in the adherent vs nonadherent site of placenta accreta spectrum.

CONCLUSION

Placenta accreta spectrum disorders were characterized at single-cell resolution to gain insight into the pathophysiology of the disease. An atlas of the placenta at single cell resolution in accreta allows for understanding in the biology of the intimate maternal and fetal interaction. The contributions of stromal and endothelial cells were demonstrated through alterations in the extracellular matrix, growth factors, and angiogenesis. Transcriptional and protein changes in the stroma of placenta accreta spectrum shift the etiologic explanation away from "invasive trophoblast" to "loss of boundary limits" in the decidua. Gene targets identified in this study may be used to refine diagnostic assays in early pregnancy, track disease progression over time, and inform therapeutic discoveries.

Accuracy of Ultrasound in the Prediction of the FIGO Classification of Placenta Accreta Spectrum

OBJECTIVES

To evaluate the accuracy of greyscale ultrasound (US) and colour Doppler detecting placenta accreta spectrum (PAS) based on the newly recommended International Federation of Obstetrics and Gynaecology (FIGO) grading system.

METHODS

This prospective study was conducted on women diagnosed with placenta previa or low-lying placenta involving the anterior uterine wall and associated with PAS as identified by the US. Transabdominal and transvaginal greyscale US was performed on admission between 34 and 36 weeks of gestation and compared to clinical grading and histopathological examination after cesarean hysterectomy.

RESULTS

In total, 36 pregnant females who underwent a cesarean hysterectomy due to placenta previa complicated by PAS were included in this study. All patients had a history of previous cesarean deliveries, ranging from 1 to 5 deliveries. The US has an overall sensitivity of 33%, 55%, and 84.62%, and specificity of 100%, 75%, and 60% in detecting the 3 degrees of PAS, respectively. US cannot differentiate between the different subtypes of PAS grade 3 (a, b, and c).

CONCLUSION

The overall US evaluation was highly significant in predicting the FIGO diagnosis of PAS; however, all ultrasonographic signs were equally relevant in diagnosing grade 1 and/or 2 PAS and were inaccurate in differing the subtypes of PAS grade 3.

Placental lakes vs lacunae: spot the differences

Sonographic sonolucencies are anechoic areas surrounded by tissue of normal echogenicity, commonly found in the placental parenchyma during the second and third trimesters of pregnancy. The ultrasound appearance of lakes and lacunae derives from the low echogenicity of villous-free areas within the placental parenchyma, filled with maternal blood of varying velocities. In normal placentation, lakes usually start appearing as soon as maternal blood begins to flow freely within the intervillous space at the end of the first trimester, whereas, in accreta placentation, lacunae develop progressively during the second trimester. Larger lakes are found mainly in areas of lower villous density under the fetal plate or in the marginal areas, but can also be found in the center of a lobule above the entry of a spiral artery. Lakes of variable size, position and shape are of no clinical significance, except if they transform into echogenic cystic lesions, which have been associated with poor fetal growth and placental malperfusion. Lacunae are formed by the distortion of one or more placental lobules developing inside a uterine scar, resulting from high-volume, high-velocity flows from the radial/arcuate arteries, and are associated with a high probability of placenta accreta spectrum at birth. They often present with ultrasound signs of uterine remodeling following scarring. Lakes and lacunae can coexist within the same placenta and both will change in size and shape as pregnancy advances. Better understanding of the etiopathology of placental sonolucent spaces and associated morphological changes is necessary to identify patients at risk of subsequent complications during pregnancy and/or at delivery. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Placenta accreta spectrum ultrasound stage and fetal growth

OBJECTIVE

to evaluate fetal growth in pregnancies complicated by placenta accreta spectrum (PAS) and to compare fetal growth between cases stratified by ultrasound stage of PAS.

METHODS

This was a prospective multicenter cohort study of women diagnosed with PAS between January 2018 and December 2021. We grouped participants into cases by ultrasound stage (PAS stage 1-3) and controls (PAS0). Fetal growth centiles at three timepoints with median gestational ages of 21 ± 1 weeks (interquartile range [IQR], 20 ± 1-22 ± 0 weeks), 28 ± 0 weeks (IQR, 27 ± 0-28 ± 5 weeks), and 33 ± 0 weeks (IQR, 32 ± 1-34 ± 0 weeks) and birth weight centiles were compared between cases and controls and between those with PAS stratified by ultrasound stage.

RESULTS

A total of 53 women met inclusion criteria, with a mean age of 37 years (standard deviation, ±4.0 years) and body mass index of 27 kg/m² (standard deviation, ±5.8 kg/m² ). Median (IQR) fetal weight centiles were around the 50th centile at each timepoint, with no difference between groups. The incidence of small for gestational age (birth weight ≤ 10th percentile) and large for gestational age (birth weight ≥ 90th percentile) was 11.3% (n = 6) and 15.1% (n = 8), respectively, with no differences by ultrasound stage. The median birth weight centile was 64 (IQR, 26-85), with no differences between cases and controls or by ultrasound stage.

CONCLUSIONS

In our cohort, a diagnosis of PAS was not associated with fetal growth restriction.

The Association between Placenta Accreta Spectrum Severity and Incidence of Small for Gestational Age Neonates

OBJECTIVE

The aim of the study is to evaluate whether pathologic severity of placenta accreta spectrum (PAS) is correlated with the incidence of small for gestational age (SGA) and neonatal birthweight.

STUDY DESIGN

This was a multicenter cohort study of viable, non-anomalous, singleton gestations delivered with histology-proven PAS. Data including maternal history, neonatal birthweight, and placental pathology were collected and deidentified. Pathology was defined as accreta, increta, or percreta. The primary outcome was rate of SGA defined by birth weight less than the 10th percentile. The secondary outcomes included incidence of large for gestational age (LGA) babies as defined by birth weight greater than the 90th percentile as well as incidence of SGA and LGA in preterm and term gestations. Statistical analysis was performed using Chi-square, Kruskal-Wallis, and log-binomial regression. Increta and percreta patients were each compared with accreta patients.

RESULTS

Among the cohort of 1,008 women from seven United States centers, 865 subjects were included in the analysis. The relative risk (RR) of SGA for increta and percreta did not differ from accreta after adjusting for confounders (adjusted RR = 0.63, 95% confidence interval [CI]: 0.36-1.10 for increta and aRR = 0.72, 95% CI: 0.45-1.16 for percreta). The results were stratified by placenta previa status, which did not affect results. There was no difference in incidence of LGA (p = 1.0) by PAS pathologic severity. The incidence of SGA for all PAS patients was 9.2% for those delivered preterm and 18.7% for those delivered at term (p = 0.004). The incidence of LGA for all PAS patients was 12.6% for those delivered preterm and 13.2% for those delivered at term (p = 0.8203).

CONCLUSION

There was no difference in incidence of SGA or LGA when comparing accreta to increta or percreta patients regardless of previa status. Although we cannot suggest causation, our results suggest that PAS, regardless of pathologic severity, is not associated with pathologic fetal growth in the preterm period.

KEY POINTS

· PAS severity is not associated with SGA in the preterm period.. · PAS severity is not associated with LGA.. · Placenta previa does not affect the incidence of SGA in women with PAS..

Risk of preterm birth for placenta previa or low-lying placenta and possible preventive interventions: A systematic review and meta-analysis

Objective

To investigate the risk of preterm birth in women with a placenta previa or a low-lying placenta for different cut-offs of gestational age and to evaluate preventive interventions.

Search and methods

MEDLINE, EMBASE, CENTRAL, Web of Science, WHO-ICTRP and clinicaltrials.gov were searched until December 2021. Randomized controlled trials, cohort studies and case-control studies assessing preterm birth in women with placenta previa or low-lying placenta with a placental edge within 2 cm of the internal os in the second or third trimester were eligible for inclusion. Pooled proportions and odds ratios for the risk of preterm birth before 37, 34, 32 and 28 weeks of gestation were calculated. Additionally, the results of the evaluation of preventive interventions for preterm birth in these women are described.

Results

In total, 34 studies were included, 24 reporting on preterm birth and 9 on preventive interventions. The pooled proportions were 46% (95% CI [39 - 53%]), 17% (95% CI [11 - 25%]), 10% (95% CI [7 - 13%]) and 2% (95% CI [1 - 3%]), regarding preterm birth <37, <34, <32 and <28 weeks in women with placenta previa. For low-lying placentas the risk of preterm birth was 30% (95% CI [19 - 43%]) and 1% (95% CI [0 - 6%]) before 37 and 34 weeks, respectively. Women with a placenta previa were more likely to have a preterm birth compared to women with a low-lying placenta or women without a placenta previa for all gestational ages. The studies about preventive interventions all showed potential prolongation of pregnancy with the use of intramuscular progesterone, intramuscular progesterone + cerclage or pessary.

Conclusions

Both women with a placenta previa and a low-lying placenta have an increased risk of preterm birth. This increased risk is consistent across all severities of preterm birth between 28-37 weeks of gestation. Women with placenta previa have a higher risk of preterm birth than women with a low-lying placenta have. Cervical cerclage, pessary and intramuscular progesterone all might have benefit for both women with placenta previa and low-lying placenta, but data in this population are lacking and inconsistent, so that solid conclusions about their effectiveness cannot be drawn.

Systematic review registration

PROSPERO https://www.crd.york.ac.uk/prospero/, identifier CRD42019123675.

Prospective comparative analysis for application and selection of FIESTA sequence and SSFSE sequence in MRI for prenatal diagnosis of placenta previa accreta

Placenta previa accreta patients were examined using fast-imaging employing steady-state acquisition (FIESTA) and single-shot fast spin echo (SSFSE) sequence. The diagnostic value of the two sequences was compared. FIESTA was better than the SSFSE sequence in displaying outline-boundary (excellent: 82 vs. 26), signal-to-noise ratio (excellent: 75 vs. 54) for placenta and uterus. The direct signs detection rate in FIESTA was higher than SSFSE (implantable: P = .028, adhesive: P = .131, penetrating type: P = .326). The indirect signs detection rate in FIESTA was lower than SSFSE (low-signal density: P = .029, uneven-signal density: P = .328, thicker and more vascular shadow: P = 398). FIESTA combining SSFSE demonstrated higher detecting rates (100% for sensitivity, specificity, and accuracy) for all types than single sequence scanning (FIESTA/SSFSE). In conclusion, FIESTA clearly showed the situation of the placenta and uterus in placenta previa accreta patients, with excellent image quality. A combination of FIESTA and SSFSE can improve the diagnostic value of placenta previa accreta.Important statementWhat is already known on this subject? Placenta previa is the most common cause of vaginal bleeding in the third trimester of pregnancy.What do the results of this study add? FIESTA was better than the SSFSE sequence in displaying images and demonstrated higher detection rates for direct signs and lower detection rate comparing the SSFSE sequence. FIESTA combining SSFSE sequence demonstrated higher detecting rates for implantable, adhesive and penetrating types than single sequence scanning.What are the implications of these findings for clinical practice and/or further research? FIESTA sequence clearly showed the situation of placenta and uterus in placenta previa accreta patients, with excellent image quality. Combination of FIESTA and SSFSE sequences can effectively improve the diagnostic value of placenta previa accreta.

Maternal Smoking and the Risk of Placenta Accreta Spectrum: A Systematic Review and Meta-Analysis

Background

This is the first meta-analysis that assessed the association between maternal smoking and the risk of placenta accreta spectrum (PAS), so this study was aimed at investigating the association between maternal smoking and PAS based on observational studies. PAS is defined as a severe obstetric complication due to the abnormal invasion of the chorionic villi into the myometrium and uterine serosa.

Methods

We searched electronic bibliographic databases including PubMed, Web of Science, Scopus, Science Direct, and Google Scholar until January 2022. The results were reported using a random effect model. The chi-square test and the I² statistic were used to assess heterogeneity. Egger's and Begg's tests were used to examine the probability of publication bias. All statistical analyses were performed at a significance level of 0.05 using Stata software, version 11.

Results

Based on the random effect model, the estimated OR of the risk of PAS associated with smoking was 1.21 (95% CI: 1.02, 1.41; I² = 4.7%). Subgroup analysis was conducted based on study design, and the result showed that the association between smoking and PAS among cohort studies was significant 1.35 (95% CI: 1.15, 1.55; I² = 0.0%).

Conclusion

Our results suggested that maternal smoking is a risk factor for the PAS. There was no heterogeneity among studies that reported an association between smoking and the PAS. The Newcastle-Ottawa Scale (NOS) was used to measure study quality.

Risk Factors and Pregnancy Outcome in Women with a History of Cesarean Section Complicated by Placenta Accreta

Objective

To explore the risk factors and pregnancy outcomes in women with a history of cesarean section complicated by placenta accreta (PA).

Methods

This case-control study included clinical data from singleton mothers with a history of cesarean section in 11 public tertiary hospitals in seven provinces of China between January 2017 and December 2017. According to the intraoperative findings after delivery, the study population was divided into PA and non-PA groups. We compared the pregnancy outcomes between the two groups, used multivariate logistic regression to analyze the risk factors for placental accreta.

Results

For this study we included 11,074 pregnant women with a history of cesarean section; and of these, 869 cases were in the PA group and 10,205 cases were in the non-PA group. Compared with the non-PA group, the probability of postpartum hemorrhage (236/10,205, 2.31% vs. 283/869, 32.57%), severe postpartum hemorrhage (89/10,205, 0.87% vs. 186/869, 21.75%), diffuse intravascular coagulation (3/10,205, 0.03% vs. 4/869, 0.46%), puerperal infection (33/10,205, 0.32% vs. 12/869, 1.38%), intraoperative bladder injury (1/10,205, 0.01% vs. 16/869, 1.84%), hysterectomy (130/10,205, 1.27% vs. 59/869, 6.79%), and blood transfusion (328/10,205,3.21% vs. 231/869,26.58%) was significantly increased in the PA group (P < 0.05). At the same time, the neonatal birth weight (3250.00 (2950.00-3520.00) g vs. 2920.00 (2530.00-3250.00) g), the probability of neonatal comorbidities (245/10,205, 2.40% vs. 61/869, 7.02%), and the rate of neonatal intensive care unit admission (817/10,205, 8.01% vs. 210/869, 24.17%) also increased significantly (P < 0.05). Weight (odds ratio (OR) = 1.03, 95% confidence interval (CI): 1.01-1.05)), parity (OR = 1.18, 95%CI: 1.03-1.34), number of miscarriages (OR = 1.31, 95%CI: 1.17-1.47), number of previous cesarean sections (OR = 2.57, 95%CI: 2.02-3.26), history of premature rupture of membrane (OR = 1.61, 95%CI: 1.32-1.96), previous cesarean-section transverse incisions (OR = 1.38, 95%CI: 1.12-1.69), history of placenta previa (OR = 2.44,95%CI: 1.50-3.96), and the combination of prenatal hemorrhage (OR = 9.95,95%CI: 8.42-11.75) and placenta previa (OR = 91.74, 95%CI: 74.11-113.56) were all independent risk factors for PA.

Conclusion

There was an increased risk of adverse outcomes in pregnancies complicated by PA in women with a history of cesarean section, and this required close clinical attention. Weight before pregnancy, parity, number of miscarriages, number of previous cesarean sections, history of premature rupture of membranes, past transverse incisions in cesarean sections, a history of placenta previa, prenatal hemorrhage, and placenta previa were independent risk factors for pregnancies complicated with PA in women with a history of cesarean section. These independent risk factors showed a high value in predicting the risk for placentab accreta in pregnancies of women with a history of cesarean section.

New insights into the etiopathology of placenta accreta spectrum

Placenta accreta has been described as a spectrum of abnormal attachment of villous tissue to the uterine wall, ranging from superficial attachment to the inner myometrium without interposing decidua to transmural invasion through the entire uterine wall and beyond. These descriptions have prevailed for more than 50 years and form the basis for the diagnosis and grading of accreta placentation. Accreta placentation is essentially the consequence of uterine remodeling after surgery, primarily after cesarean delivery. Large cesarean scar defects in the lower uterine segment are associated with failure of normal decidualization and loss of the subdecidual myometrium. These changes allow the placental anchoring villi to implant, and extravillous trophoblast cells to migrate, close to the serosal surface of the uterus. These microscopic features are central to the misconception that the accreta placental villous tissue is excessively invasive and have led to much confusion and heterogeneity in clinical data. Progressive recruitment of large arteries in the uterine wall, that is, helicine, arcuate, and/or radial arteries, results in high-velocity maternal blood entering the intervillous space from the first trimester of pregnancy and subsequent formation of placental lacunae. Recently, guided sampling of accreta areas at delivery has enabled accurate correlation of prenatal imaging data with intraoperative features and histopathologic findings. In more than 70% of samples, there were thick fibrinoid depositions between the tip of most anchoring villi and the underlying uterine wall and around all deeply implanted villi. The distortion of the uteroplacental interface by these dense depositions and the loss of the normal plane of separation are the main factors leading to abnormal placental attachment. These data challenged the classical concept that placenta accreta is simply owing to villous tissue sitting atop the superficial myometrium without interposed decidua. Moreover, there is no evidence in accreta placentation that the extravillous trophoblast is abnormally invasive or that villous tissue can cross the uterine serosa into the pelvis. It is the size of the scar defect, the amount of placental tissue developing inside the scar, and the residual myometrial thickness in the scar area that determine the distance between the placental basal plate and the uterine serosa and thus the risk of accreta placentation.

USMRI Features and Clinical Data-Based Model for Predicting the Degree of Placenta Accreta Spectrum Disorders and Developing Prediction Models

AIM

This study aimed to investigate the ability of ultrasound/magnetic resonance imaging (MRI) signature and clinical data-based model for preoperatively predicting the degree of placenta accreta spectrum disorders and develop combined prediction models.

METHODS

The clinicopathological characteristics, prenatal ultrasound images, and MRI features of 132 pregnant women with placenta accreta spectrum disorders at Xiangyang No. 1 People's Hospital were retrospectively reviewed from January 2016 to December 2020. In the training set of 99 patients, the ultrasound/MRI features model, clinical characteristics model, and combined model were developed by multivariate logistic regression analysis to predict the degree of placenta accreta spectrum disorders. The prediction performance of different models was compared using the Delong test. The developed models were validated by assessing their prediction performance in a test set of 33 patients.

RESULTS

The multivariate logistic regression analysis identified history of abortion, history of endometrial injury, and blurred boundary between the placenta and the myometrium/between the uterine serosa and the bladder to construct a combined model for predicting the degree of placenta accreta spectrum disorders (area under the curve (AUC) = 0.931; 95% confidence interval (CI): 0.882-0.980). The AUC of the clinical characteristics model and ultrasound/MRI features model was 0.858 (95% CI 0.794-0.921) and 0.709 (95% CI 0.624-0.798), respectively. The AUC of the combined model was significantly higher than that of the ultrasound/MRI features model (P < 0.001) or clinical characteristics model (P < 0.0015) in the training set. In the test set, the combined model also showed higher prediction performance.

CONCLUSIONS

Ultrasound/MRI-based signature is a powerful predictor for the degree of placenta accreta spectrum disorders in an early stage. A combined model (constructed with history of abortion, history of endometrial injury, and blurred boundary between the placenta and the myometrium/between the uterine serosa and the bladder) can improve the accuracy for predicting the degree of placenta accreta spectrum disorders in an early stage.

Placenta Accreta Spectrum: In Vitro Fertilization and Non-In Vitro Fertilization and Placenta Accreta Spectrum in a Massachusetts Cohort

OBJECTIVE

The incidence of placenta accreta spectrum (PAS) has been increasing in the United States. In addition, there has also been an increase in the utilization of in vitro fertilization (IVF). The IVF pregnancies confer an increased risk of adverse obstetric and neonatal outcomes, but there is limited data on whether IVF is associated with PAS. The aim of this study is to assess the association between IVF and the risk of PAS.

STUDY DESIGN

This was a retrospective cohort study of deliveries from January 1, 2013 to August 1, 2018 at a tertiary hospital in the Massachusetts. IVF pregnancies were compared with non-IVF pregnancies, and PAS diagnosis was confirmed by histopathology reports. Hospital administrative data and medical record review were used, and supplemented with data from birth certificates from the Massachusetts Department of Public Health.

RESULTS

We identified 28,344 pregnancies that met inclusion criteria, of which 1,418 (5.0%) were IVF pregnancies. The overall incidence of PAS was 0.4% (2.2% in the IVF group and 0.3% in the non-IVF group). Women who underwent IVF had 5.5 times the risk of PAS (95% confidence interval [CI]: 3.4-8.7) compared with women in the non-IVF group, adjusted for maternal age, nulliparity, and year of delivery (Table 5). Compared with women in the non-IVF group, the IVF group had fewer prior cesarean deliveries (22.6 vs. 64.2%) and a lower prevalence of placenta previa (19.4 vs. 44.4%).

CONCLUSION

Women with an IVF pregnancy carry an increased risk of PAS compared with non-IVF. Among women who underwent IVF, there was a lower prevalence of prior cesarean deliveries and placenta previa. Future work is needed to identify the mechanism of association for this increased risk as well as a reliable tool for antenatal detection in this cohort of women.

KEY POINTS

· IVF pregnancies have higher risk of PAS than non-IVF pregnancies.. · IVF pregnancies with PAS do not exhibit common risk factors.. · IVF may be an independent risk factor for PAS..

Clinical value of serum VEGF and sFlt-1 in pernicious placenta previa

This study was designed to explore the expression and the diagnostic value of vascular endothelial growth factor (VEGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) in pernicious placenta previa (PPP) combined placental accreta/increta. A total of 140 PPP patients were enrolled and divided into two groups: 56 patients with placenta accreta/increta (PA group), and 84 patients without placenta accreta/increta (non-PA group). In the same period, 46 pregnant women without PPP who had undergone caesarean section were selected as controls. The levels of VEGF and sFlt-1 in serum were detected by enzyme-linked immunosorbent assay. Diagnostic efficiency of VEGF and sFlt-1 in serum were evaluated by receiver operating characteristics curve. It was found that both VEGF and sFlt-1 had diagnostic value for PPP and placenta accreta/increta combined PPP. In addition, the levels of VEGF and sFlt-1 could be used to distinguish placenta accreta from placenta increta. VEGF was negatively correlated with sFlt-1 in PPP patients. In summary, the levels of VEGF and sFlt-1 could be used as auxiliary indicators to diagnose PPP and distinguish between placenta accreta and increta.KEY POINTSThe levels of VEGF and sFlt-1 could be used to distinguish placenta accreta from placenta increta.VEGF is negatively correlated with sFlt-1 in PPP patients.The levels of VEGF and sFlt-1 could be used as auxiliary indicators to diagnose PPP and distinguish between placenta accreta and increta.

The clinical value of prenatal assessment of cervical length and placental thickness in pregnant women with placenta previa

OBJECTIVE

This study was designed to investigate the clinical value of prenatal assessment of cervical length (CL) and placental thickness (PT) in pregnancy outcome and prognosis of pregnant women with placenta previa.

METHODS

Eighty pregnant women with placenta previa treated in our hospital were enrolled for prenatal assessment of CL and PT, and were grouped as CL ≤ 30 mm (n=32) and CL > 30 mm (n=48) groups and PT ≥ 10 mm (n=34) and PT < 10 mm (n=46) groups, respectively. The pregnancy and perinatal outcomes were compared in different groups. ROC curve of CL and PT on preterm delivery was drawn, and the diagnostic value of CL and PT in diagnosing preterm delivery was calculated.

RESULTS

The pregnancy and perinatal outcomes of CL ≤ 30 mm group were significantly inferior to those of CL > 30 mm group (P < 0.05). The pregnancy and perinatal outcomes of PT ≥ 10 mm group were also significantly inferior to those of PT < 10 mm group (P < 0.05). PT and CL had good predictive values for preterm delivery (P < 0.05), with high diagnostic sensitivity, specificity and accuracy.

CONCLUSION

Prenatal assessment of CL and PT has practical clinical significance for pregnant women with placenta previa, which helps in assessing pregnancy and perinatal outcomes and is worthy of clinical application.

Placenta praevia - does it really affect intrauterine fetal growth?

PURPOSE

Placenta praevia affects about 0.5% of pregnancies and due to constant increase in operative deliveries may become an important, clinical challenge throughout the next decades. Location of the placental plate within lower uterine segment is associated with increased risk of adverse perinatal outcomes. There were several reports pointing increased risk of small-for-gestational-age (SGA)/fetal growth restriction (FGR) in patients affected with abnormal location of the placenta. On the other hand, some studies ended up with opposite conclusions.

MATERIALS AND METHODS

Due to ambiguous results we have undertaken a case-control study to investigate intrauterine growth among this group. We ran a pilot study to precisely define maternal, obstetrical and neonatal characteristics in order to avoid cofounders. Our study incorporated 56 patients in singleton pregnancies affected with placenta praevia and 124 patients in the control group (between 35 and 37 weeks of gestation).

RESULTS

Nonetheless, there were no statistical differences in the birthweight between the study and control group (2882.5 g vs. 2805 g, p = ns). Moreover, rates of the newborns with birthweight corresponding <10th percentile and >90th did not differ significantly. Even further analysis that included parity did not reveal any differences between both groups.

CONCLUSION

Placenta praevia does not affect the intrauterine growth and shall not be considered as a risk factor for SGA/FGR. In patients affected with abnormal location of the placenta additional scans for fetal well-being assessment are not indicated.

Cesarean Scar Pregnancy Successfully Managed to Term: When the Patient Is Determined to Keep the Pregnancy

Cesarean scar pregnancy (CSP) is a rare form of ectopic pregnancy, defined as the implantation of the gestational sac at the uterine incision scar of the previous cesarean section. This condition is associated with severe maternal and fetal/neonatal complications, including severe bleeding, rupture of the uterus, fetal demise, or preterm delivery. In view of these, early diagnosis allows the option of termination of pregnancy. In this case report, we present a patient with a cesarean scar pregnancy who was diagnosed at the sixth week of gestation but declined early termination of the pregnancy and was managed to the 38th week. Placenta previa was confirmed in the second trimester. A planned cesarean section was performed that resulted in the birth of a live full-term neonate. Intraoperatively, placenta percreta was diagnosed, and due to uncontrollable bleeding, a hysterectomy was performed. The postoperative course was uneventful. In cases where an early diagnosis of CSP is made, women should be counseled that this will almost certainly evolve to placenta previa, and the associated risks should be explained. Close follow-up of CSP is mandatory if expectant management is selected. Further studies are needed for definitive conclusions and to determine the risks of expectant management.

Ultrasound-histopathologic features of the utero-placental interface in placenta accreta spectrum

INTRODUCTION

The objective of this study was to evaluate the relationship between utero-placental vascular changes on ultrasound imaging and histopathologic findings according to the grade of villous invasion in placenta accreta spectrum (PAS).

METHODS

The ultrasound features of 31 patients with singleton pregnancies diagnosed prenatally with low-lying/placenta previa accreta were compared with histopathology findings following caesarean hysterectomy (n = 25) or partial myometrial resection (n = 6). The number and degree of transformation of arteries within the superficial layer of myometrium were recorded. Cytokeratin 7 (CK7) immunohistochemistry was used to complement H&E analysis.

RESULTS

All 31 patients presented with loss of clear zone, myometrial thinning and placenta lacunae. Subplacental hypervascularity and lacunae feeder vessels were found in 25 and nine cases, respectively. Large recent intervillous thromboses were found in one case with adherent villi and 12 cases with invasive villi, and showed a significantly different distribution according to lacunae scores. Thick basal plate fibrinoid deposits were found in all the areas of abnormally adherent and invasive villous tissue There was no significant difference in the mean count of partially remodeled vessels or vessels completely lacking remodeling according to the lacunae score and grade of placental invasiveness. EVT cells were arranged in superficial confluent sheets or superficial irregular clusters, or were scattered deep below the basal plate.

CONCLUSION

Placental ultrasound and histopathologic features associated with PAS are more pronounced in invasive cases suggesting that they are secondary to the haemodynamic effects of abnormally deep placentation and transformation of the radial and arcuate arteries.

Effect of previous placenta previa on outcome of next pregnancy: a 10-year retrospective cohort study

BACKGROUND

To determine the effects of previous placenta previa on the maternal and neonatal outcomes of the next pregnancy.

METHODS

This 10-year retrospective cohort study was conducted in the Department of Obstetrics and Gynecology, Third Affiliated Hospital of Guangzhou Medical University, between January 2009 and 2018. We retrospectively analyzed the effects of a previous singleton pregnancy in women with and without placenta previa on the outcomes of the subsequent pregnancy. To control for confounders, we used multiple logistic regression models.

RESULTS

A total of 57,251 women with singleton pregnancies gave birth during the 10-year study period. Among them, 6070 women had two consecutive births. For the first pregnancy, 1603 women delivered by cesarean delivery and 4467 by vaginal delivery. Among women with a history of cesarean delivery, placenta previa was an independent risk factor for hemorrhage (adjusted odds ratio [aOR]: 2.25, 95% confidence interval [CI]: 1.1-4.62), placenta accreta spectrum (PAS) disorders (aOR: 4.11, 95% CI: 1.68-10.06), and placenta previa (aOR: 6.24, 95% CI: 2.85-13.67) during the subsequent pregnancy. Puerperal infection, blood transfusion, and perinatal outcomes did not significantly differ between women with a history of placenta previa and women without this history. Among women with a history of vaginal delivery, placenta previa increased the risk of PAS disorders (aOR: 5.71, 95% CI: 1.81-18.03) and placenta previa (aOR: 4.14, 95% CI: 1.07-16.04) during the subsequent pregnancy. There was no significant difference between the two groups in terms of hemorrhage, blood transfusion, puerperal infection, and perinatal outcomes.

CONCLUSIONS

Women with a history of placenta previa are at risk for adverse outcomes such as postpartum hemorrhage, PAS disorders, and placenta previa in the subsequent pregnancy.

Placental Implantation Disorders

Primary disorders of placental implantation have immediate consequences for the outcome of a pregnancy. These disorders have been known to clinical science for more than a century, but have been relatively rare. Recent epidemiologic obstetric data have indicated that the rise in their incidence over the last 2 decades has been iatrogenic in origin. In particular, the rising numbers of pregnancies resulting from in vitro fertilization (IVF) and the increased use of caesarean section for delivery have been associated with higher frequencies of previa implantation, accreta placentation, abnormal placental shapes, and velamentous cord insertion. These disorders often occur together.

Conservative Surgical Management of Placenta Accreta Spectrum: A Pragmatic Approach

In the last 30 years, with increasing cesarean section rates, the incidence of the placenta accreta spectrum has also increased. It is estimated that by the year 2020 there will be nearly 9000 cases annually in the United States. Currently, no consensus exists regarding optimal management. Conventional treatment by cesarean-hysterectomy is challenging, with a high maternal morbidity due to massive hemorrhage, and surgical complications such as urinary tract, bowel and pelvic nerve injury, in addition to loss of fertility and its accompanying psychological trauma. Innovative approaches seek to preserve the uterus with the adherent placenta in situ, thus maintaining fertility and potentially reducing hemorrhage and adjacent organ injury. This review reports strategies for conservative treatment of such conditions, based on the current literature.