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

A randomized controlled trial reducing cesarean delivery rates in China by introducing trial of labor after cesarean and electrohysterography

OBJECTIVE

A cesarean delivery (CD) can affect health of both mother and child and future pregnancies. Since the abandonment of the one-child policy in China, obstetricians tend to perform a repeat CD rather than a trial of labor after cesarean (TOLAC). This study aims to reduce CD rates by increasing vaginal births after cesarean (VBAC) rates and introducing electrohysterography (EHG) for accurate monitoring.

METHODS

In total, 82 women received counseling regarding TOLAC at the Shijiazhuang Sixth Hospital in China. Women opting for TOLAC were randomized for either external tocodynamometry (TOCO, i.e. standard care) or EHG. The primary outcome was the VBAC rate. Secondary outcomes were indications for CD, percentage of assisted vaginal deliveries, labor duration, maternal blood loss, complications and neonatal outcomes.

RESULTS

After accounting for preterm delivery and dropouts, all counseled women opted for a TOLAC (100%). After randomization, 42 women were included in the TOCO-group and 37 in the EHG-group. Women did not receive pain medication and labor was not augmented with oxytocin. The VBAC rate was 71.4% in the TOCO-group, versus 78.4% in the EHG-group (p = .48). Birth was assisted with forceps in 11.9% of TOCO-group versus 2.7% of EHG-group (p = .21). One secondary CD (i.e. a shift from intended vaginal delivery to surgical delivery within the same labor) was performed because of a suspicion of uterine rupture (TOCO-group). Other indications for CD were: fetal distress, labor dystocia, fetal position, cephalopelvic disproportion. There were no significant differences in secondary study outcomes. No complications were reported.

CONCLUSION

This study showed an average VBAC rate of 75%, without any complications, in a hospital with no previous experience with TOLAC. The VBAC rate with EHG-monitoring was higher than TOCO, although this difference was not significant. To demonstrate a significant difference, larger clinical studies are necessary.

TRIAL REGISTRATION

The Daily Board of the Medical Ethics Committee of The Maternal and Child Hospital of Shijiazhuang approved the study protocol (number 20171018, Dutch Trial Register NL8199).

Prenatal detection of placenta accreta spectrum using a sonographic checklist

INTRODUCTION

The European Working Group for Abnormally Invasive Placenta proposed a checklist of ultrasound features for the antenatal detection of placenta accreta spectrum (PAS). This study aims to assess the performance of the checklist in identifying histopathologically confirmed PAS cases in a cohort with a high pre-test probability of PAS, and identify if particular features are associated with PAS.

MATERIAL AND METHODS

This is a prospective multi-site cohort study conducted between 2018 and 2023. Consecutive patients who underwent ultrasound assessment for suspicion of PAS were included, and the sonographic checklist was completed at the time of ultrasound. Cases were defined as PAS where they had intraoperative findings as described by the International Federation of Gynecology and Obstetrics (FIGO) grading, and histopathological findings for hysterectomy and myometrial resection cases. All non-PAS cases in this study had placenta previa and at least one prior cesarean delivery.

RESULTS

Seventy-eight participants met inclusion criteria, of whom 63 (80.7%) were diagnosed with PAS. Cesarean hysterectomy was performed in 49 cases (62.8%). Overall, third-trimester ultrasound performed at a median gestational age of 32 weeks (IQR 30-34 weeks) had a sensitivity of 0.84 (95% CI 0.73 to 0.92) and specificity of 0.73 (95% CI 0.45 to 0.92) for detecting PAS, with a positive and negative likelihood ratio of 3.15 (95% CI 1.35 to 7.35) and 0.22 (95% CI 0.11 to 0.41), respectively. Features most associated with PAS were abnormal placental lacunae (Odds Ratio [OR] 5.40 [95% CI 1.61 to 18.03] and myometrial thinning OR 6.87 [95% CI 1.93 to 24.4]). While many of the ultrasound features seen in PAS were also present in cases of placenta previa with prior Cesarean section, the median (IQR) number of features present in PAS cases was significantly higher than in the non-PAS placenta previa group (six features [3-8] vs. two features [0-3] p = 0.001). No case of non-PAS placenta previa had more than five features present.

CONCLUSIONS

The use of a standardized sonographic checklist had a high sensitivity and good specificity for the detection of PAS in this prospective cohort of well-classified PAS cases.

Emergency delivery in pregnancies at high probability of placenta accreta spectrum on prenatal imaging: a systematic review and meta-analysis

BACKGROUND

Placenta accreta spectrum disorders are associated with a high risk of maternal morbidity, particularly when surgery is performed under emergency conditions. This study aimed to investigate the incidence of emergency cesarean delivery in patients with a high probability of placenta accreta spectrum disorders on prenatal imaging and to compare the maternal and neonatal outcomes between patients requiring emergency cesarean delivery and those not requiring emergency cesarean delivery.

DATA SOURCES

MEDLINE, Embase, Cochrane, and ClinicalTrials.gov databases were searched.

STUDY ELIGIBILITY CRITERIA

This study included case-control studies reporting the outcomes of pregnancies with a high probability of placenta accreta spectrum on prenatal imaging confirmed at birth delivered via unplanned emergency cesarean delivery vs those delivered via planned elective cesarean delivery for maternal or fetal indications. The outcomes observed were the occurrence of emergency cesarean delivery; incidence of placenta accreta and placenta increta/placenta percreta; preterm birth at <34 weeks of gestation; and indications for emergency delivery. This study analyzed and compared the outcomes between patients who underwent emergency cesarean delivery and those who underwent elective cesarean delivery, including estimated blood loss; number of packed red blood cell units transfused and blood products transfused; transfusion of more than 4 units of packed red blood cell; ureteral, bladder, or bowel injury; disseminated intravascular coagulation; relaparotomy after the primary surgery; maternal infection or fever; wound infection; vesicouterine or vesicovaginal fistula; admission to the neonatal intensive care unit; maternal death; composite neonatal morbidity; fetal or neonatal loss; Apgar score of <7 at 5 minutes; and neonatal birthweight.

METHODS

Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale for case-control and cohort studies. Random-effect meta-analyses of proportions, risks, and mean differences were used to combine the data.

RESULTS

A total of 11 studies with 1290 pregnancies complicated by placenta accreta spectrum were included in the systematic review. Emergency cesarean delivery was reported in 36.2% of pregnancies (95% confidence interval, 28.1-44.9) with placenta accreta spectrum at birth, of which 80.3% of cases (95% confidence interval, 36.5-100.0) occurred before 34 weeks of gestation. The main indication for emergency cesarean delivery was antepartum bleeding, which complicated 61.8% of the cases (95% confidence interval, 32.1-87.4). Patients who underwent emergent cesarean delivery had higher estimated blood loss during surgery (pooled mean difference, 595 mL; 95% confidence interval, 116.10-1073.90; P<.001), higher number of packed red blood cells transfused (pooled mean difference, 2.3 units; 95% confidence interval, 0.99-3.60; P<.001), and higher number of blood products transfused (pooled mean difference, 3.0; 95% confidence interval, 1.10-4.90; P=.002) than patients who underwent scheduled cesarean delivery. Patients who underwent emergency cesarean delivery had a higher risk of requiring transfusion of more than 4 units of packed red blood cell (odds ratio, 3.8; 95% confidence interval, 1.7-4.9; P=.002), bladder injury (odds ratio, 2.1; 95% confidence interval, 1.1-4.0; P=.003), disseminated intravascular coagulation (odds ratio, 6.1; 95% confidence interval, 3.1-13.1; P<.001), and admission to the intensive care unit (odds ratio, 2.1; 95% confidence interval, 1.4-3.3; P<.001). Newborns delivered via emergency cesarean delivery had a higher risk of adverse composite neonatal outcomes (odds ratio, 2.6; 95% confidence interval, 1.4-4.7; P=.019), admission to the neonatal intensive care unit (odds ratio, 2.5; 95% confidence interval, 1.1-5.6; P=.029), Apgar score of <7 at 5 minutes (odds ratio, 2.7; 95% confidence interval, 1.5-4.9; P=.002), and fetal or neonatal loss (odds ratio, 8.2; 95% confidence interval, 2.5-27.4; P<.001).

CONCLUSION

Emergency cesarean delivery complicates approximately 35% of pregnancies affected by placenta accreta spectrum disorders and is associated with a higher risk of adverse maternal and neonatal outcomes. Large prospective studies are needed to evaluate the clinical and imaging signs that can identify patients with a high probability of placenta accreta spectrum at birth, patients at risk of requiring emergency cesarean delivery or peripartum hysterectomy, and patients at high risk of experiencing intrapartum hemorrhage.

External validation of and improvement upon a model for the prediction of placenta accreta spectrum severity using prospectively collected multicenter ultrasound data

INTRODUCTION

This study aimed to validate the Sargent risk stratification algorithm for the prediction of placenta accreta spectrum (PAS) severity using data collected from multiple centers and using the multicenter data to improve the model.

MATERIAL AND METHODS

We conducted a multicenter analysis using data collected for the IS-PAS database. The Sargent model's effectiveness in distinguishing between abnormally adherent placenta (FIGO grade 1) and abnormally invasive placenta (FIGO grades 2 and 3) was evaluated. A new model was developed using multicenter data from the IS-PAS database.

RESULTS

The database included 315 cases of suspected PAS, of which 226 had fully documented standardized ultrasound signs. The final diagnosis was normal placentation in 5, abnormally adherent placenta/FIGO grade 1 in 43, and abnormally invasive placenta/FIGO grades 2 and 3 in 178. The external validation of the Sargent model revealed moderate predictive accuracy in a multicenter setting (C-index 0.68), compared to its higher accuracy in a single-center context (C-index 0.90). The newly developed model achieved a C-index of 0.74.

CONCLUSIONS

The study underscores the difficulty in developing universally applicable PAS prediction models. While models like that of Sargent et al. show promise, their reproducibility varies across settings, likely due to the interpretation of the ultrasound signs. The findings support the need for updating the current ultrasound descriptors and for the development of any new predictive models to use data collected by different operators in multiple clinical settings.

Shedding of Syncytiotrophoblast-Derived Extracellular Vesicles Is Increased in Placenta Previa and Accreta Spectrum

Placenta accreta spectrum (PAS) refers to excessive placental invasion into the maternal uterus and it is associated with high risk of obstetric haemorrhage and adverse maternal-neonatal outcomes. Currently, no specific circulating biomarkers of PAS have been identified. Given that in PAS disorders, the depth and the extension of placental invasion into the uterus are expected to be increased, in this study, we analysed plasma levels of syncytiotrophoblast-derived extracellular vesicles (STBEVs) in women with placenta previa (PP), at a high risk of PAS disorders, and pregnant women with normal placentation. Venous blood samples were collected from 35 women with ultrasonographic diagnosis of PP and 35 women with normal placentation, matched for gestational age. Plasma samples were ultracentrifuged at 120.000 g to collect extracellular vesicles (EVs). To identify and quantify plasma placenta-derived EVs (or STBEVs), EVs were analysed by flow cytometry using a monoclonal antibody against placental alkaline phosphatase (PLAP). Plasma levels of STBEVs were significantly higher in PP patients compared to controls. Plasma levels of STBEVs in women with PP and PAS showed a trend to a higher concentration compared to women with PP without PAS, although not reaching a statistical significance. Circulating STBEVs are potential candidates as biological markers to be integrated to ultrasonography in the antenatal screening programme for PAS. More studies are needed to confirm our observation in a larger cohort of patients and to analyse a possible association between high circulating levels of STBEVs and PAS.

Trimester-specific diagnostic accuracy of ultrasound for detection of placenta accreta spectrum: systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic accuracy of ultrasound for detecting placenta accreta spectrum (PAS) during the first trimester of pregnancy and compare it with the accuracy of second- and third-trimester ultrasound examination in pregnancies at risk for PAS.

METHODS

PubMed, EMBASE and Web of Science databases were searched to identify relevant studies published from inception until 10 March 2023. Inclusion criteria were cohort, case-control or cross-sectional studies that evaluated the accuracy of ultrasound examination performed at < 14 weeks of gestation (first trimester) or ≥ 14 weeks of gestation (second/third trimester) for the diagnosis of PAS in pregnancies with clinical risk factors. The primary outcome was the diagnostic accuracy of sonography in detecting PAS in the first trimester, compared with the accuracy of ultrasound examination in the second and third trimesters. The secondary outcome was the diagnostic accuracy of each sonographic marker individually across the trimesters of pregnancy. The reference standard was PAS confirmed at pathological or surgical examination. The potential of ultrasound and different ultrasound signs to detect PAS was assessed by computing summary estimates of sensitivity, specificity, diagnostic odds ratio and positive and negative likelihood ratios.

RESULTS

A total of 37 studies, including 5764 pregnancies at risk of PAS, with 1348 cases of confirmed PAS, were included in our analysis. The meta-analysis demonstrated that ultrasound had a sensitivity of 86% (95% CI, 78-92%) and specificity of 63% (95% CI, 55-70%) during the first trimester, and a sensitivity of 88% (95% CI, 84-91%) and specificity of 92% (95% CI, 85-96%) during the second/third trimester. Regarding sonographic markers examined in the first trimester, lower uterine hypervascularity exhibited the highest sensitivity (97% (95% CI, 19-100%)), and uterovesical interface irregularity demonstrated the highest specificity (99% (95% CI, 96-100%)). In the second/third trimester, loss of clear zone had the highest sensitivity (80% (95% CI, 72-86%)), and uterovesical interface irregularity exhibited the highest specificity (99% (95% CI, 97-100%)).

CONCLUSIONS

First-trimester ultrasound examination has similar accuracy to second- and third-trimester ultrasound examinations for the diagnosis of PAS. Routine first-trimester ultrasound screening for patients at high risk of PAS may improve detection rates and allow earlier referral to tertiary care centers for pregnancy management. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Modified one-step conservative uterine surgery (MOSCUS) versus cesarean hysterectomy in the management of placenta accreta spectrum: A single-center retrospective analysis based on 619 Vietnamese pregnant women

OBJECTIVES

To compare maternal outcome measures in surgical management of placenta accreta spectrum (PAS)-the modified one-step conservative uterine surgery (MOSCUS), a new approach at Tu Du Hospital in Vietnam, versus cesarean hysterectomy, and to identify factors that appear to contribute to the successful outcome of the MOSCUS.

METHODS

This retrospective study was conducted at Tu Du Hospital in southern Vietnam between January 2019 and December 2020. The study enrolled all pregnant women at more than 28 weeks of pregnancy with a diagnosis of PAS who underwent either a cesarean hysterectomy or a uterus-preserving approach using the MOSCUS method.

RESULTS

The prevalence of PAS at our single tertiary referral hospital was 0.4% (619 PAS cases/132 518 births) in 2 years. Among 296 patients, the surgical time duration, estimated blood loss, and red blood cell transfusion in the MOSCUS group (n = 217) were all significantly less than in the cesarean hysterectomy group (n = 79) (152.72 ± 42.23 vs 185.13 ± 58.22 min, 1000 vs 1500 mL, and 500 vs 710 mL, respectively). Intraoperatively, the rate of visceral injuries in the hysterectomy group was higher than that in the MOSCUS group (P < 0.001). However, the rate of postoperative infection was higher in the MOSCUS group than in the cesarean hysterectomy group (P = 0.012). Of a total of 217 cases managed using the MOSCUS management, 24 required a secondary hysterectomy; the success rate was 88.9% (95% confidence interval [CI] 84.3%-93.1%). Some of the primary factors associated with the success of MOSCUS included maternal age less than 35 years, planned surgery, severity of PAS, and estimated blood loss during surgery (odds ratio [OR] 5.16, 95% CI 1.96-13.59; OR 3.05, 95% CI 1.08-8.62; OR 3.62, 95% CI 1.19-10.98; and OR 49.66, 95% CI 11.16-221.02, respectively; P < 0.05).

CONCLUSION

MOSCUS is an acceptable alternative to cesarean hysterectomy in many patients diagnosed with PAS. This new surgical management of PAS resulted in the preservation of the uterus, and a favorable outcome in nearly 9 out of 10 pregnant women. We believe that MOSCUS can be safely offered for the management of PAS in referral hospital settings.

Serum exosomal microRNA pathway activation in placenta accreta spectrum: pathophysiology and detection

BACKGROUND

Placenta accreta spectrum disorders are a complex range of placental pathologies that are associated with significant maternal morbidity and mortality. A diagnosis of placenta accreta spectrum relies on ultrasonographic findings with modest positive predictive value. Exosomal microRNAs are small RNA molecules that reflect the cellular processes of the origin tissues.

OBJECTIVE

We aimed to explore exosomal microRNA expression to understand placenta accreta spectrum pathology and clinical use for placenta accreta spectrum detection.

STUDY DESIGN

This study was a biomarker analysis of prospectively collected samples at 2 academic institutions from 2011 to 2022. Plasma specimens were collected from patients with suspected placenta accreta spectrum, placenta previa, or repeat cesarean deliveries. Exosomes were quantified and characterized by nanoparticle tracking analysis and western blotting. MicroRNA were assessed by polymerase chain reaction array and targeted single quantification. MicroRNA pathway analysis was performed using the Ingenuity Pathway Analyses software. Placental biopsies were taken from all groups and analyzed by polymerase chain reaction and whole cell enzyme-linked immunosorbent assay. Receiver operating characteristic curve univariate analysis was performed for the use of microRNA in the prediction of placenta accreta spectrum. Clinically relevant outcomes were collected from abstracted medical records.

RESULTS

Plasma specimens were analyzed from a total of 120 subjects (60 placenta accreta spectrum, 30 placenta previa, and 30 control). Isolated plasma exosomes had a mean size of 71.5 nm and were 10 times greater in placenta accreta spectrum specimens (20 vs 2 particles/frame). Protein expression of exosomes was positive for intracellular adhesion molecule 1, flotilin, annexin, and CD9. MicroRNA analysis showed increased detection of 3 microRNAs (mir-92, -103, and -192) in patients with placenta accreta spectrum. Pathway interaction assessment revealed differential regulation of p53 signaling in placenta accreta spectrum and of erythroblastic oncogene B2 or human epidermal growth factor 2 in control specimens. These findings were subsequently confirmed in placental protein analysis. Placental microRNA paralleled plasma exosomal microRNA expression. Biomarker assessment of placenta accreta spectrum signature microRNA had an area under the receiver operating characteristic curve of 0.81 (P<.001; 95% confidence interval, 0.73-0.89) with a sensitivity and specificity of 89.2% and 80%, respectively.

CONCLUSION

In this large cohort, plasma exosomal microRNA assessment revealed differentially expressed pathways in placenta accreta spectrum, and these microRNAs are potential biomarkers for the detection of placenta accreta spectrum.

Determinants of emergency Cesarean delivery in pregnancies complicated by placenta previa with or without placenta accreta spectrum disorder: analysis of ADoPAD cohort

OBJECTIVES

To investigate the rate and outcome of emergency Cesarean delivery (CD) in women with placenta previa with or without placenta accreta spectrum disorders (PAS) and to elucidate the diagnostic accuracy of ultrasound in predicting emergency CD.

METHODS

This was a secondary analysis of a multicenter prospective study involving 16 referral hospitals in Italy (ADoPAD study). Inclusion criteria were women with placenta previa minor (< 20 mm from the internal cervical os) or placenta previa major (covering the os), aged ≥ 18 years, who underwent transabdominal and transvaginal ultrasound assessment at ≥ 26 + 0 weeks of gestation. The primary outcome was the occurrence of emergency CD, defined as the need for immediate surgical intervention performed for emergency maternal or fetal indication, including active labor, cumulative maternal bleeding > 500 mL, severe and persistent vaginal bleeding such that maternal hemodynamic stability could not be achieved or maintained, or category-III fetal heart rate tracing unresponsive to resuscitative measures. The primary outcome was reported separately in the population of women with placenta previa and no PAS confirmed after birth and in those with PAS. The secondary aim was to report on the strength of association and to test the diagnostic accuracy of ultrasound in predicting emergency CD. Univariate, multivariate and diagnostic accuracy analyses were used to analyze the data.

RESULTS

A total of 450 women, including 97 women with placenta previa and PAS and 353 with placenta previa only, were analyzed. In women with placenta previa and PAS, emergency CD was required in 20.6% (95% CI, 14-30%), and 60.0% (12/20) delivered before 34 weeks of gestation. The mean gestational age at delivery was 32.3 ± 2.7 weeks in women undergoing emergency CD and 34.9 ± 1.8 weeks in those undergoing elective CD (P < 0.001). Women undergoing emergency CD had a higher median estimated blood loss (2500 (interquartile range (IQR), 1350-4500) vs 1100 (IQR, 625-2500) mL; P = 0.012), mean units of blood transfused (7.3 ± 8.8 vs 2.5 ± 3.4; P = 0.02) and more frequent placement of a mechanical balloon (50.0% vs 16.9%; P = 0.002) compared with those undergoing elective CD. On univariate analysis, the presence of interrupted retroplacental space, interrupted bladder line and placental lacunae was more common in women not experiencing emergency CD. No comprehensive multivariate analysis could be performed in this subgroup of women. Ultrasound signs of PAS, including presence of interrupted retroplacental space, interrupted bladder line and placental lacunae, were not predictive of emergency CD. In women with placenta previa but no PAS, emergency CD was required in 31.2% (95% CI, 26.6-36.2%), and 32.7% (36/110) delivered before 34 weeks of gestation. The mean gestational age at delivery was lower in women undergoing emergency CD compared with those undergoing elective CD (34.2 ± 2.9 vs 36.7 ± 1.6 weeks; P < 0.001). Pregnancies complicated by emergency CD were associated with a lower birth weight (2330 ± 620 vs 2800 ± 480 g; P < 0.001) and had a higher risk of need for blood transfusion (22.7% vs 10.7%; P = 0.003) compared with those who underwent elective CD. On multivariate analysis, only placental thickness (odds ratio (OR), 1.02 (95% CI, 1.00-1.03); P = 0.046) and cervical length < 25 mm (OR, 3.89 (95% CI, 1.33-11.33); P = 0.01) were associated with emergency CD. However, a short cervical length showed low diagnostic accuracy for predicting emergency CD in these women.

CONCLUSION

Emergency CD occurred in about 20% of women with placenta previa and PAS and 30% of those with placenta previa only and was associated with worse maternal outcome compared with elective intervention. Prenatal ultrasound is not predictive of the risk of emergency CD in women with these disorders. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Cesarean section rate: navigating the gap between WHO recommended range and current obstetrical challenges

The cesarean section (CS) rate is very heterogeneous all over the world, reflecting the differences in the access to healthcare services. In higher-income countries, changes observed in the obstetrical population brought to an increased rate of cesarean section for maternal request. Besides, clinicians are facing an increasing number of induction of labor, with the consequent risk of CS if the management is inappropriate. Analyzing the rate of primary CS, the interpretation of intrapartum CTG and a tailored management of labor are also red flags that must be considered. In this optic, the implementation of obstetrics training and simulation programs and the improvement of clinical protocols with the latest evidence can lead to the reduction of unnecessary CS.

The prenatal diagnostic indicators of placenta accreta spectrum disorders

Placenta accreta spectrum (PAS) disorders refers to a heterogeneous group of anomalies distinguished by abnormal adhesion or invasion of chorionic villi through the myometrium and uterine serosa. PAS frequently results in life-threatening complications, including postpartum hemorrhage and hysterotomy. The incidence of PAS has increased recently as a result of rising cesarean section rates. Consequently, prenatal screening for PAS is essential. Despite the need to increase specificity, ultrasound is still considered a primary adjunct. Given the dangers and adverse effects of PAS, it is necessary to identify pertinent markers and validate indicators to improve prenatal diagnosis. This article summarizes the predictors regarding biomarkers, ultrasound indicators, and magnetic resonance imaging (MRI) features. In addition, we discuss the effectiveness of joint diagnosis and the most recent research on PAS. In particular, we focus on (a) posterior placental implantation and (b) accreta after in vitro fertilization-embryo transfer, both of which have low diagnostic rates. At last, we graphically display the prenatal diagnostic indicators and each diagnostic performance.

Placental and Umbilical Cord Anomalies Diagnosed by Two- and Three-Dimensional Ultrasound

The aim of this review is to present a wide spectrum of placental and umbilical cord pathologies affecting the pregnancy. Placental and umbilical cord anomalies are highly associated with high-risk pregnancies and may jeopardize fetal well-being in utero as well as causing a predisposition towards poor perinatal outcome with increased fetal and neonatal mortality and morbidity. The permanent, computerized perinatology databases of different international centers have been searched and investigated to fulfil the aim of this manuscript. An extended gallery of prenatal imaging with autopsy correlation in specific cases will help to provide readers with a useful iconographic tool and will assist with the understanding and definition of this critical obstetrical and perinatological issue.

An update of diagnostic efficacy of ultrasound and magnetic resonance imaging in the diagnosis of clinically significant placenta accreta spectrum disorders

PURPOSE OF REVIEW

Systematic screening and diagnosis of placenta accreta spectrum disorder (PAS) either by ultrasound or magnetic resonance imaging (MRI) would allow referral of high-risk women to specialized multidisciplinary teams. We aimed to report recent findings regarding the diagnostic accuracy of ultrasound and magnetic resonance imaging in the diagnosis of PAS.

RECENT FINDINGS

Recent evidence from the literature shows that both ultrasound and MRI are good tests to identify PAS in high-risk populations. Ultrasound can also be used safely to guide management decisions, concentrating greater resources in patients with the higher risk of clinically significant PAS requiring complex peripartum management. Moreover, there are increasing data showing that routine contingent screening for PAS disorders based on the finding of a placenta implanted low in the uterine cavity and previous uterine surgery is effective in a public healthcare setting. A contingent screening strategy for PAS is feasible if placental location is routinely assessed during routine scans, and may even start from the first trimester of pregnancy.

SUMMARY

Ultrasound is an effective tool to screen pregnancies at high risk of PAS. In such pregnancies, ultrasound and MRI are effective imaging modalities for guiding management.