The application of three-dimensional color power Doppler ultrasound in the depiction of abnormal uteroplacental angioarchitecture in placenta previa percreta

Placenta Accreta Spectrum (PAS) Disorder: Ultrasound versus Magnetic Resonance Imaging

OBJECTIVE

PAS is one of the most dangerous conditions associated with pregnancy and remains undiagnosed before delivery in from half to two-thirds of cases. Correct prenatal diagnosis is essential to reduce the burden of maternal and fetal morbidity. The purpose of our study is to evaluate the accuracy of US and MRI in the diagnosis of PAS.

STUDY DESIGN

In this retrospective study, 104 patients with suspected placenta accreta were enrolled and had been investigated with US and MRI. They were divided into four groups: no PAS, accreta, increta, and percreta.

RESULTS

Compared to MRI, US results were higher in the diagnosis and in the identification of PAS severity (85% US vs. 80% MRI). For both methods, in the case of posterior placenta, there is greater difficulty in identifying the presence/absence of the disease (67% in both methods) and the severity level (61% US vs. 55% MRI).

CONCLUSION

US, properly implemented with the application of defined and standardized scores, can be superior to MRI and absolutely sufficient for the diagnosis of PAS, limiting the use of MRI to a few doubtful cases and to cases in which surgical planning is necessary.

Spatiotemporal heterogeneity of PPARγ expression in porcine uteroplacenta for regulating of placental angiogenesis through VEGF-mediated signalling

Non-infectious prenatal mortality severely affects the porcine industry, with pathological placentation as a likely key reason. Previous studies have demonstrated that peroxisome proliferator-activated receptor gamma (PPARγ) deficiency causes defects in the uteroplacental vasculature and induces embryonic losses in mice. However, its role in porcine placental angiogenesis remains unclear. In the present study, PPARγ expression was investigated in porcine uteroplacental tissues at gestational day (GD) 25, GD40 and GD70 via quantitative polymerase chain reaction (qPCR), Western blot and immunohistochemistry (IHC). Moreover, the roles of PPARγ in porcine placental angiogenesis were investigated using a cell model of porcine umbilical vein endothelial cells (PUVECs) to conduct proliferation, migration and tube formation assays in vitro and a mouse xenograft model to assess capillary formation in vivo. The results showed that PPARγ was mainly located in the glandular epithelium, trophoblast, amniotic chorion epithelium and vascular endothelium, as indicated by the higher expression levels at GD25 and GD40 than at GD70 in endometrium and by higher expression levels at GD40 and GD70 than at GD25 in placenta. Moreover, PPARγ expression was significantly downregulated in placenta with dead foetus. In PUVECs, knocking out PPARγ significantly inhibited proliferation, migration and tube formation in vitro and inhibited capillary formation in mouse xenografts in vivo by blocking S-phase, promoting apoptosis and downregulating the angiogenic factors of VEGF and its receptors. Overall, the spatiotemporal heterogeneity of PPARγ expression in porcine uteroplacental tissue suggests its vital role in endometrial remodelling and placental angiogenesis, and PPARγ regulates placental angiogenesis through VEGF-mediated signalling.

Screening for morbidly adherent placenta in early pregnancy

OBJECTIVE

To estimate the diagnostic accuracy of a two-stage strategy for early prediction of morbidly adherent placenta (MAP). In the first stage, at 11-13 weeks' gestation, women with low-lying placenta and history of uterine surgery are classified as being at high risk for MAP and, in the second stage, at 12-16 weeks, these high-risk pregnancies are assessed at a specialist MAP clinic.

METHODS

This was a prospective study in women having an ultrasound scan at 11-13 weeks' gestation as a part of routine pregnancy care. Women with low-lying placenta and a history of uterine surgery were followed up at a specialist MAP clinic at 12-16 weeks' gestation, 20-24 weeks and 28-34 weeks. At each visit to the MAP clinic, an ultrasound scan was carried out and the following features suggestive of MAP were recorded: non-visible Cesarean section scar; bladder wall interruption; thin retroplacental myometrium; presence of intraplacental lacunar spaces; presence of retroplacental arterial-trophoblastic blood flow; and irregular placental vascularization demonstrated by three-dimensional power Doppler.

RESULTS

Screening at 11-13 weeks was carried out in 22 604 singleton pregnancies, 1298 (6%) of which were considered to be at high risk of MAP because they had previous uterine surgery and low-lying placenta. At the MAP clinic at 12-16 weeks, the diagnosis of MAP was suspected in 14 cases and this was confirmed at delivery in 13. In the rest of the population, there were no cases of MAP.

CONCLUSION

Accurate prediction of MAP can be achieved by ultrasound examination at 12-16 weeks' gestation. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tumorigenic factor CRIPTO-1 is immunolocalized in extravillous cytotrophoblast in placenta creta

CRIPTO-(CR)1 is a protein associated with tumorigenesis and metastasis. Here we demonstrate that CR-1 expression in normal and creta placentas is associated with various degrees of uterine invasion. Cytokeratin (CK) and CR-1 protein expression was visualized by immunohistochemical staining of formalin-fixed, paraffin-embedded placental specimens (control placentas, n = 9; accreta, n = 6; increta, n = 10; percreta, n = 15). The pattern of extravillous trophoblast (EVT) cell morphology was distinctive in creta placentas: densely-compacted cell columns and large star-shaped cells with a typically migratory phenotype, not common among third trimester control placentas. Quantification revealed higher CR-1 immunoreactivities in accreta (P = 0.001), increta (P = 0.0002), and percreta placentas (P = 0.001) than in controls. In contrast to controls, there was a significant positive relationship between CR-1 and CK reactivity in all creta placentas (accreta, P = 0.02; increta, P = 0.0001, and percreta, P = 0.025). This study demonstrated CR-1 expression in the placental bed, its increased expression in creta placentas, and EVT cells as the main CR-1-producing cell type. Morphological examination revealed an immature and invasive trophoblast profile in creta placentas, suggesting impairment of the trophoblast differentiation pathway. These findings provide important new insights into the pathophysiology of abnormal creta placentation and its gestational consequences.

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

Purpose

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

Material and Methods

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

Results

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

Conclusion

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

Imaging for acute pelvic pain in pregnancy

Acute pelvic pain in pregnancy presents diagnostic and therapeutic challenges. Standard imaging techniques need to be adapted to reduce harm to the foetus from X-rays because of their teratogenic and carcinogenic potential. Ultrasound remains the primary imaging investigation of the pregnant abdomen. Magnetic resonance imaging (MRI) has been shown to be useful in the diagnosis of gynaecological and obstetric problems during pregnancy and in the setting of acute abdomen during pregnancy. MRI overcomes some of the limitations of ultrasound, mainly the size of the gravid uterus. MRI poses theoretical risks to the foetus and care must be taken to minimise these with the avoidance of contrast agents. Teaching Points • Ultrasound and MRI are the preferred investigations for acute pelvic pain during pregnancy. • Ultrasound remains the primary imaging investigation because of availability and portability. • MRI helps differentiate causes of acute pelvic pain when ultrasound is inconclusive.

Comparing the diagnostic value of ultrasound and magnetic resonance imaging for placenta accreta: a systematic review and meta-analysis

The aim of this study was to evaluate the diagnostic value of ultrasound (US) as compared with magnetic resonance imaging (MRI) in the detection of placenta accreta. Sensitivity, specificity, summary receiver operating characteristic curves and areas under the curve (AUCs) were described and calculated using Meta-Disc Statistical Software, Version 1.4 (Unit of Clinical Biostatistics, Ramón y Cajal Hospital, Madrid, Spain). In the 13 studies included, US sensitivity was 83% (95% confidence interval [CI] 77%-88%), US specificity was 95% (95% CI: 93%-96%) and the diagnostic odds ratio (DOR) was 63.41 (95% CI: 29.04-138.48). In the MRI studies, sensitivity was 82% (95% CI: 72%-90%), specificity was 88% (95% CI: 81%-94%) and the DOR was 22.95 (95% CI: 3.19-165.11). Summary receiver operating characteristic analysis indicated that the diagnostic value of US in detection of placenta accreta is not significantly different from that of MRI. Both US and MRI were highly sensitive and specific in the detection of placenta accreta to support effective diagnostic methods.

Morbidly adherent placenta: evaluation of ultrasound diagnostic criteria and differentiation of placenta accreta from percreta

OBJECTIVES

To evaluate the diagnostic accuracy of two-dimensional (2D) gray-scale and color Doppler and three-dimensional (3D) power Doppler sonographic criteria for morbidly adherent placenta (MAP), and to identify criteria to help distinguish placenta accreta from placenta percreta.

METHODS

We enrolled 187 patients with placenta previa and history of uterine surgery and performed transabdominal and transvaginal ultrasound examination for early detection of MAP. With 2D gray-scale transabdominal and transvaginal ultrasonography, we investigated loss/irregularity of the echolucent area between the uterus and the placenta ('clear space'), thinning or interruption of the hyperechoic interface between the uterine serosa and the bladder wall and the presence of turbulent placental lacunae with high-velocity flow (>15 cm/s). Using transabdominal 3D power Doppler, we evaluated the hypervascularity of the uterine serosa-bladder wall interface and irregular intraplacental vascularization. Ultrasound findings were reviewed against the final diagnosis made during Cesarean section (CS).

RESULTS

MAP was detected on CS in 41 patients. All of them had an anterior placenta previa (34 major and seven minor) and had undergone at least one previous CS. The evaluated sonographic criteria showed good diagnostic performance; in MAP patients at least two out of five criteria were detected, with at most one of the criteria present in patients without MAP. Loss/irregularity of clear space used as a single criterion was responsible for the most false positives, demonstrating a low positive predictive value. Irregular intraplacental vascularization with tortuous confluent vessels affecting the entire width of the placenta, and hypervascularity of the entire uterine serosa-bladder wall interface, were only detected, on 3D power Doppler, in cases of placenta percreta.

CONCLUSIONS

The reviewed ultrasound criteria may be useful for the prenatal diagnosis of MAP and to differentiate between placenta accreta and placenta percreta; 3D power Doppler techniques were an important aid in the diagnosis.

Metastasis associated lung adenocarcinoma transcript 1 is up-regulated in placenta previa increta/percreta and strongly associated with trophoblast-like cell invasion in vitro

Placenta previa increta/percreta (I/P) is a severe form of invasive placentation associated with massive peripartum hemorrhage, which often requires Cesarean hysterectomy. The pathogenesis of invasive placentation is multidimensional, involving decidual deficiency, endomyometrial damage and excessively deep trophoblast invasion into the uterus. In this study, annealing control primer-polymerase chain reaction (ACP-PCR) was used to identify differentially expressed genes, which may impair placentation resulting in placenta previa I/P. Placental tissues from I/P and non-increta/percreta (non-I/P) sites were concomitantly collected from patients undergoing Cesarean hysterectomy. After ACP-PCR experiments (three patients), the differentially expressed bands, consistently showing up- or down-regulated trends between each of the I/P and non-I/P tissue pairs, were cloned and sequenced. Human non-protein coding metastasis associated lung adenocarcinoma transcript 1 (MALAT-1) gene was identified. Real-time quantitative PCR (10 patients) confirmed significant overexpression of MALAT-1 in I/P samples (P = 0.005). To investigate the role of MALAT-1 gene in the regulation of trophoblast cell invasion, targeting of MALAT-1 mRNA expression with short interfering RNA (siRNA) in trophoblast-like BeWo, JAR and JEG-3 choriocarcinoma cells was performed. The invasion ability of these cells was significantly suppressed after siRNA silencing (P < 0.001), and this was not correlated with abnormal MMP-2 and MMP-9 enzyme activities. Our results suggest that MALAT-1 expression in placenta previa I/P is increased and its down-regulation inhibits trophoblast-like cell invasion in vitro. MALAT-1 might be involved in regulating trophoblast invasion during the development of advanced invasive placentation.

Placental morphologic and functional imaging in high-risk pregnancies

The placenta is vital for fetal growth and development. Improvement in ultrasound and magnetic resonance imaging have improved our understanding of placental morphology that can be important as in the case of placental accrete/percreta. Functional imaging is presently mainly performed by the use of Doppler ultrasound and can give information on placental perfusion, which can be vital for clinical diagnosis. This review summarizes the present knowledge on placental imaging and it's clinical value in high-risk pregnancies.

Role of three-dimensional power Doppler in the antenatal diagnosis of placenta accreta: comparison with gray-scale and color Doppler techniques

OBJECTIVE

To assess the role of three-dimensional (3D) power Doppler in the antenatal diagnosis of placenta accreta and compare its diagnostic performance with gray-scale and color Doppler ultrasonography.

METHODS

One hundred and seventy pregnant women with persistent placenta previa totalis (after 28 weeks' gestation) were prospectively enrolled into this study. Gray-scale transabdominal ultrasound examination was performed to detect loss of the subendometrial echolucent zone and other abnormalities suggestive of placenta accreta. Color flow mapping was used to scan the whole placenta to detect any newly formed vessels at the serosa-bladder border or the presence of abnormal lacunae. Finally a targeted examination of angioarchitecture in the basal and lateral views of the placenta was carried out using 3D power Doppler. The ultrasound findings were analyzed with reference to the final diagnosis made during Cesarean delivery.

RESULTS

Placenta accreta and its variants (including increta and percreta) were confirmed in 39 patients at the time of Cesarean delivery. Based on receiver-operating characteristics analysis, 'numerous coherent vessels' visualized using 3D power Doppler in the basal view was the best single criterion for the diagnosis of placenta accreta, with a sensitivity of 97% and a specificity of 92%. If we considered the presence of at least one criterion to be diagnostic when using each ultrasound technique, then 3D power Doppler would have the best positive predictive value (76%), followed by gray-scale (51%) and color Doppler (47%). The majority of patients with placenta accreta showed multiple characteristic features on ultrasound imaging. In contrast, those patients with a false-positive diagnosis (i.e. the final diagnosis was placenta previa alone) tended to show isolated ultrasound markers of the condition.

CONCLUSION

3D power Doppler may be useful as a complementary technique for the antenatal diagnosis or exclusion of placenta accreta.

Antenatal diagnosis of placenta accreta: a review

The incidence of placenta accreta should rise steadily over the next century as the frequency of Cesarean sections and advanced maternal age, both independent risk factors, increases. Patients who are at risk should be identified before an ultrasound examination and the characteristic findings searched for. In the first trimester, these include a low-lying sac that appears to be attached to the anterior wall of the uterus. As early as 16 weeks irregular vascular sinuses appear, which have turbulent flow within. The bladder wall may appear interrupted or have small bulges of the placenta into the bladder space. Absence of the normal echolucent space between the placenta and myometrium is not a reliable sign by itself, since this space may be absent in normal patients with an anterior placenta. Color Doppler will show that some of the placental sinuses traverse the uterine wall. Magnetic resonance imaging has not yet been shown to aid in the diagnosis, but in the future, with improvement of resolution and shortened sequences, it should be particularly useful in identifying the patients that have placenta percreta.

Quantitative three-dimensional power Doppler ultrasound predicts the outcome of placental chorioangioma

The relationship of large and vascularized chorioangiomas to adverse pregnancy outcome is well recognized. We present a patient with a large placental tumor and signs of impending fetal cardiac failure. The angioarchitecture of the tumor depicted by three-dimensional (3D) power Doppler ultrasound enabled us to accurately diagnose a placental chorioangioma. During the follow-up period, quantitative flow data obtained using 3D power Doppler indicated altered hemodynamics in the tumor and concomitant improvement in the condition of the fetus, enabling us to manage the mother conservatively. Spontaneous delivery occurred at 38 weeks without any complications. This report demonstrates the potential value of 3D power Doppler in prenatal diagnosis and monitoring of pregnancies complicated by large, vascularized chorioangioma.