Diagnostic accuracy of ultrasound in detecting the severity of abnormally invasive placentation: a systematic review and meta-analysis.

Our objective was to elucidate the overall diagnostic accuracy of ultrasound in detecting the severity of abnormally invasive placentation (AIP). Medline, Embase, CINAHL and The Cochrane databases were searched. The ultrasound signs explored were: loss of hypoechoic (clear) zone in the placental-uterine interface, placental lacunae, bladder wall interruption, myometrial thinning, focal exophitic mass, placental lacunar flow, subplacental vascularity, and uterovesical hypervascularity. Twenty studies (3209 pregnancies) were included. Ultrasound had an overall good diagnostic accuracy in identifying the depth of placental invasion with sensitivities of 90.6%, 93.0%, 89.5%, and 81.2% for placenta accreta, increta, accreta/increta, and percreta, respectively; the corresponding specificities were 97.1%, 98.4%, 94.7%, and 98.9%. Placental lacunae had sensitivities of 74.8%, 88.6%, and 76.3% for the detection of placenta accreta, increta, and percreta, respectively. Sensitivity and specificity of loss of the clear zone in identifying placenta accreta were 74.9% and 92.0%, whereas the corresponding figures for placenta increta and percreta were 91.6% and 76.9%, and 88.1% and 71.1%. Lacunar flow had sensitivities of 81.2%, 84.3%, and 45.2% for the detection of placenta accreta, increta, and percreta respectively; the corresponding figures for specificity were 84.0%, 79.7%, and 75.3%. Sensitivity of uterovesical hypervascularity was low for the detection of placenta accreta (12.3%) but high for placenta increta (94.4%) and percreta (86.2%); the corresponding figures for specificity were 90.8%, 88.0% and 88.2%, respectively. Ultrasound has an overall good diagnostic accuracy in recognizing the depth and the topography of placental invasion.

Pagani G ，Cali G ，Acharya G ，Trisch IT ，Palacios-Jaraquemada J ，Familiari A ，Buca D ，Manzoli L ，Flacco ME ，Fanfani F ，Liberati M ，Scambia G ，D'antonio F ... -  《-》

Diagnostic accuracy of ultrasound in detecting the depth of invasion in women at risk of abnormally invasive placenta: A prospective longitudinal study.

The aim of this study was to assess the diagnostic accuracy of ultrasound in detecting the depth of abnormally invasive placenta in women at risk. Prospective longitudinal study including women with placenta previa and at least one prior cesarean delivery or uterine surgery. Depth of abnormally invasive placenta was defined as the degree of trophoblastic invasion through the myometrium and was assessed with histopathological analysis. The ultrasound signs explored were: loss of clear zone, placental lacunae, bladder wall interruption, uterovesical hypervascularity, and increased vascularity in the parametrial region. In all, 210 women were included in the analysis. When using at least one sign, ultrasound had an overall sensitivity of 100% (95% CI 96.5-100) and overall specificity of 61.9 (95% CI 51.9-71.2) for all types of abnormally invasive placenta. Using two ultrasound signs increased the diagnostic accuracy in terms of specificity (100%, 95% CI 96.5-100) but did not affect sensitivity. When stratifying the analysis according to the depth of placental invasion, using at least one sign had a sensitivity of 100% (95% CI 93.7-100) and 100% (95% CI 92.6-100) for placenta accreta/increta and percreta, respectively. Using three ultrasound signs improved the detection rate for placenta percreta with a sensitivity of 100% (95% CI 92.6-100) and a specificity of 77.2% (95% CI 69.9-83.4). Ultrasound has a high diagnostic accuracy in detecting the depth of placental invasion when applied to a population with specific risk factors for anomalies such as placenta previa and prior cesarean delivery or uterine surgery.

Cali G ，Forlani F ，Timor-Trisch I ，Palacios-Jaraquemada J ，Foti F ，Minneci G ，Flacco ME ，Manzoli L ，Familiari A ，Pagani G ，Scambia G ，D'Antonio F ... -  《-》

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

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. 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." 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. 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. 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.

Jauniaux E ，Collins SL ，Jurkovic D ，Burton GJ ... -  《-》

Diagnostic accuracy of magnetic resonance imaging in detecting the severity of abnormal invasive placenta: a systematic review and meta-analysis.

Accurate prenatal diagnosis of abnormally invasive placenta (AIP) is fundamental because it significantly reduces maternal morbidities. Medline, Embase, CINAHL and the Cochrane databases were searched. The primary aim of the present review was to elucidate the diagnostic accuracy of prenatal magnetic resonance imaging (MRI) in recognizing the severity of AIP, defined as the depth and topography of invasion. The secondary aim was to ascertain the strength of association between each MRI sign and the depth of placental invasion and to test their individual predictive accuracy in detecting such invasion. Inclusion criteria were studies on women who had prenatal MRI for ultrasound suspicion or the presence of clinical risk factors for AIP. Estimates of sensitivity, specificity, positive and negative likelihood ratios and diagnostic odds ratio were calculated using the hierarchical summary receiver characteristics curve model, and individual data random-effect logistic regression was used to calculate OR. Twenty studies (1080 pregnancies undergoing MRI mainly for the ultrasound suspicion of AIP) were included. MRI showed a sensitivity of 94.4% [95% confidence interval (CI) 15.8-99.9], 100% (95% CI 75.3-100) and 86.5% (95% CI 74.2-94.4) for detection of placenta accreta, increta and percreta, respectively; the corresponding values for specificity were 98.8% (95% CI 70.7-100), 97.3% (95% CI 93.3-99.3), 96.8% (95% CI 93.5-98.7). MRI identified 100% of cases with S1 and 100% of those with S2 invasion confirmed at surgery. Among the different MRI signs, intra-placental dark bands showed the best sensitivity for the detection of placenta accreta, increta and percreta; as well as abnormal intra-placental vascularity, uterine bulging was associated with a higher risk of increta and percreta, exophitic mass and bladder tenting with placenta percreta. Prenatal MRI has an excellent diagnostic accuracy in identifying the depth and the topography of placental invasion. However, these findings come mainly from studies in which MRI was performed as a secondary imaging tool in women already screened for AIP on ultrasound and might not reflect its actual diagnostic performance in detecting the severity of these disorders.

Familiari A ，Liberati M ，Lim P ，Pagani G ，Cali G ，Buca D ，Manzoli L ，Flacco ME ，Scambia G ，D'antonio F ... -  《-》

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

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

Jauniaux E ，Collins S ，Burton GJ 《-》