Placenta Accreta: Spectrum of US and MR Imaging Findings

Department of Radiology and Obstetrics, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH 44109, USA.
Radiographics (Impact Factor: 2.6). 11/2008; 28(7):1905-16. DOI: 10.1148/rg.287085060
Source: PubMed


Placenta accreta (PA) encompasses various types of abnormal placentation in which chorionic villi attach directly to or invade the myometrium. PA is a significant cause of maternal morbidity and mortality and is now the most common reason for emergent postpartum hysterectomy. Its prevalence has risen tenfold in the United States over the past 50 years, primarily due to the increasing percentage of pregnant patients undergoing primary and repeat cesarean sections. Placenta previa and previous cesarean section are the two most important known risk factors for PA. Accurate prenatal identification of affected pregnancies allows optimal obstetric management. Ultrasonography (US) remains the diagnostic standard, and routine US examination at 18-20 weeks gestation affords an ideal opportunity to screen for the disorder. Placental lacunae and abnormal color Doppler imaging patterns are the most helpful US markers for PA. In recent years, there has been increased interest in magnetic resonance (MR) imaging for the evaluation of PA, since it can provide information on depth of invasion and more clearly depict posterior placentas. The most reliable MR imaging findings are uterine bulging, heterogeneous placenta, and placental bands. Focal interruptions in the hypointense myometrial border may also be helpful. PA is a clinical and diagnostic challenge that is being encountered with increasing frequency. Clinicians should be aware of the clinical issues, risk factors, and imaging findings associated with PA to facilitate optimal case management.

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    • "As in the literature [14], [20], [22], [23], [31]–[34], we found the best PPV (90%) of MRI when dark intraplacental bands were associated with disappearance of the myometrium and uterine bulging. Lim et al. also showed that the volumes of dark intraplacental bands on T2-weighted images were significantly different in the patients with abnormal placentation and without placenta accreta (p = 0.047), and that band volumes were differed significantly between patients with accreta, increta, and percreta (p<0.0005)[12]. "
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    ABSTRACT: 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. 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. 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%. Ultrasound imaging is the mainstay of screening for placenta accreta. MRI appears to be complementary to ultrasonography, especially when there are few ultrasound signs.
    Full-text · Article · Apr 2014 · PLoS ONE
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    • "The incidence of placenta accrete has increased from approximately 0.8/1000 deliveries in the 1980s to 3/1000 deliveries in the past decade [4, 5]. The early diagnosis of placenta previa is usually made by ultrasound [6], although in recent years there has been an interest in the use of MR imaging [6, 7]. Despite the early and accurate prenatal diagnosis, hysterectomy remains the most common surgical procedure in cases of PPH for placenta previa accreta [8]. "
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    ABSTRACT: Placenta percreta is one of the most serious complications of placenta previa and is frequently associated with severe obstetric hemorrhage usually necessitating hysterectomy. We present a case of placenta previa percreta diagnosed by ultrasound and magnetic resonance imaging techniques, in which we accomplished conservative management of postpartum hemorrhage. The management we propose includes the following steps: preventive catheterization of the descending aorta via transhumeral access; Stark cesarean delivery; uterotonics drugs; Affronti endouterine square hemostatic sutures; intrauterine application of Bakri balloon and partial filling with 100 mL of normal saline; B Lynch suture, hysterorrhaphy, and filling a Bakri balloon with up to 500 mL of normal saline; reversible radiological embolization; and/or surgical ligation of the uterine arteries. The bleeding stopped following placement of Affronti sutures combined with external (B-Lynch suture) and internal (Bakri balloon) uterine compression. Our experience indicates that this conservative method can be considered an option in the management of selected cases of pregnancy at high risk for intrapartum hemorrhage.
    Full-text · Article · Jan 2013
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    • "MRI is often recommended when ultrasound findings are inconclusive.29,33–36 MRI findings suggestive of placenta accrete include uterine bulging, heterogeneous signal intensity within the placenta, dark intraplacental bands on T2-weighted images, tenting of the bladder, and direct visualization of placental invasion into pelvic structures.23Figure 5 illustrates ultrasound examination with Doppler study showing a major anterior placenta previa accreta with bladder wall involvement. The MRI scan was also suggestive of deep myometrial invasion by placental tissue, but the bladder mucosa was intact. "
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    ABSTRACT: Placenta accreta is a condition of abnormal placental implantation in which the placental tissue invades beyond the decidua basalis. It may invade into or even through the myometrium and adjacent organs, such as the urinary bladder. The incidence has been rising in recent years. It is one of the important obstetric complications nowadays, leading to significant maternal morbidity and mortality. In the past, this condition was often diagnosed at the time of delivery when massive and unexpected hemorrhage occurred. Hysterectomy, associated with significant physical and psychological consequences, was usually the only management option. As more obstetricians have become aware of this condition, early identification with antenatal imaging diagnostic technology has become possible. Ultrasound scan plays an important role in the antenatal diagnosis. Various sonographic features with different specificity and sensitivity have been described in the literature. In equivocal cases, magnetic resonance imaging may be helpful. With such information, more accurate counseling can be offered to the mothers and their families before delivery. The delivery can also be arranged at a favorable time and in an institution where multidisciplinary support is available. Input from a hematologist, interventional radiologist, intensive care physician, urology surgeon, and/or other specialist are desirable. Apart from hysterectomy, various forms of conservative management can also be considered when the diagnosis is made prior to delivery. Fertility can therefore be preserved. After delivery, with or without hysterectomy performed, psychological support to the mothers and their families is essential.
    Preview · Article · Nov 2012 · International Journal of Women's Health
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