Ultrasound Imaging of Placenta Accreta With MR Correlation

Placental volume as a novel sign for identifying placenta accreta spectrum in pregnancies with complete placenta previa

BACKGROUND

Placenta accreta spectrum (PAS) carries an increased risk of maternal-fetal mortality and morbidity, and magnetic resonance imaging (MRI) features for PAS have been used for preoperative identification. This study aims to investigate the role of placental volume evaluated by MRI in identifying PAS in pregnant women with complete placenta previa.

METHODS

Totally 163 cases of complete placenta previa pregnant women with a history of cesarean section underwent MRI for suspected PAS were included. We categorized the patients into two groups according to the presence or absence of PAS, and the maternal-fetal perinatal outcomes and placental volume analyzed by 3D Slice software were compared.

RESULTS

There were significantly more gravidity, parity, and number of previous cesarean delivery in the PAS group (P < 0.05). Significant differences were also found between the two groups with respect to the following baseline characteristics: gestational age at delivery, intraoperative blood loss, blood transfusion, and neonatal birth weight (P < 0.05). Of 163 women in the study, 7 (4.294%) required cesarean hysterectomy for high-grade PAS or pernicious bleeding during cesarean section, and PAS was confirmed with histologic confirmation in 6 (85.714%) cases. The placental volume in PAS group was greater than that in the non-PAS group (P < 0.05). With a threshold of more than 887 cm3, the sensitivity and specificity in identifying PAS were 85.531% and 83.907% respectively, with AUC 0.908 (95% CI: 0.853-0.948).

CONCLUSIONS

Placental volume may be a promising indicator of PAS in complete placenta previa patients with a history of cesarean section.

Enhancing postpartum hemorrhage prediction in pernicious placenta previa: a comparative study of magnetic resonance imaging and ultrasound nomogram

Objective: To explore the risk factors of postpartum hemorrhage (PPH) in patients with pernicious placenta previa (PPP) and to develop and validate a clinical and imaging-based predictive model. Methods: A retrospective analysis was conducted on patients diagnosed surgically and pathologically with PPP between January 2018 and June 2022. All patients underwent PPP magnetic resonance imaging (MRI) and ultrasound scoring in the second trimester and before delivery, and were categorized into two groups according to PPH occurrence. The total imaging score and sub-item prediction models of the MRI risk score/ultrasound score were used to construct Models A and B/Models C and D. Models E and F were the total scores of the MRI combined with the ultrasound risk and sub-item prediction model scores. Model G was based on the subscores of MRI and ultrasound with the introduction of clinical data. Univariate logistic regression analysis and the logical least absolute shrinkage and selection operator (LASSO) model were used to construct models. The receiver operating characteristic curve andision curve analysis (DCA) were drawn, and the model with the strongest predictive ability and the best clinical effect was selected to construct a nomogram. Internal sampling was used to verify the prediction model's consistency. Results: 158 patients were included and the predictive power and clinical benefit of Models B and D were better than those of Models A and C. The results of the area under the curve of Models B, D, E, F, and G showed that Model G was the best, which could reach 0.93. Compared with Model F, age, vaginal hemorrhage during pregnancy, and amniotic fluid volume were independent risk factors for PPH in patients with PPP (p < 0.05). We plotted the DCA of Models B, D, E, F, and G, which showed that Model G had better clinical benefits and that the slope of the calibration curve of Model G was approximately 45°. Conclusion: LASSO regression nomogram based on clinical risk factors and multiple conventional ultrasound plus MRI signs has a certain guiding significance for the personalized prediction of PPH in patients with PPP before delivery.

Placenta accreta spectrum: the pattern and character of intraplacental blood flow by color and spectral Doppler

PURPOSE

To characterize intraplacental blood flow patterns in placenta accreta spectrum (PAS) with color and spectral Doppler imaging.

METHODS

Thirty-two patients at risk for PAS underwent ultrasound imaging with both color and spectral Doppler. The placenta was inspected for areas of vascularity by color Doppler, particularly within the lower uterine segment. Spectral Doppler waveforms were obtained from these vessels and categorized as either intraplacental or subplacental (myometrial), venous or arterial, fetal or maternal (based on heart rate). Arterial waveforms were measured for heart rate, peak systolic velocity, end diastolic velocity, and resistive index. Statistical comparisons were made between cases with and without PAS using Fisher exact tests (categorical variables) and Mann-Whitney U tests (numerical indices). Interobserver agreement was characterized with kappa coefficients.

RESULTS

At delivery, there were 19 cases with PAS and 13 without PAS. On ultrasound studies, clustered intraplacental vascularity was found in the lower uterine segment in 66% of cases (95% of PAS cases and 23% cases without PAS; p < 0.0001). Maternal arterial waveforms were found within the vascular cluster in 84% of PAS cases and 15% of cases without PAS (p < 0.0001). A traversing fetal artery was found within the vascular cluster in 56% of cases (84% PAS cases and 15% cases without PAS; p = 0.001). Venous waveforms were found in 84% of PAS cases and 15% of cases without PAS. Interobserver agreement was good to excellent.

CONCLUSION

Intraplacental blood flow pattern in PAS is characterized by an intraplacental vascular cluster containing low-resistance maternal arterial flow and transplacental fetal arteries.

Retained Morbidly Adherent Placenta Presenting as a Myometrial Mass in Patients With Vaginal Bleeding: A Case Series and Review of Current Literature

ABSTRACT

The differential diagnosis for a uterine mass and vaginal bleeding after abortion or delivery is broad and includes both benign and malignant causes. A rare etiology for this condition is retained morbidly adherent placenta. Few cases of retained morbidly adherent placenta presenting as a myometrial mass in the setting of vaginal bleeding have been described in the medical literature. In this case series and review of the current literature, we describe the ultrasound features of 3 retained morbidly adherent placentae, along with correlative magnetic resonance imaging findings.

MRI-radiomics-clinical-based nomogram for prenatal prediction of the placenta accreta spectrum disorders

OBJECTIVES

To investigate whether an MRI-radiomics-clinical-based nomogram can be used to prenatal predict the placenta accreta spectrum (PAS) disorders.

METHODS

The pelvic MR images and clinical data of 156 pregnant women with pathologic-proved PAS (PAS group) and 115 pregnant women with no PAS (non-PAS group) identified by clinical and prenatal ultrasonic examination were retrospectively collected from two centers. These pregnancies were divided into a training (n = 133), an independent validation (n = 57), and an external validation (n = 81) cohort. Radiomic features were extracted from images of transverse oblique T2-weighted imaging. A radiomics signature was constructed. A nomogram, composed of MRI morphological findings, radiomic features, and prenatal clinical characteristics, was developed. The discrimination and calibration of the nomogram were conducted to assess its performance.

RESULTS

A radiomics signature, including three PAS-related features, was associated with the presence of PAS in the three cohorts (p < 0.001 to p = 0.001). An MRI-radiomics-clinical nomogram incorporating radiomics signature, two prenatal clinical features, and two MRI morphological findings was developed, yielding a higher area under the curve (AUC) than that of the MRI morphological-determined PAS in the training cohort (0.89 vs. 0.78; p < 0.001) and external validation cohort (0.87 vs. 0.75; p = 0.003), while a comparable AUC value in the validation cohort (0.91 vs. 0.81; p = 0.09). The calibration was good.

CONCLUSIONS

An MRI-radiomics-clinical nomogram had a robust performance in antenatal predicting the PAS in pregnancies.

KEY POINTS

• An MRI-radiomics-clinical-based nomogram might serve as an adjunctive approach for the treatment decision-making in pregnancies suspicious of PAS. • The radiomic score provides a mathematical formula that predicts the possibility of PAS by using the MRI data, and pregnant women with PAS had higher radiomic scores than those without PAS.

Assessment of postpartum haemorrhage for placenta accreta: Is measurement of myometrium thickness and dark intraplacental bands using MRI helpful?

Background

This study aimed to investigate the predictive values of magnetic resonance imaging (MRI) myometrial thickness grading and dark intraplacental band (DIB) volumetry for blood loss in patients with placenta accreta spectrum (PAS).

Methods

Images and clinical data were acquired from patients who underwent placenta MRI examinations and were diagnosed with PAS from March 2015 to January 2021. Two radiologists jointly diagnosed, processed, and analysed the MR images of each patient. The analysis included MRI-based determination of placental attachment, as well as myometrial thickness grading and DIB volumetry. The patients included in the study were divided into three groups according to the estimated blood loss volume: in the general blood loss (GBL) group, the estimated blood loss volume was < 1000 ml; in the massive blood loss (MBL) group, the estimated blood loss volume was ≥ 1000 ml and < 2000 ml; and in the extremely massive blood loss (ex-MBL) group, the estimated blood loss volume was ≥ 2000 ml. The categorical, normally distributed, and non-normally distributed data were respectively analysed by the Chi-square, single-factor analysis of variance, and Kruskal–Wallis tests, respectively. The verification of correlation was completed by Spearman correlation analysis. The evaluation capabilities of indicators were assessed using receiver operating characteristic curves.

Results

Among 75 patients, 25 were included in the GBL group, 26 in the MBL group, and 24 in the ex-MBL group. A significant negative correlation was observed between the grade of myometrial thickness and the estimated blood loss (P < 0.001, ρ = − 0.604). There was a significant positive correlation between the volume of the DIB and the estimated blood loss (P < 0.001, ρ = 0.653). The areas under the receiver operating characteristic curve of the two MRI features for predicting blood loss ≥ 2000 ml were 0.776 and 0.897, respectively.

Conclusions

The grading and volumetric MRI features, myometrial thickness, and volume of DIB, can be used as good prediction indicators of the risk of postpartum haemorrhage in patients with PAS.

Intelligent Recognition Algorithm-Based Color Doppler Ultrasound in the Treatment of Dangerous Placenta Previa

The study focused on the clinical diagnostic value of color Doppler ultrasound of dangerous placenta previa patients under the guidance of intelligent recognition algorithms. 58 patients with placenta previa and placenta accreta admitted to the hospital for treatment were selected as research subjects. The color Doppler ultrasound under the guidance of intelligent recognition algorithm was compared with the two-dimensional ultrasound for specificity, sensitivity, and accuracy. The color Doppler ultrasound results showed that, of the 58 patients, there were 32 cases of complete placenta previa and 26 cases of incomplete placenta previa, which were consistent with the surgical pathology results. It was found that patients with malignant placenta previa and placenta accreta had thickened placenta, disappeared posterior placental space, myometrium <2 mm, and increased incidence of cervical enlargement (P < 0.05). In conclusion, the recognition accuracy of color Doppler ultrasound under the guidance of the intelligent recognition algorithm is more than 90%, and it can effectively identify dangerous placenta previa, assisting doctors in diagnosis and treatment of dangerous placenta previa.

Magnetic Resonance Imaging of Placenta Accreta Spectrum: A Step-by-Step Approach

Placenta accreta spectrum (PAS) is an abnormal placental adherence or invasion of the myometrium or extrauterine structures. As PAS is primarily staged and managed surgically, imaging can only guide and facilitate diagnosis. But, imaging can aid in preparations for surgical complexity in some cases of PAS. Ultrasound remains the imaging modality of choice; however, magnetic resonance imaging (MRI) is required for evaluation of areas difficult to visualize on ultrasound, and the assessment of the extent of placenta accreta. Numerous MRI features of PAS have been described, including dark intraplacental bands, placental bulge, and placental heterogeneity. Failure to diagnose PAS carries a risk of massive hemorrhage and surgical complications. This article describes a comprehensive, step-by-step approach to diagnostic imaging and its potential pitfalls.

Prenatal Diagnosis of Placental Invasion: A Systematic Review and Meta-analysis on Accuracy of Ultrasonography and MRI in Diagnosis of Placental Invasion

Objective:

The aim of this systematic review and meta-analysis was to evaluate and compare the diagnostic accuracy of ultrasonography (US) and magnetic resonance imaging (MRI) in the diagnosis of placental invasion.

Method:

Two independent scientists carried out a series of searches to obtain relevant research, released from January 1, 2009, to December 31, 2018. National databases (Magiran and SID), KoreaMed, and LILACS were reviewed for literature, released in other languages. A series of MeSH keywords was employed as part of the searching strategy (e.g., pregnancy, pregnant, placental invasion, accreta). A forest plot was built with Meta-DiSc, version 1.4.

Results:

For placental invasion, the sensitivity and specificity of MRI were 89% (95% confidence interval [CI], 83%–93% with a 95% confidence interval) and 97% (95% CI, 93%–99%), respectively. The sensitivity and specificity of US were 73% (95% CI, 66%–79%) and 89% (95% CI, 84%–93%), respectively. In the detection of placenta accreta solely (as the first grade of placental invasion), the sensitivity and specificity of MRI were 89.3% (95% CI, 86%–92%) and 84% (95% CI, 77%–89.6%). The sensitivity and specificity of US detection were 95.4% (95% CI, 93.8%–96.6%) and 87.3% (95% CI, 81.4%–91.9%), respectively.

Conclusion:

Due to the increased cesarean sections, placental invasion may be increasing. The diagnosis of prenatal placental invasion is important to reduce maternal morbidity and mortality. Recent trends indicate an increased use of MRI to evaluate placental invasion as a complement to US. The most accurate imaging findings are using US for placental lacunae and MRI to detect the dark intraplacental band.

Ultrasound accuracy in prenatal diagnosis of abnormal placentation of posterior placenta previa

OBJECTIVES

To evaluate the accuracy of ultrasound in prenatal diagnosis of Placenta accrete spectrum disorders in patients with posterior placenta previa, and to assess the impact of prenatal diagnosis in our population.

STUDY DESIGN

We prospectively enrolled 198 women with posterior placenta previa from 2011 to 2017. We performed transabdominal and transvaginal ultrasound examinations (Grey-scale and colour/power Doppler). The diagnosis of placenta accreta spectrum disorders was based on detection of at least two of the following criteria: loss of retroplacental clear zone, interruption of uterine serosa-bladder wall interface, turbulent placental lacunae with high velocity flow, myometrial thickness <1 mm, increased vascularity of uterine serosa-bladder wall interface, loss of vascular arch parallel to basal plate and/or irregular intraplacental vascularization. Definitive diagnosis was made at delivery with Caesarean section. Furthermore, we compared maternal outcomes in cases diagnosed antenatal versus that one's diagnosed at delivery.

RESULTS

There were 20/198 cases of placenta accreta spectrum disorders. The two-criteria system identified 12 cases of placenta accreta, providing a 60.0% of sensitivity, 98.8% of specificity, 85.7% of positive and 95.7% of negative predictive value. Maternal outcomes were better in women with prenatal diagnosis of placenta accreta spectrum disorders, although not statistical significant.

CONCLUSIONS

Our data showed that grey-scale and Color-Doppler ultrasound evaluation for detecting placenta accreta spectrum disorders on posterior placenta previa have high specificity, positive and negative predictive value, but a low sensitivity. Nevertheless, an antenatal diagnosis of placenta accreta spectrum disorders for posterior placenta previa should be encouraged.

Texture analysis of placental MRI: can it aid in the prenatal diagnosis of placenta accreta spectrum?

PURPOSE

To determine if texture analysis can differentiate placenta accreta spectrum (PAS) from normal placenta on MRI.

METHODS

We performed retrospective image analysis of 80 patients, comprised of 46 patients with PAS and 34 patients without PAS. Histopathology was used as the reference standard. Sagittal single shot fast spin echo T2-weighted MRI sequences acquired from a single institution were analyzed. Placental heterogeneity was quantified using in-house software on a Matlab platform, including the standard deviation of pixel intensity, coefficient of variation, gray-level co-occurrence matrices (GLCM), histogram-oriented gradients (HOG), and fractal analysis with box sizes from 2 to 512. Two-tailed unpaired Student's t test was used with statistical significance of p < 0.05.

RESULTS

PAS was associated with higher values for standard deviation of pixel intensity and fractal analysis at every box size. Fractal analysis at box sizes 256 (p = 0.011) and 32 (p = 0.021), and standard deviation of pixel intensity (p = 0.023) were the most statistically significant. Fractal values at box size 256 for PAS was 0.13 versus 0.090 for patients without PAS, while standard deviation of pixel intensity was 3.7 for PAS versus 2.5 for patients without PAS. No statistically significant association between PAS and GLCM, coefficient of variation, and HOG was found.

CONCLUSION

Statistically significant differences were found between normal and abnormal groups using standard deviation of pixel intensity and fractal analysis.

Scoring system for the prediction of the severity of placenta accrete spectrum in women with placenta previa: a prospective observational study

PURPOSE

The clinical outcomes are significantly different in accreta, increta, and percreta. There is currently no scoring system that can preoperatively distinguish its severity in an at-risk population. The aim of this study is to establish a scoring system for the prediction of the severity of placenta accrete spectrum (PAS) in women with placenta previa.

METHODS

A prospective observational study was conducted in patients with placenta previa who delivered at a Chinese tertiary care center between June 12, 2016 and June 30, 2018. Optimal scaling regression was performed to determine the parameters which really contribute to the prediction of PAS, and calculate percentage of contribution.

RESULTS

Among 392 cases with placenta previa, 79, 53, and 28 had been surgically and/or histologically confirmed as accreta, increta, or percreta, respectively. Seven parameters were scheduled for the estimated scores for PAS, and five of them were finally entered into the predictive model. Their percentage of contribution was as follows: placental lacunas (19%), vascularity at the uterus-bladder interface (17.5%), myometrial thickness and hypoechoic retroplacental zone (25.6%), bladder line (22.6%), and previous caesarean sections (15.3%). The thresholds of scores for the prediction of accreta, increta, and percreta yielded 2.25-6.2, 6.2-8.95, and ≧ 8.95, respectively, with the positive and negative predictive value, and false positive rates of the scoring system were 96.68%, 95.44%, and 3.32%, respectively.

CONCLUSIONS

The scoring system can predict the severity of PAS in women with placenta previa. This will help identify the actual high-risk patients and improve their treatment.

MRI prognosticators for adverse maternal and neonatal clinical outcome in patients at high risk for placenta accreta spectrum (PAS) disorders

BACKGROUND

Placenta accreta spectrum (PAS) disorders may be associated with significant mortality and morbidity for both mother and fetus.

PURPOSE/HYPOTHESIS

To identify MRI risk factors for poor peripartum outcome in gravid patients at risk for PAS.

STUDY TYPE

Prospective.

POPULATION

One hundred gravid women (mean age: 34.9 years) at third trimester, with placenta previa.

FIELD STRENGTH/SEQUENCE

T₂ -SSTSE (single-shot turbo spin echo), T₂ -TSE, T₁ -TSEFS (TSE images with fat-suppression) at 1.5T.

ASSESSMENT

Fifteen MRI features considered indicative of PAS were recorded by three radiologists and were tested for any association with the following adverse peripartum maternal and neonatal events: increased operation time, profound blood loss, hysterectomy, bladder repair, ICU admission, prematurity, low birthweight, and 5-minute APGAR score <7.

STATISTICAL TESTS

Kappa (K) coefficients were computed as a measure of agreement between intraoperative information/histology and MRI results as well as for interobserver agreement; chi-square and Fisher's exact tests were used to explore the association of the MRI signs with clinical complications. A score was calculated by adding all recorded MRI signs and its predictive ability was tested using receiver operating characteristic (ROC) analysis, against all complications, separately; odds ratios (ORs) for optimal cutoffs were determined with logistic regression analysis.

RESULTS

There was excellent agreement (K >0.75, P < 0.001) between MRI and intraoperative findings for invasive placenta, bladder and parametrial involvement. Intraplacental T₂ dark bands, myometrial disruption, uterine bulge, and hypervascularity at the utero-placental interface or parametrium, showed significant association (P < 0.005) with poor clinical outcome for both mother and fetus. The MRI score showed significant predictive ability for each adverse maternal event (area under the curve [AUC]: 0.85-0.97, P < 0.001). The presence of ≥3 MRI signs was the cutoff point for a complicated delivery (OR: 19.08, 95% confidence interval [CI]: 6.05-60.13) and ≥6 MRI signs was the cutoff point for massive bleeding (OR: 90.93, 95% CI: 11.3-729.23), hysterectomy (OR: 72.5, 95% CI: 17.9-293.7), or extensive bladder repair (OR: 58.74, 95% CI: 7.35-469.32). The MRI score was not significant for predicting adverse neonatal events including preterm delivery (P = 0.558), low birthweight (P = 0.097), and 5-minute Apgar score (P = 0.078).

DATA CONCLUSION

Preoperative identification of specific MRI features may predict peripartum course in high-risk patients for PAS.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:602-618.

Morphological evaluation of cervix using MRI at 32 to 36 weeks of gestation: Findings for predicting invasive placenta previa

This study is to investigate the role of cervical morphology evaluated by magnetic resonance imaging (MRI) in predicting invasive placenta previa (IPP).Totally 105 cases of pregnant women underwent prenatal placental MRI at 32 to 36 weeks of gestation for suspected IPP were included in this study. Cervical morphology (cervical length and placental protrusion) was evaluated independently by 2 radiologists. The association between the cervical morphology and surgery findings was analyzed.Totally, 57 pregnant women were confirmed as IPP. For invasion degree, there were 17 cases with placenta percreta and 40 with accreta. For invasion topography, there were 27 cases with S1 invasion and 30 with S2 invasion. The sensitivity and specificity for the MRI sign of placental protrusion in evaluating cervical invasion of IPP were 100% and 100%, respectively. All the 7 IPP patents with cervical invasion received total hysterectomy and had severe blood loss (3500-6000 mL). The IPP patients with S2 invasion had shorter cervical length than those with S1 invasion (2.66 ± 0.66 cm vs 3.24 ± 0.64 cm, P <.001). However, cervical lengths did not correlate with the degree of invasion (placenta percreta vs placenta accreta: 2.82 ± 0.86 vs 2.99 ± 0.60, P = .21).Placental protrusion is a reliable MRI sign for cervical invasion of IPP, and cervical lengths correlate with the invasion topography.

Use of Postpartum Magnetic Resonance Imaging for Diagnosis and Classification of Retained Placenta Tissue

OBJECTIVE

To study the potential application of magnetic resonance imaging (MRI) for classification of retained placental tissue (RPT) in the uterus postnatally.

METHODS

Twenty-two patients with clinically or pathologically proven RPT were studied.

RESULTS

The thickness ratio (D1/D2) of invaded (D1) to normal (D2) myometrium could be categorized into 3 groups (>0.6, 0.1-0.6, and <0.1) correlating with the 3 types of RPT: accreta vera (RPA), increta (RPI), and percreta (RPP) (r = -0.861, P < 0.01). After uterine arterial embolization, the RPT showed lower signal intensity than the myometrium without flow voids on T2-weighted images. Two cases of RPP showed gradual enhancement, except 1 case of infection and 2 cases that did not involve enhancement examinations, whereas 17 cases of RPA and RPI showed early enhancement.

CONCLUSIONS

Magnetic resonance imaging can facilitate diagnosis of RPT severity. Dynamic contrast enhancement can indicate RPT activity and blood supply, thereby ensuring appropriate clinical decision making.

Placenta Percreta and Uterine Rupture in the First Trimester of Pregnancy

Spontaneous uterine rupture in the first trimester of pregnancy is uncommon and difficult to diagnose. Although extremely rare, it is important to consider the occurrence of placenta percreta as differential diagnosis of acute hemorrhagic abdomen at the beginning of pregnancy. We describe below a case of uterine rupture in the first trimester of pregnancy related to placenta percreta.

Anesthetic management of cesarean section in cases of placenta accreta, with versus without abdominal aortic balloon occlusion: study protocol for a randomized controlled trial

BACKGROUND

Placenta accreta (PA), a severe complication during delivery, is closely linked with massive hemorrhage which could endanger the lives of both mother and baby. Moreover, the incidence of PA has increased dramatically with the increasing rate of cesarean deliveries in the past few decades. Therefore, studies evaluating the effects of different perioperative managements based on different modalities in the treatment of PA are necessary. Among the numerous treatment measures, prophylactic abdominal aortic balloon occlusion (AABO) in combination with cesarean section for PA seems to be more advantageous than others. However, up to now, all studies on AABO were almost retrospective. Current evidence is insufficient to recommend for or against routinely using the AABO technology for control intraoperative hemorrhage in patients with PA. Thus, we hope to carry out a prospective, randomized controlled trial (RCT) study to confirm the effectiveness of the AABO technology in patients with PA.

METHODS/DESIGN

This trial is an investigator-initiated, prospective RCT that will test the superiority of AABO in combination with cesarean section compared to the traditional hysterectomy following cesarean section for parturients with PA. A total of 170 parturients with PA undergoing cesarean section will be randomized to receive either AABO in combination with cesarean section or the traditional hysterectomy following cesarean section. The primary outcome is estimated blood loss. The most important secondary outcome is the occurrence of cesarean hysterectomy during delivery; others include blood transfusion volume, operating time, neonate's Apgar scores (collected at 1, 5 and 10 min), length of stay in intensive care unit, total hospital stay, and balloon occlusion-relative data.

DISCUSSION

This prospective trial will test the superiority of AABO in combination with cesarean section compared to the traditional hysterectomy following cesarean section for parturients with PA. It may provide strong evidence about the benefits and risks of AABO in combination with cesarean section for parturients with PA.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-INR-16008842 . Registered on 14 July 2016.

Abnormal placentation: the role of MRI in diagnosis and therapeutic planning

AIM

To evaluate the role of magnetic resonance imaging (MRI) for diagnosis and therapeutic planning in patients with abnormal placentation (AP).

MATERIALS AND METHODS

Overall, 168 consecutive patients with suspected placenta previa and AP were referred for MRI before caesarean section (CS). The ability of MRI to properly detect and assess abnormal placentation was correlated with findings at CS, which were considered the reference standard diagnostic tool. For each patient, MRI was used to determine whether the AP was suitable for complete/incomplete delivery, hysterectomy, or conservative treatment. Treatment planning with MRI was prospectively compared with the actual treatment that had been carried out in each patient decided at CS.

RESULTS

Placenta previa was detected at MRI in 63 patients and AP in 105 patients; 16 patients had false-positive MRI findings, and three had false-negative findings. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI compared to findings at CS were 88.9% (149 of 168), 96.7% (89 of 92), 78.9% (60 of 76), 84.8% (89 of 105), and 95.2% (60 of 63), respectively. Treatment planning could be correctly made on the basis of MRI with accuracy, sensitivity, specificity, PPV, and NPV of 97%, 100%, 92.6%, 95.2%, and 100%, respectively.

CONCLUSIONS

MRI offers high diagnostic accuracy in the detection of AP, and it may be helpful in the detailed planning of treatment.