MRI of placenta accreta: diagnostic accuracy and impact of interventional radiology on foetal-maternal delivery outcomes in high-risk women

Current state of interventional procedures to treat pernicious placenta previa accompanied by placenta accreta spectrum: A review

Pernicious placenta previa (PPP) accompanied by placenta accreta spectrum (PAS) is a life-threatening placental implantation that causes a variety of complications, including antepartum hemorrhage, postpartum hemorrhage, hemorrhagic shock, preterm birth, and neonatal asphyxia. Along with continuous improvements in medical technology, interventional procedures have been widely used to prevent intraoperative hemorrhage associated with PPP. The commonly used interventional procedures include abdominal aorta clamping, prophylactic balloon occlusion of the internal or common iliac arteries, and uterine artery embolization. The above-mentioned interventional procedures have their respective advantages and disadvantages. The best procedure for different situations continues to be debated considering the complex pattern of blood supply to the uterus in patients with PPP. The specific choice of interventional procedure depends on the clinical situation of the patient with PPP. For grade III PAS, the need for uterine artery embolization is assessed based on blood loss and preoperative hemostatic effect following abdominal aorta clamping. Repair or hysterectomy may be performed following uterine artery embolization if there is a hybrid operating room for grade III PAS patients with extensive sub-serosal penetration of the uterus and repair difficulty. For grade II PAS (shallow placental implantation), prophylactic balloon occlusion may not be necessary before surgery. Uterine artery embolization can be performed in case of postoperative hemorrhage.

Performance of magnetic resonance imaging to predict maternal outcomes in patients at high risk for placenta accreta spectrum disorder

OBJECTIVE

The purpose of this study is to evaluate the diagnostic performance of MRI parameters to predict adverse maternal peripartum outcomes in pregnant females at high-risk for placenta accreta spectrum (PAS) disorder.

METHODS AND MATERIALS

This retrospective study evaluated 60 pregnant females who underwent MRI for placental assessment. MRI studies were reviewed by a radiologist blinded to all clinical data. MRI parameters were compared with five maternal outcomes: severe bleeding, cesarean hysterectomy, prolonged operation time, need for blood transfusion, and need for intensive care unit (ICU) admission. The MRI findings were associated with pathologic and/or intraoperative findings for PAS.

RESULTS

The study identified 46 cases of PAS disorder and 16 cases of placenta percreta. The agreement between the radiologist impression of PAS disorder and the intraoperative/histological findings was substantial (0.67, p < 0.001), and almost perfect for the presence of placenta percreta (0.87, p < 0.001). The presence of a placental bulge was highly associated with placenta percreta, with sensitivity of 87.5% and specificity of 90.9%. The MRI signs that associated with more maternal outcomes were myometrial thinning, with significant odds ratio for severe blood loss (20.2), hysterectomy (4.0), need for blood transfusion (4.8) and prolonged surgery time (4.9), and uterine bulging, with significant odds ratio for severe blood loss (11.9), hysterectomy (34.0), ICU admission (5.0), and need for blood transfusion (4.8).

CONCLUSION

MRI signs significantly correlated with invasive placenta and were independently associated with adverse maternal outcomes. The presence of a placental bulge was highly accurate in predicting placenta percreta.

ADVANCES IN KNOWLEDGE

First study to evaluate the strength of the association between individual MRI signs and five adverse maternal outcomes. Conclusions support published MRI signs associated with placental invasion, especially regarding the value placental bulging in predicting placenta percreta.

Ultrasonographic Prediction of Placental Invasion in Placenta Previa by Placenta Accreta Index

This study aimed to investigate the diagnostic accuracy of the placenta accreta index (PAI) for predicting placenta accreta spectrum (PAS) in women with placenta previa. We analyzed 33 pregnancies with placenta previa at Keio University Hospital. The PAI was assessed in the early third trimester, and PAS was diagnosed histologically or clinically defined as retained placenta after manual removal attempts. The PAI and incidence of PAS were analyzed. Ten women (30%) were diagnosed with PAS and had higher volumes of perioperative bleeding (p = 0.016), higher rate of requiring uterine artery embolization (p = 0.005), and peripartum hysterectomy (p = 0.0002) than women without PAS. A PAI > 2 was the most useful cut-off point for predicting PAS and was more sensitive than prediction values using traditional evaluation (history of cesarean section and placental location). Post-hoc analysis revealed a higher rate of previous history of cesarean delivery (30% vs. 4.4%, p = 0.038), severe placental lacunae (≥grade2) (70% vs. 8.7%, p = 0.0003), thin myometrial thickness (90% vs. 22%, p = 0.0003), anterior placenta (100% vs. 30%, p = 0.0002), and presence of bridging vessels (30% vs. 0%, p = 0.0059) in PAS women. PAI could help predict the outcomes of women with placenta previa with and without a history of cesarean delivery to reduce PAS-induced perinatal complications.

Quality of surgical management of placenta accreta spectrum in a tertiary center in Sri Lanka: baseline study for quality improvement project: problems and solutions

Introduction

Placenta accreta spectrum (PAS) is associated with a multitude of maternal and fetal complications. Events related to its management have resulted in significant psychological morbidity, with lifelong consequences which warrant continuous support to cope with their lives. The objective of the study is to highlight the importance of multidisciplinary holistic care and explore room for improvement in the provision of care for women with PAS.

Methods

Our study was conducted on deliveries complicated with PAS from January 2019 to June 2021. 27 women were diagnosed with PAS during this period and received treatment. Impact of life event scale- revised (IES-R) and short form health survey-36(SF-36) questionnaires were administered to assess the impact of PAS on their lives. In depth interviews were conducted with the women. A multidisciplinary team meeting was later conducted to formulate a comprehensive care plan for women with PAS.

Results

The response rate was 96.2%. Mean age of the sample is 34.1 years (SD 4.3). Interval to current pregnancy varies from 0.6 years to 10 years with mean of 4.6 years. Mean gestational age of diagnosis of PAS was 25.4(SD 6.7) weeks. The care bundle provided for women with PAS was evaluated in all cases.

Surgery was conducted electively in 82% of patients. Blood transfusions were noted in 85%. Mean pre-operative stay was 9.5 days (SD 8.3) and mean post-operative stay was 8.8 days (SD 8). Total hospital stay ranged from 6 to 48 days (mean 19.5 days, SD 11.4).

IES-R scores were significant in 4/26 patients. There was no correlation with the interval from the surgery with any of the subscales or with the total scores. The lapsed time after the surgery had a significant correlation with physical functioning and pain domains of the SF-36 questionnaire.

Description of the experience, loss of femininity with loss of the uterus, concerns and fears about the future and measures to improve the quality of care were the themes identified and described.

A multidisciplinary team meeting, consisting of consultant obstetricians performing surgery for PAS, anesthetists, hematologist, transfusion medicine specialist, urologist, physiotherapist, nutritionist and nursing officers from ICU and wards, was held and their contributions helped to map out a definitive care plan.

Conclusions

PAS is associated with long term physical and psychological morbidity. Continuous support through quarterly clinic visits and telephone conversations may alleviate the psychological trauma. However, some physical disabilities may be lifelong and life changing. Importance of reducing primary caesarean section and promoting trial of labour after caesarean delivery should be promoted among patients and caregivers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04840-7.

Diagnosis of placenta accreta spectrum in high-risk women using ultrasonography or magnetic resonance imaging: systematic review and meta-analysis

OBJECTIVES

To perform a systematic review and meta-analysis of the diagnostic test accuracy of ultrasound and magnetic resonance imaging (MRI) and compare the performance of the two modalities in the diagnosis of placenta accreta spectrum (PAS).

METHODS

This was a systematic review conducted following the Cochrane Diagnostic Test Accuracy Reviews guideline. A literature search was performed in five databases: PubMed, EMBASE, PMC, The Cochrane Library and BVS-Bireme between 27 July and 4 August 2020. The search was updated on 18 August 2021. We included observational studies evaluating diagnostic accuracy in women with risk factors for PAS who had undergone both ultrasound and MRI examinations, published in English between 2011 and 2021. Quality Assessment of Diagnostic Accuracy Studies-2 was used to evaluate the quality of the studies. Forest plots for sensitivity and specificity with 95% CIs and receiver-operating-characteristics curves for ultrasound and MRI were constructed.

RESULTS

The literature search identified 266 studies. After reviewing the titles and abstracts of the articles, 51 were selected for full-text review and 17 studies including 1301 women with MRI and ultrasound data available were selected for the meta-analysis. The study population included 457 cases with PAS diagnosed using the gold standard method (intraoperative or histopathological analysis). The overall quality of the evaluated studies was considered satisfactory according to QUADAS-2. The meta-analysis revealed a sensitivity of 0.833 (95% CI, 0.776-0.878) and specificity of 0.834 (95% CI, 0.746-0.897) for ultrasound. For MRI, sensitivity was 0.838 (95% CI, 0.786-0.879) and specificity was 0.831 (95% CI, 0.770-0.878). There was no statistically significant difference between the two modalities. The Cochran's Q values indicated a high level of heterogeneity of sensitivity and specificity of ultrasound and MRI across studies.

CONCLUSIONS

Ultrasound and MRI have similar accuracy in the diagnosis of PAS. These results suggest that, in a setting with a high prevalence of risk factors, the choice of imaging modality for initial screening for PAS should depend on the availability of equipment and the examiner's expertise. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Placenta Accreta Spectrum

Placenta accreta spectrum (PAS) refers to the range of pathologic adherence of the placenta to the uterine myometrium, including the placenta accreta, increta, and percreta. The incidence of PAS is rising primarily because of an increase in related risk factors, such as the rate of cesarean deliveries and pregnancies resulting from assisted reproductive technology. The maternal risks associated with PAS are significant, including hemorrhage, hysterectomy, and death. Fetal and neonatal risks are primarily the result of premature delivery. Antenatal diagnosis via ultrasonography and magnetic resonance imaging remains imperfect. Management of PAS varies, however, and there is a clear improvement in maternal outcomes with an antenatal diagnosis compared with unexpected diagnosis at the time of delivery. Studies that evaluate the balance between maternal and fetal/neonatal risks of expectant management versus preterm delivery have found that planned delivery between 34 and 35 weeks' gestation optimizes outcomes. Multidisciplinary PAS care teams have become the norm and recommended approach to management, given the complexity of caring for this obstetrical condition. Although significant advances have been made over the years, large knowledge gaps remain in understanding the pathophysiology, diagnosis, and clinical management.