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 sixty 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.