The role of MRI in "estimating" intraoperative bleeding during cesarean section for placenta accreta: A prospective cohort study

The prenatal detection of placenta accreta spectrum (PAS) disorder is crucial for treatment strategy formulation. MRI descriptors may offer a more objective method for predicting PAS and clinical outcomes. The aim of this study is to investigate the predictive value of MRI examination for intraoperative blood loss in PAS cesarean section and elucidating the MRI descriptors that are more valuable for predicting intraoperative blood loss. A prospective study was carried out on 164 pregnant women diagnosed with PAS. Maternal and neonatal perioperative characteristics were systematically collected. To evaluate the relationship between maternal and perioperative characteristics and intraoperative blood loss, as well as the predictive value of MRI descriptors on intraoperative blood loss, a multivariable linear regression analysis was performed. Patients were pre-grouped based on a combined ultrasound-MRI evaluation, with 108 cases (65.9 %) classified as placenta accreta, 47 cases (28.7 %) as placenta increta, and 9 cases (5.4 %) as placenta percreta. The results demonstrated that intraoperative blood loss was positively associated with partial MRI descriptors (F = 9.751, df = 15), such as placenta accreta (OR: 243.33, p = 0.006), cross-border blood vessels that pass through the uterine muscle layer (OR: 297.76, p = 0.012), interruption of hyperechoic uterus-bladder interface (bladder line) (OR: 342.59, p = 0.011), and subplacental hypervascularity (OR: 365.96, p = 0.027). Preoperative MRI demonstrates promising predictive capabilities in estimating intraoperative blood loss for PAS patients. Pregnant women identified as having a high risk of intraoperative bleeding based on MRI findings should undergo closer antenatal monitoring in late pregnancy, along with more comprehensive preoperative blood preparation, to better ensure maternal and fetal safety.