Development and validation of nomograms for predicting blood loss in placenta previa with placenta increta or percreta

BACKGROUND: To develop the risk prediction model of intraoperative massive blood loss in placenta previa with placenta increta or percreta. METHODS: This study included 260 patients, of whom 179 were allocated to the development group and 81 to the validation group. Univariate and multivariate logistic regression analyses were used to identify characteristics that were associated with massive blood loss (≥2,500 mL) during cesarean section. A nomogram was constructed based on regression coefficients. Receiver-operating characteristic curve, calibration curve, and decision curve analyses were applied to assess the discrimination, calibration, and performance of the model. RESULTS: Two models were constructed. The preoperative feature model (model A) consisted of vascular lacunae within the placenta and hypervascularity of the uterine-placental margin, uterine serosa-bladder wall interface, and cervix. The preoperative and surgical feature model (model B) consisted of an emergency cesarean section, no preoperative balloon placement of the abdominal aorta, and the previously mentioned four ultrasound signs. Model B had better discrimination than model A (area under the curve: development group: 0.839 vs. 0.732; validation group: 0.829 vs. 0.736). Model B showed a higher area under the decision curve than model A in both the training and validation groups. CONCLUSIONS: The preoperative and surgical feature model for placenta previa with placenta increta or percreta can improve the early identification and management of patients who are at high risk of intraoperative massive blood loss.