Background: Intra-operative bleeding during CS due to placenta accreta spectrum (PAS) disorders is a major cause of maternal mortality and morbidity. Moreover, a well-planned cesarean section (CS), presence of expert team and preoperative preparation of blood and blood elements decreases blood loss and, consequently, maternal morbidity and mortality. So, we found it important to predict blood loss during CS for PAS using ultrasound that has high accuracy in visualization of placental and subplacental vascularity. So we aimed to evaluate the benefit of ultrasound in predicting intraoperative blood loss during planned cesarian sections in cases of PAS. Methods: This prospective observational study was carried out on 98 pregnant women with placenta previa who had a history of one or repeated CSs and were suspected of having an abnormally invasive placenta in the Obstetrics and Gynecology Department at the Emergency Unit in Zagazig University Hospital. A sonogram was performed, and the amount of blood loss was calculated. Results: Regarding prediction of major hemorrhage, sub-placental hypervascularity and intra-placental hypervascularity showed the highest sensitivity (91.7%) and negative predictive value (93.8% and 90.9%, respectively). Lacunae at the placental-serosal interface showed the highest specificity (91.9%), positive predictive value (40%), and accuracy (73.5%). On multivariate regression analysis, the presence of more than 4 placental lacunae independently increased the risk of major hemorrhage by 3.7 times, while sub-placental hypervascularity independently increased the risk by 5.3 times. Conclusions: Color Doppler ultrasound study of placental and sub-placental vascularity can predict major intraoperative hemorrhage in cases of placenta accreta spectrum