Background: The worldwide incidence of placenta accreta spectrum (PAS) is rapidly increasing, following the trend of rising cesarean delivery. PAS is an heterogeneous condition associated with a high maternal morbidity and mortality rate, presenting unique challenges in its diagnosis and management. Objective: This study aims to compare between the role of Transabdominal ultrasound vs Transvaginal ultrasound in assessment of placental invasion in cases of placenta previa anterior wall with previous uterine scar applying the unified descriptors of the "EW-AIP" and also to evaluate the sensitivity and specificity of each criterion by comparing them with the final outcome of pregnancy. Patients and methods: This study was conducted on (50) pregnant women diagnosed as placenta previa by ultrasonography and were candidates for repeated elective CS or elective hysterectomy (if the diagnosis of placenta accreta is confirmed). All of those patients presented during the period of December 2018 till August 2020 to El-sheikh Zayed Specialized Hospital Obstetrics outpatient clinic during their follow up visits in the 3rd trimester. Results: Combined gray-scale ultrasonography and color Doppler increased   the accuracy for diagnosis of placenta accreta to 100% as approved intra-operatively and by the histopathological examination. In our study: As regards the analysis of gray-scale ultrasonographic criteria, loss of the hypo-echoic retroplacental sonolucent zone has the highest percentage among the studied group (87.5%), followed by presence of abnormal placental lacunae (79.2%) then thinning or disruption of hyperechoic serosa – bladder interface and the presence of focal exophytic masses invading the urinary bladder (41.7%), (25%) respectively. Conclusion: Combined gray-scale ultrasonography and color Doppler ultrasound are suggested for all patients with placenta previa and pervious CS to find out the features which suggest presence of placenta accreta, and this allows the surgical team to plan ahead of each case individually according to the variable morphological and vascular patterns.