Background: Sonography has proven to be a useful modality to determine abnormalities related to the lower uterine segment (LUS) (such as placenta previa or weak previous cesarean section scar). Objective: To compare the accuracy of transvaginal ultrasound versus transabdominal ultrasound in assessment the lower uterine cesarean scar thickness at term, and compare them with actual intraoperative LUS thickness. Patients and methods: This prospective observational study included one hundred forty seven pregnant women who have history of previous scar. All cases were selected from Obstetrics and Gynecology Department at Al-HusseinHospital, Al-AzharUniversity, during the period from January 2021 to July 2021. Result: LUS thickness detected by TAS (transabdominal sonography) was significantly higher than LUS thickness detected by TVS (transvaginal sonography). LUS thickness detected by TAS was significantly higher than LUS thickness detected intraoperatively, and LUS thickness detected by TVS was significantly higher than LUS thickness detected intraoperatively. Conclusion: The LUS scar thickness measurement was most accurate with TVS in comparison with TAS. Ultrasonography evaluation permited better assessment of the risk of intrapartum complications for patients attempting VBAC (vaginal birth after cesarean section), and could allow for safer management of delivery.