Background: Placenta accreta is a severe pregnancy complication causing postpartum hemorrhage, bladder injury, and peripartum hysterectomy. Ultrasonography for antenatal diagnosis of PAS disorder has shown reduced maternal morbidity and death, making it crucial for management. This study determined the diagnostic value of ultrasound for the antenatal diagnosis of placenta accreta spectrum in women with placenta previa. Methods: This prospective observational study was conducted in the Department of Obstetrics and Gynaecology of Dhaka Medical College from June 2022 to May 2023. Forty pregnant women with placenta previa attending the outpatient section were included. Patients underwent ultrasound to assess the placenta and diagnose placenta accreta spectrum. Patients were followed until delivery. Pregnancy outcomes and perioperative diagnoses were observed or obtained from hospital records. Results: The mean age was 30.58 ± 3.82 years, with the majority of participants aged 30–40 years. About 52.5% had parity ≥3, 60% had cesarean section ≥2, and 20% had previous placenta previa. A significant link existed between parity (≥3), cesarean history (≥2), age (≥32 years), and preoperative PAS diagnosis. Ultrasonography showed that 72.5% had a placenta accreta spectrum, while intraoperative findings showed 80%. Among PAS cases, placenta increta (40.6%) and percreta (40.6%) were most common, followed by accreta (18.8%). In management, 87.5% underwent peripartum hysterectomy, and 21.5% had bladder injury repair. Based on perioperative identification, USG showed 84.38% sensitivity, 75.00% specificity, and 82.50% accuracy. Conclusion: Eighty percent of participants had placenta accreta syndrome. PAS was linked with age over thirty-two, higher parity, and multiple cesarean sections. Most needed peripartum hysterectomy, and one-fifth required bladder repair. Antenatal ultrasonography is a feasible diagnostic tool with sufficient accuracy that may reduce peripartum complications.