Importance of placental evaluation in pregnancies at high risk for placenta accreta spectrum: Expert clinical perspective.

Background: Placenta accreta spectrum (PAS) is a leading cause of obstetric morbidity and peripartum hysterectomy. Rising cesarean delivery rates, advanced maternal age, and assisted reproductive technologies have increased its incidence. Early, standardized diagnosis is essential for multidisciplinary planning and improved outcomes, yet formal screening guidelines are lacking. Objective: To raise awareness of the importance of antenatal screening for PAS, summarize key clinical and imaging risk factors, and propose a standardized mid-trimester ultrasound protocol for high-risk patients. Methods: An expert panel convened under the Pan-American Society for the Placenta Accreta Spectrum (PAS2) reviewed available evidence, risk stratification models, and prior consensus statements to develop practical recommendations for PAS screening. Results: PAS risk rises with the number of prior cesarean deliveries, especially in the setting of concurrent placenta previa or anterior low-lying placenta. Combined transabdominal and transvaginal ultrasound using grayscale and low-flow color Doppler (<10 cm/s) best identifies characteristic markers such as loss of the clear zone, myometrial thinning, bladder-wall interruption, placental bulge, uterovesical hypervascularity, lacunae, and bridging vessels. Standardized imaging protocols and structured reporting improve detection and facilitate referral to specialized centers. Conclusions: All patients with placenta previa or low-lying placenta and prior cesarean delivery should undergo targeted PAS screening at the time of anatomic survey. Early, systematic assessment and referral improve safety and outcomes.