Cesarean scar pregnancy as a precursor lesion for placenta accreta spectrum: evidence and implications

Cesarean scar pregnancy (CSP) is a form of abnormal implantation in which the gestational sac embeds within the myometrial defect of a previous cesarean incision. Its incidence is rising in parallel with increasing cesarean delivery rates. Emerging evidence indicates that CSP and placenta accreta spectrum (PAS) share common histopathological and sonographic characteristics, supporting the concept that CSP represents an early phenotype within the PAS.

To synthesize current evidence on the diagnosis, classification and management of CSP and to clarify the biological and clinical continuum linking CSP with PAS, with emphasis on early prediction and reproductive implications.

Early first-trimester targeted transvaginal ultrasonography, including assessment of residual myometrial thickness, implantation site, vascularity and standardized classification systems, remains central to diagnosis and risk stratification. Surgical approaches that incorporate scar resection via laparoscopy, laparotomy or transvaginal techniques demonstrate the highest success and lowest recurrence rates, as excision of scar tissue restores myometrial integrity. Other modalities such as suction curettage, hysteroscopy, local methotrexate, uterine artery embolization, balloon tamponade and high-intensity focused ultrasound show variable effectiveness depending on gestational age and CSP subtype. Expectant management may result in live birth, but it carries substantial risk because PAS develops in up to 80% of ongoing pregnancies and severe hemorrhage and hysterectomy are common. Shared pathological findings such as deficient decidualization, myometrial disruption and abnormal uteroplacental vascular remodeling support the concept that CSP and PAS represent a unified pathological spectrum rather than distinct entities.

CSP may represent an early phenotype within the PAS. Standardized terminology, early first-trimester screening and risk-based management strategies are essential to reduce maternal morbidity and optimize reproductive outcomes. Multicenter prospective studies are needed to guide evidence-based prevention and treatment strategies.