(253) Association of placenta accreta index with delivery timing in setting of placenta accreta spectrum

We aimed to assess the Placenta accreta index (PAI) score and its correlation with gestational age (GA) at delivery and risk of unscheduled deliveries for patients with suspected PAS.

Study Design:
Single center retrospective cohort of patients referred for suspected PAS who were evaluated and delivered at a large academic center between January 2023 – July 2025. Patients were included if they had ≥ 1 prior cesarean delivery and low-lying/ previa placentation. Sonographic images obtained in the third trimester were reviewed by 2 investigators. PAS was diagnosed if clinical evidence of invasion was seen at time of delivery or if any placental invasion was identified histologically. The primary outcome was the association between the PAI score and gestational age at delivery using spearman test, secondarily, we also evaluated the GA at the time of delivery and risk of unscheduled deliveries based on different PAI score groups using Kruskal-Wallis test and chi-square test, respectively.

Results:
Ninety patients with antenatal suspicion for PAS were identified. Seventy of them had pathologic confirmation of PAS. There was a significant negative association between PAI score and GA at delivery (Figure 1) (Spearman’s ρ = -0.221, p = 0.036). Unscheduled deliveries were significantly more frequent in higher PAI groups (p = 0.015) (Table 1). There was no significant difference in frequency of different reasons for unscheduled delivery among different PAI groups (p=0.595).

Conclusion:
Higher PAI scores were associated with earlier gestational age at delivery and an increased risk of unscheduled deliveries in patients with suspected PAS. These findings suggest that the PAI can be a useful tool for anticipating potential complications surrounding timing of delivery that may lead to modified management of those at highest risk of PAS to ensure optimal outcomes.