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Faculty have requested this content not be shared on social media
CME Credit Offered
CME Credit Offered
Abstract Award
Abstract Award
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Poster Session 3

(774) Sonographic features of placenta accreta spectrum with and without placenta previa

Friday, January 31, 2025
10:30 AM – 12:30 PM  
Objective: To evaluate sonographic features of placenta accreta spectrum (PAS) with placenta previa compared to those without placenta previa.

Study Design: Prospective, single referral center study of pregnancies undergoing a standardized, ultrasound protocol for PAS risk assessment in the second and third trimesters. Protocol was applied to pregnancies with placenta previa or request of the obstetric provider based on risk factors. Transvaginal ultrasound was performed if placenta previa was present. Loss of hypoechoic zone (LHZ), retroplacental myometrial thinning (RMT), placental lacunae (PL), placental extension (PE), hypervascularity (HV) and overall PAS risk were assessed. Delivery at >23 weeks gestation from 1/1/2023 to 7/15/2024 with clinical and/or histologic PAS were included. PAS with placenta previa (PAS-PP) included those with placenta covering the cervical os at the time of delivery. PAS without placenta previa (PAS-NP) excluded those with low-lying placenta even if they resolved.

Results:

Two hundred nineteen patients underwent the PAS ultrasound protocol and 37 diagnosed with PAS, 24 PAS-PP and 13 PAS-NP. PAS-NP was more likely than PAS-PP to have history of PAS (38% vs 0%, p < 0.01) and less likely to have LHZ, RMT, and HV. There was also a difference in number and size of PL. PAS-PP was more likely to have sonographic suspicion for PAS (78% vs 33%, p=0.02) with a PPV and NPV of 76% and 82%, respectively. Among PAS-NP, PPV and NPV was 44% and 81%, respectively. Twenty-three cases were non-invasive, 10 PAS-PP (42%) and 13 PAS-NP (100%). Sonographic suspicion for PAS was noted in 60% PAS-PP and 33% PAS-NP in the non-invasive subgroup, however, we were not powered to detect a difference (p=0.39).

Conclusion: Standard ultrasonographic signs of PAS are less likely to be present in PAS without placenta previa resulting in lower detection rates. Larger studies are needed to determine whether these differences persist in non-invasive PAS. Alternative PAS risk assessment tools should be investigated in non-previa PAS to improve antenatal detection.