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Ultrasound/Imaging

Poster Session 4

(1126) The Placenta Accreta Index: Potential cutoffs for clinical management

Wednesday, February 14, 2024
1:00 PM – 2:30 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: The placenta accreta index (PAI) is a standardized method for the ultrasound (US) prediction of placenta accreta spectrum (PAS). Since 2019, we have prospectively applied the PAI in pregnancies in the second and third trimester identified to be at risk for PAS due to prior history of cesarean and placenta previa or low-lying placenta or other sonographic signs of PAS. We sought to determine clinically meaningful cutoffs to guide the decision to obtain adjunct magnetic resonance imaging (MRI).

Study Design: We analyzed pregnant individuals who underwent assessment with the PAI from 2019-2023. The last PAI prior to delivery was analyzed for prediction of hysterectomy. Two cut off values were determined for a 96% sensitivity and specificity for the outcome of cesarean hysterectomy. Associated sensitivity, specificity, positive predictive and negative predictive values were determined.  

Results: Of 126 with a PAI in the third trimester, 45/126 (36%) required a hysterectomy at delivery. PAI was performed at a mean gestational age of 31.2 ± 2.6 weeks. Mean gestational age at delivery was 36.8 ± 2.0 weeks. The cutoff value for a sensitivity of 96% for cesarean hysterectomy was a PAI of 3.5. The cutoff value for a specificity of 96% for cesarean hysterectomy was a PAI of 8.  

Conclusion: Our proposed cutoffs of 3.5 and 8 can provide excellent sensitivity and specificity respectively for predicting hysterectomy. The PAI range of 3.5 to 8 was indeterminate, with potential added value of MRI. Future studies will explore the value added of MRI within this PAI range.