AbstractObjectiveTo evaluate the role of the placenta accreta index (PAI) score in predicting placenta accreta spectrum (PAS).MethodsIn this prospective study, the PAI was applied to 100 third‐trimester pregnant women with at least one previous cesarean delivery (CS) and anterior low‐lying placenta or placenta previa. PAI score was calculated based on placental location, number of CS, abnormal placental lacunae, sagittal smallest myometrial thickness (SSMT), and bridging vessels. Histopathologic confirmation was obtained if hysterectomy was performed. Outcome measures were area under the receiver–operating characteristics curve (AUC‐ROC) and the best cut‐off point of PAI. Regression analysis of the PAI parameters was performed.ResultsThe PAI had an AUC of 0.84 (95% confidence interval [CI] 0.75–0.91). The best cut‐off point of PAI was 5.37, with a sensitivity of 83.9%, a specificity of 76.3%, a positive predictive value of 85.2%, a negative predictive value of 74.3%, and an accuracy of 81%. PAI parameters showed a significant association with histopathologically proven PAS (n = 23). The highest odds ratio (OR) was achieved with lacunae grades 2 and 3 (OR 9.22, 95% CI 2.02–42) and the lowest OR with SSMT <1.5 mm (OR 3.78, 95% CI 1.3–10.6).ConclusionThe PAI appears to be a promising predictor of PAS in high‐risk women who required hysterectomy.