Predicting Placenta Accreta Spectrum: Validation of the Placenta Accreta Index

Abstract

To the Editor: We wish to extend our thanks for the letter to the editor "Morbid Adherent Placenta Score: A simple and practical approach on application of Placenta Accreta Index" (PAI). It is encouraging to find that your application of our PAI yields excellent results. What is important to note is the added rigor of your study, which was prospective and showed perfect interobserver correlation. Also, it is agreed, based on our ROC curve, 5 or greater imposes a higher probability and may be used as a discriminatory value. Our validation paper gave each number on the scale (1-9) a given sensitivity and specificity, which is included in our US report, as rarely are clinical decisions of invasion strictly binary.Despite these findings of the multiparametric analysis of the PAI and other combined analytics, as you stated, the degree of invasion prediction is not currently obtainable and we need to offer more to obstetricians and gynecologic oncologists including not only depth of invasion, but the topographic distribution of invasion.We were intrigued by your 3D imaging and agree of its potential to provide better topography, particularly when coupled with power images.

Nanoparticle Contrast-enhanced MRI for Visualization of Retroplacental Clear Space Disruption in a Mouse Model of Placental Accreta Spectrum (PAS)

“…Because of the difficulties in diagnosis, the utility of MRI has been debated, with some experts advocating its utility in identifying topography and extent of invasion to optimize surgical planning [11], while others have questioned whether it falsely changes management. While both ultrasound and MRI have a reported sensitivity and specificity approaching or above 90% in expert centers [12][13][14], the overall rate of antenatal detection in multiple population-based studies is closer to 30-50% [7,15,16]. In cases of shallow or focal invasion, antenatal diagnosis is especially challenging, even in expert centers, highlighting the pressing need for improved antenatal diagnostic imaging.…”