Standardized ultrasound signs might prove useful for prenatal screening of women at risk of PAS disorders and should enable remote evaluation of images when PAS is suspected.

Objective To evaluate the impact of a training program using a systematic protocol on ultrasound signs of placenta accreta spectrum (PAS). Methods Intra‐ and inter‐observer variability rates and sensitivity were tested, before and after additional training, by two research fellows with a prior basic training in obstetric ultrasound using digitally recorded second‐trimester ultrasound images from cases of anterior placenta previa with and without PAS. Results Fifty‐two cases of anterior placenta previa with PAS (n=26) and without PAS (n=26) were included in the study. The highest level of inter‐observer agreement for ultrasound signs was found for the absence of placental bulge and/or focal exophytic mass on gray‐scale imaging and the absence of subplacental hypervascularity, bridging vessels and lacunar feeder vessels on color Doppler imaging. The level of inter‐observer agreement increased from 39% before training to 40% after training; the numbers agreed as PAS by both trainees increased from four to 20. No cases were classified as inconclusive after training. There was a significant (P<0.001) change in sensitivity for both trainees after training. Conclusion Additional training in detecting the ultrasound signs associated with PAS using a standardized protocol improves the diagnostic accuracy of operators with only a basic obstetric ultrasound training.

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