The value of a simple sonographic screening test for placenta accreta spectrum prediction: A case-control study

Background Placenta accreta spectrum (PAS) represents life-threatening conditions; however, early diagnosis reduces complications and mortality rates. Aims To develop and evaluate the accuracy of a simple sonographic screening test for PAS prediction. Materials and Methods A retrospective case-control study of 481 women with singleton pregnancies at 28 weeks or later, with a scarred uterus or placenta praevia, who underwent sonographic testing for PAS detection during 2010-2020. We compared demographic and sonographic features, and delivery outcomes between women who were and were not confirmed to have a PAS condition at delivery. We evaluated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and predictive probability for the sonographic screening model. Results Among all the women with at least one sonographic sign (large lacunae or loss of clear zone), the odds ratio (OR) of PAS was 21.7 (95% CI, 16.7-70.4), among those with placenta praevia (and at least one sonographic sign), the OR was 41.9 (95% CI, 15.8-111). For the screening model (the combinations of placental location (major or minor placenta praevia) with at least one sonographic sign (large lacunae or loss of clear zone)), sensitivity, specificity, PPV, NPV and predicted probability were 94.9% (85.8-98.9%), 91.5% (88.4-93.9%), 60.9% (50.1-70.9%), 99.2% (97.7-99.8%) and 92.3%, respectively. Conclusions A combination of simple ultrasound signs for PAS screening may be highly effective for prenatal assessment and prediction of placenta accreta. This screening test can be carried out as routine pregnancy follow-up for women with risk factors for PAS.