A Primary Screening Predictive Model for Abnormally Invasive Placenta Based on Clinical and Basic Ultrasound Factors in Singleton Pregnancies.

OBJECTIVES: This study investigated risk factors for abnormally invasive placenta (AIP) in singleton pregnancies and developed a risk prediction model using clinical and basic ultrasound features for AIP screening. METHODS: A retrospective analysis was conducted on 16,735 singleton pregnancies (with/without AIP) delivering at the First Affiliated Hospital of Sun Yat-sen University (2017-2021). Eighteen clinical and 3 basic ultrasound features were recorded. AIP was confirmed via placental pathology or intraoperative observations. The cohort was randomly split into development (70%) and validation (30%) sets. Univariate/multivariate logistic analyses and multicollinearity tests identified AIP predictors. Three models (clinical-only, basic ultrasound-only, combined) were constructed; their performances were compared to select the final model, visualized as a nomogram. Model performance was evaluated using receiver operating characteristic curves (ROC), area under the curves (AUC), calibration curves, and decision curve analysis (DCA) (1000 bootstraps, 5-fold cross-validation). RESULTS: AIP was confirmed in 161 cases (0.962%). Independent predictors included a history of placenta accreta spectrum (PAS), advanced maternal age, assisted reproductive technologies (ART), pre-pregnancy obesity, placenta previa/low-lying placenta, and placental location (p < 0.05). In the validation set, the combined model had an AUC of 0.844 (95% CI 0.775-0.913), versus 0.781 (95% CI 0.701-0.862) for basic ultrasound-only and 0.698 (95% CI 0.626-0.770) for clinical-only. The nomogram of the combined model showed good discrimination; calibration curves and DCA confirmed satisfactory calibration and clinical utility. CONCLUSION: The combined clinical-basic ultrasound model outperforms single-component models in AIP prediction. Its nomogram has good predictive performance, enabling clinicians to quickly screen high-risk pregnant women for AIP.