Abnormal placenta implantation. Integration between first- and third-trimester imaging in predicting the severity of Placenta Accreta Spectrum (PAS) disorders.

Placenta accreta spectrum (PAS) disorders are pathological conditions correlated to a high risk of adverse maternal surgical outcomes, especially if not diagnosed. In the last 10 years, the literature interest for prenatal diagnosis of PAS disorders has been noticeably greater. More recently, significant progression in prenatal imaging techniques permitted an increase of early identified cases and a more accurate diagnosis of these anomalies, especially in women with multiple risk factors. The aim of this chapter is to give an overhaul on prenatal diagnosis of PAS disorders throughout gestation and to report whether integration between first- and third-trimester ultrasound can predict the development and severity of these anomalies.