Due to the increased rate of cesarean sections in the last decades, the anomalies of placental implantation and invasion have become an emerging pathology. Undetected prenatally, severe forms of invasive placentation can lead to dramatic consequences such as a uterine rupture in labor, peripartum hemorrhage, necessity of hysterectomy and massive blood transfusions. That is the reason why the prenatal diagnosis of impaired placentation plays a key role to detect patients at risk, who should be referred to tertiary perinatal centers. If the diagnosis of abnormal placentation is confirmed, the next step should be to define the degree of placental invasion. Twodimensional ultrasonography (2D-US) is the technique mainly used to diagnose the placenta accreta spectrum (PAS), but its accuracy could be possibly increased by the complementary use of the three-dimensional (3D) US and 3D power Doppler. Only a few prospective studies are available on the role of 3D US in the detection of PAS without establishing objective, universally acceptable ultrasonographic diagnostic criteria. Moreover, diagnosis is subjective with accuracy depending on the experience of the operator. 3D power Doppler technique seems to have a good intraoperator but low interoperator reproducibility, because it needs a rigorous standardization of predetermined machine settings. Multicentric studies are needed to identify common and objective 3D US and 3D power Doppler diagnostic criteria for PAS, to reduce interoperator variability.