Imaging of Placenta Accreta Spectrum.

Placenta accreta spectrum (PAS) refers to an abnormally invasive implantation of the placenta into the uterine myometrium. The resultant risk is that of severe maternal hemorrhage and significant maternal morbidity and even mortality. The 2 strongest risk factors for the development of PAS are a history of a prior cesarean section and a placenta previa in the current pregnancy. Clinically, most patients are asymptomatic but some will present with vaginal bleeding and abdominal cramping. The goal of this article is to discuss the common clinical presentation and risk factors for placenta accreta spectrum, and to review in detail the ultrasound features/markers of PAS in each trimester.