Special report of the society for maternal-fetal medicine placenta accreta spectrum ultrasound marker task force: consensus on definition of markers and approach to the ultrasound examination in pregnancies at risk for placenta accreta spectrum - Shainker, S A; Coleman, B; Timor-Tritsch, I E; Society for Maternal-Fetal Medicine. Electronic address: pubs@smfm.org (Am J Obstet Gynecol, 2021)