Validation of a sonographic checklist for the detection of histologic placenta accreta spectrum by Gatta, LA, Ellestad, SC, Boyd, BK, Collins, S, Einerson, BD, Stephenson, ML, Hammad, I, Varvoutis, MS, Honart, AWEST, Federspiel, JJ, Craig, AM, Swartz, A, Salinaro, JR, Unnithan, S, Weber, J, Erkanli, A, Gilner, JB