RT Book, Section A1 Cunningham, F. Gary A1 Leveno, Kenneth J. A1 Bloom, Steven L. A1 Dashe, Jodi S. A1 Hoffman, Barbara L. A1 Casey, Brian M. A1 Spong, Catherine Y. SR Print(0) ID 1160772489 T1 Placental Abnormalities T2 Williams Obstetrics, 25e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781259644320 LK accessmedicine.mhmedical.com/content.aspx?aid=1160772489 RD 2024/04/18 AB The placenta, as a rule, presents more or less rounded outlines, but now and again when inserted in the neighbourhood of the internal os it may take on a horseshoe-like appearance, its two branches running partially around the orifice.—J. Whitridge Williams (1903)