title: A study of four methods of placental localization.
mesh_terms: D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008722:Methods; D010920:Placenta / Q000000981:diagnostic imaging; D010922:Placenta Diseases / Q000175:diagnosis; D010923:Placenta Previa / Q000175:diagnosis; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis; D011859:Radiography; D011877:Radionuclide Imaging / Q000295:instrumentation; D014463:Ultrasonography