Letter: Value of ultrasonography in obstetrics.
D005260:Female; D006801:Humans; D010923:Placenta Previa / Q000175:diagnosis; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011271:Pregnancy, Ectopic / Q000175:diagnosis; D014463:Ultrasonography; D014592:Uterine Hemorrhage / Q000175:diagnosis*