The unknowns of ultrasound.
D005260:Female; D006745:Hospital Bed Capacity, 300 to 499; D006748:Hospital Departments; D006801:Humans; D009775:Obstetrics and Gynecology Department, Hospital; D011247:Pregnancy; D011258:Pregnancy Tests; D014465:Ultrasonics / Q000295:instrumentation*; D014463:Ultrasonography; D014481:United States