ACOG practice patterns. Routine ultrasound in low-risk pregnancy. Number 5, August 1997. American College of Obstetricians and Gynecologists.
D000013:Congenital Abnormalities / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D011247:Pregnancy; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data