RT Book, Section A1 Toy, Eugene C. A1 Jeanty, Philippe A2 Fleischer, Arthur C. A2 Toy, Eugene C. A2 Lee, Wesley A2 Manning, Frank A. A2 Romero, Roberto J. SR Print(0) ID 1106704351 T1 FETAL BIOMETRY T2 Sonography in Obstetrics and Gynecology: Principles & Practice, 7e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 9780071547727 LK obgyn.mhmedical.com/content.aspx?aid=1106704351 RD 2024/03/29 AB DefinitionsBiometry: measurements of fetal somatic structures in an attempt to construct the gestational age.Biparietal diameter: transverse diameter of the fetal skull from the leading edge (outer edge) of the near field to the leading edge to the far field (inner edge of skull), through the transthallamic plane.Abdominal circumference: a measure along the outer perimeter of the fetal abdomen in a true transverse plane at the level of the junction of the umbilical vein and the hepatic vein.Dolichocephaly: abnormally shaped fetal head that is "flatter."Brachycephaly: abnormally shaped fetal head that is more round in shape.Cephalic index: the ratio of the biparietal diameter and the occipital frontal diameter. This index allows one to determine whether the fetal head is of normal shape, dolichocephalic, or brachycephalic.