User guide

82 Measurement publications and terminology
EDD = LMP date + 280 days
Estimated Fetal Weight (EFW)
Hadlock, F., et al. “Estimation of Fetal Weight with
the Use of Head, Body, and Femur Measurements,
A Prospective Study.”
American Journal of
Obstetrics and Gynecology
, 151:3 (February 1,
1985), 333-337.
Hansmann, M., et al.
Ultrasound Diagnosis in
Obstetrics and Gynecology
. New York:
Springer-Verlag, (1986), 154.
Osaka University.
Ultrasound in Obstetrics and
Gynecology
. (July 20, 1990), 103-105.
Shepard M.J., V. A. Richards, R. L. Berkowitz, et al.
“An Evaluation of Two Equations for Predicting
Fetal Weight by Ultrasound.”
American Journal of
Obstetrics and Gynecology
, 142:1 (January 1,
1982), 47-54.
University of Tokyo, Shinozuka, N. FJSUM, et al.
“Standard Values of Ultrasonographic Fetal
Biometry.”
Japanese Journal of Medical Ultrasonics ,
23:12 (1996), 880, Equation 1.
Gestational Age (GA) by Last Menstrual
Period (LMP)
The gestational age derived from the LMP date
entered on the patient information form.
Results are displayed in weeks and days, and is
calculated as follows:
GA(LMP) = System date – LMP date
Gestational Age (GA) by Last Menstrual
Period (LMPd) Derived from Established
Due Date (Estab. DD)
Same as GA by Estab. DD.
The gestational age derived from the system
derived LMP using the Established Due Date
entered on the patient information form.
Results are displayed in weeks and days, and is
calculated as follows:
GA(LMPd) = System Date – LMPd
Last Menstrual Period Derived (LMPd) by
Established Due Date (Estab. DD)
Results are displayed as month/day/year.
LMPd(Estab. DD) = Estab. DD – 280 days
Gestational age tables
Abdominal Circumference (AC)
Hadlock, F., et al. “Estimating Fetal Age:
Computer-Assisted Analysis of Multiple Fetal
Growth Parameters.”
Radiology , 152: (1984),
497-501.
Hansmann, M., et al.
Ultrasound Diagnosis in
Obstetrics and Gynecology
. New York:
Springer-Verlag, (1986), 431.
University of Tokyo, Shinozuka, N. FJSUM, et al.
“Standard Values of Ultrasonographic Fetal
Biometry.”
Japanese Journal of Medical Ultrasonics ,
23:12 (1996), 885.
Biparietal Diameter (BPD)
Chitty, L. S. and D.G. Altman. “New charts for
ultrasound dating of pregnancy.”
Ultrasound in
Obstetrics and Gynecology
10: (1997), 174-179,
Table 3.
WARNING:
The gestational age calculated by
your SonoSite system does not
match the age in the
aforementioned reference at the
20.0 cm and 30.0 cm abdominal
circumference (AC)
measurements. The implemented
algorithm extrapolates the
gestational age from the slope of
the curve of all table
measurements, rather than
decreasing the gestational age for
a larger AC measurement indicated
in the referenced table. This results
in the gestational age always
increasing with an increase in AC.