GE Medical Systems LOGIQ 7 Reference Manual page 118

Measurement Formulas
Formulas–OB
Calc
Mnemonic Calc Name
AC Abdominal
Circumference
BPD Biparietal
Diameter
CRL Crown Rump
Length
FL Femur Length
GS Gestational Sac
HC Head
Circumference
HC Head
Circumference
EF Ejection
Fraction
2 4
-
Table 2-4: OB Calculation Formulas
Input
Measurements
circumference by
trace, ellipse, circle
or two distances
one distance
one distance
one distance
three distances
circumference by
trace, ellipse, circle
or two distances
one ellipse
two distances on M-
Mode (End-diastolic
dimension and End-
systolic dimension
on M-Mode)
LOGIQ 7 Advanced Reference Manual
Formula
AC=13.3+1.61 (GA) -
2
0.00998 (GA)
BPD = -3.08+0.41 (GA) -
3
0.000061 (GA)
CRL=1.684969+
0.315646xd1+
0.049306xd1^2+
0.004057xd1^3+
0.000120456xd1^4
FL = -3.91 + 0.427 (GA) -
2
0.0034 (GA)
GS [wk] = 1.42450142 *
(d1+d2+d3)/3+ 3.6225
HC=-11.48 + 1.56 (GA) -
3
0.0002548 (GA)
HC [mm] = 2.325 * (BPD
[mm]^2 + OFD [mm]^2)^0.5
EF = (1 - Ds^3 / Dd^3)
Direction 2392205-100 Rev. 1
Author
Reference
Hadlock et al,
Radiology,
152:497-501,
1984
Hansmann,
Ultrasound
Diagnosis in
Obstetrics and
Gynecology,
438-9, 1985
n/a