GE Medical Systems 500, User Manual, Page: 274 / 636

OB Measurements and Formulas
LOGIQ 500 Basic Users Manual
2276612–100 Rev. 0
9–12

USA Method (cont’d)
Calc
Mnemonic Calc Name
Formula
Author
Reference
CUA** Composite
Ultrasound
Age 1. CUA(BPD)=9.54+1.482*(BPD)+0.1676*(BPD)^2
2. CUA(HC)=8.96+0.540*(HC)+0.0003*(HC)^3
3. CUA(AC)=8.14+0.753*(AC)+0.0036*(AC)^2
4. CUA(FL)=10.35+2.460*(FL)+0.170*(FL)^2
5. CUA(BPD,AC)=9.57+0.524*(AC)+0.1220*(BPD)^2
6. CUA(BPD,HC)=10.32+0.009*(HC)^2+
1.3200*(BPD)+0.00012*(HC)^3
7. CUA(BPD,FL)=10.50+0.197*(BPD)*(FL)+
0.9500(FL)+0.7300*(BPD)
8. CUA(HC,AC)=10.31+0.012*(HC)^2+0.3850*(AC)
9. CUA(HC,FL)=11.19+0.070*(HC)*(FL)+0.2630*(HC)
10. CUA(AC,FL)=10.47+0.442*(AC)+0.3140*(FL)^2–
0.0121*(FL)^3
11. CUA(BPD,AC,FL)=10.61+0.175*(BPD)*(FL)+
0.2970*(AC)+0.7100*(FL)
12. CUA(HC,BPD,FL)=11.38+0.070*(HC)*(FL)+
0.9800*(BPD)
13. CUA(HC,AC,FL)=10.33+0.031*(HC)*(FL)+
0.3610*(HC)+0.0298*(AC)*(FL)
14. CUA(HC,AC,BPD)=10.58+0.005*(HC)^2+
0.3635*(AC)+0.02864*(BPD)*(AC)
15. CUA(BPD,HC,AC,FL)=10.85+0.060*(HC)*(FL)+
0.6700*(BPD)+0.1680*(AC)
Unit: CUA (week), BPD (cm), HC (cm), AC (cm), FL (cm)
Hadlock,
Radiology, 1984
152:497–501
FL/AC FL/AC ratio FL/AC Hadlock, AJR
141:979, 1983
FL/HC FL/HC ratio FL/HC Hadlock, JUM 3:439,
1984
FL/BPD FL/BPD ratio FL/BPD Hadlock, AJOG
141:759, 1987
CI Cephalic
Index BPD/OFD short distance HC/long distance HC Hadlock, AJR 137:83,
1981
HC/AC HC/AC ratio HC/AC Campbell, BRJ.OG
84:165,1977
** Formulas are used only if Hadlock HC, FL, AC and BPD are used and the “CUA/AUA
for Hadlock” preset, found on System Parameters page 3, is set to “CUA”. If other
authors are used, CUA automatically changes to AUA and an average value is displayed.
Table 9–4. OB Calculation Formulas Part 2—USA Version Factory Defaults