OB Measurements and Formulas
LOGIQ 500 Basic Users Manual
2233658–100 Rev. 0
9–20
Amniotic Fluid Index (AFI)
The Amniotic Fluid Index is determined by taking distance
measurements of the 4 quadrants of the uterine cavity. These 4
measurements are added together to calculate the Amniotic
Fluid Index.
When all 4 quadrants have been measured, the AFI will be
calculated and displayed in the Calculation Result Area of the
display.
The normal values are considered to be:
36–40 weeks
0–5 cm = very low
5.1–8.0 cm = low
8.1 – 18.0 cm = normal
>18.0 = high
Dr. Rutherford/Dr. Phelan,
Obstetrics
and Gynecology, Volume 70, No. 3,
Part 1, p. 353–6, Sept. 1987.
28–40 weeks
15.0 cm = average
>20.0 – 24.0 = hydramnios
<5.0–6.0 = Oligohydramnios
Dr. C.C. Smith,
The Female Patient,
Volume 15, p. 85–97, March 1990.
Select AFI from the OB Measurement Soft Menu.
The skip function using the Ellipse rocker switch is not available
for AFI.
Unfreezing the image after doing an AFI measurement does not
delete the previous measurements. Unfreeze and change scan
planes as necessary. Make the remaining measurements to
arrive at the AFI value by following the basic distance
measurement procedure.
If any generic distance measurements are unassigned before
invoking the Amniotic Fluid Index these measurements will be
used. Only the remaining distance measurements need to be
made to arrive at an AFI.
Hints
Sagittal
Transverse
