GE LOGIQ A100, Technical Publication

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OB User Table
212
LOGIQ
t α
100 User Manual
2211157–100 Rev 0
Choosing the Statistical Expression of Output (CGA) (continued)
Range (time)
This format displays the normal range of GA for a
particular obstetric measurement. It does not give
information on whether the fetus is normal for date or
not.
Percentile Score
The percentile score not only describes whether the fetus
is normal but also shows tangibly where exactly it stands
in a percentile ranking.
A percentile score of 50% is right in middle. A score
below 10
th
percentile is considered small for date and a
score above 90 is considered large for date.
Standard Deviation
This format gives the gestational age and the normalcy
of growth in statistical parlance. It expresses the
discrepancy between DGA and sonological
measurement in form of
‘number of times the standard
deviation (
s
times)’. A difference of up to 2 standard
deviations (2
s
) is considered normal.
s
times above 2 is
considered large for date and
s
times below 2 is
considered small for date as far as the particular
sonographic measurement is considered.
s
times is calculated using the formula:
s times +
x
table
–x
s
s
= standard deviation for DGA as in data sheet
x
table
is the data sheet value for DGA
x is the sonographically measured parameter