GE LOGIQ 500 Advanced Reference Manual page 198

Bioeffects
Summary
Suggested Guidelines
Overview
6–14
It is important to realize that current investigation DOES NOT
support the concept that Doppler waveform analysis in the
above obstetrical conditions provides information that is meant
to replace other conventional tests, or the biophysical profile,
also, it should not replace classical non-Doppler ultrasound
scanning methods. Rather, it appears that Doppler is of value
when used in conjunction with these other tests. Lastly, there is
little data to suggest that an isolated Doppler examination of the
fetus can be used as a screening tool in a low
identify the compromised fetus.
As with the evolution of any new diagnostic technique, the
indications for use may change when new experimental data
become available.
Following are suggested guidelines prepared by Harold
17
Schulman, M.D
There are two types of Doppler instruments, continuous wave
(CW) and pulsed. Modern instruments use directional Dopplers,
that is they portray forward and reverse flow on a split screen.
The CW Doppler transverses the entire vessel diameter and
summarizes a variety of reflections, including those from the
vessel wall and neighboring vessels. The pulsed Doppler is
focused and may sample the red cell flow in different loci within
the radius, but has the advantage of rejecting extraneous
signals from other vessels. Its disadvantage is in that some
current instrumentation utilize output energies which exceed
guidelines for safety on obstetric ultrasound.
LOGIQ 500 Advanced Reference Manual
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risk population to