o_1977r8vv9vk1ts2ms0kd8pksa.pdf

368 D. Maulik, R. Figueroa
there were no indications that these fetuses underwent
adequate surveillance after the abnormal Doppler
findings, as up to 6 weeks transpired between
the abnormal findings and the fetal death. There is
an important methodologic issue related to the Doppler
examination technique. The high-pass filter,
which screens out low frequency components of the
Doppler signal, was set at 200 Hz, thereby increasing
the odds of a false-positive diagnosis of an absent
end-diastolic velocity. Regrettably, such an inappropriately
high setting of the high-pass filter has been
used by many other investigators, which may have
compromised the validity of their results. Despite
these limitations, the main finding that Doppler insonation
of the umbilical arteries may not be efficacious
in a low-risk population has been corroborated
by others [16±18].
Hanretty and coworkers [16] investigated the association
between the uteroplacental and umbilical arteries
and the obstetric outcome in unselected pregnant
mothers. Only the results of the umbilical Doppler
studies are discussed here. Their study utilized a
prospective blind design and the populations of 326
women at 26±30 weeks' gestation and 356 women at
34±36 weeks' gestation. There was a significant
(p