o_1977r8vv9vk1ts2ms0kd8pksa.pdf

striction or hypertensive disease of pregnancy would
the use of Doppler velocimetry reduce the number of
perinatal deaths and unnecessary obstetric interventions.
Two other meta-analyses of trials of umbilical artery
velocimetry in low-risk pregnancies have been
performed. Goffinet and colleagues [30] conducted a
meta-analysis of four randomized trials of umbilical
Doppler in unselected or low-risk pregnancies with a
total population of 11,375 women. Three other studies
were not included because they did not meet the inclusion
criteria or they had methodological problems.
Screening Doppler umbilical artery velocimetry did
not influence perinatal deaths (overall perinatal
deaths OR 0.90, 95% CI 0.50±1.60) or stillbirth (overall
stillbirths OR 0.94, 95% CI 0.42±1.98), antenatal
hospitalization (OR 1.04, 95% CI 0.95±1.15), obstetric
outcome, or perinatal morbidity.
A subsequent meta-analysis of five trials on routine
Doppler ultrasound in unselected and low-risk
pregnancies with a total population of 14,338 women
also concluded that routine Doppler ultrasound examination
in low-risk or unselected populations did
not confer benefit on mother or infant [31]. Umbilical
Doppler examination cannot be recommended as a
routine test in low-risk or unselected populations.
Unfortunately, the many systematic reviews of
trials on the effect of umbilical artery Doppler velocimetry
have been based on essentially the same 12
trials that were evaluated in the first meta-analysis by
Alfirevic and Neilson [26] with some modifications.
Thornton has been critical of this pattern of repeated
analysis, and believes that ªrepeated analysis of the
same data set can at best only generate hypotheses
for future researchers to testº [49]. He suggested the
need for trials of the effect of umbilical artery Doppler
velocimetry where there is a clearly defined
group and a defined delivery timing policy to follow.
Alternatively, trials with well-defined groups and different
delivery timing policies should be addressed.
It is of interest to note that none of the existing
modalities of fetal surveillance are based on affirmative
evidence derived from clinical trials and systematic
meta-analytic reviews. The benefit of the antepartum
nonstress test was investigated in four randomized
clinical trials [50±53]. None of the studies demonstrated
any benefit. Moreover, a meta-analysis of
these studies failed to show any benefit (Table 26.5).
No randomized trial has ever been reported for the
contraction stress test. There were two quasi-randomized
trials on the fetal biophysical profile in the 1980s
[55, 56]; neither demonstrated any difference in outcome
after use of the test. Subsequent meta-analytic
review also showed no benefit [57]. Two additional
trials [58, 59] on the biophysical profile published in
the 1990s were included in the meta-analysis by Ala
Chapter 26 Doppler Velocimetry for Fetal Surveillance: Randomized Clinical Trials and Implications for Practice 397
Table 26.4. Meta-analysis of Doppler randomized clinical
trials performed on high-risk pregnancies utilizing the random
effects model of DerSimonian and Laird [44]. The
analysis shows the effect on perinatal mortality
First author Doppler Control Odds Ratio
(95% CI)
Trudinger, 1987 1/127 5/162 0.25 (0.03±2.16)
McParland, 1988 6/254 20/255 0.28 (0.11±0.72)
Tyrrell, 1990 3/250 3/250 1.00 (0.20±5.00)
Hofmeyr, 1991 4/438 8/459 0.52 (0.16±1.74)
Newnham, 1991 9/275 9/270 0.98 (0.38±2.51)
Burke, 1992 4/241 3/235 1.31 (0.29±5.90)
Almstrom, 1992 0/214 3/212 0.14 (0.01±2.72)
Biljan, 1992 1/338 4/336 0.25 (0.03±2.22)
Johnstone, 1993 12/1,132 16/1,197 0.79 (0.37±1.68)
Pattinson, 1994 6/108 8/104 0.71 (0.24±2.11)
Neales, 1995 11/236 14/231 0.76 (0.34±1.71)
Nienhuis, 1995 2/74 3/76 0.68 (0.11±4.17)
Total 59/3,687 96/3,787 0.64 (0.46±0.90)
CI 0.50±1.01) especially in pregnancies complicated
by hypertension or presumed impaired fetal growth.
In addition, there were fewer inductions of labor (OR
0.83, 95% CI 0.74±0.93) and fewer hospital admissions
(OR 0.56, 95% CI 0.43±0.72) without adverse
perinatal effects. Moreover, there was no difference
for fetal distress in labor (OR 0.81, 95% CI 0.59±1.13)
or cesarean deliveries (OR 0.94, 95% CI 0.82±1.06).
The investigators concluded that the use of Doppler
ultrasound appeared promising in helping to reduce
perinatal deaths.
Westergaard and colleagues [29] reanalyzed randomized
controlled trials on the use of umbilical artery
Doppler velocimetry in 8,633 high-risk pregnancies
in order to determine which high-risk pregnancies
benefit from the use of Doppler velocimetry.
They divided 13 randomized controlled trials (including
two unpublished studies) into ªwell-defined studies,º
when there was a strict definition of suspected
intrauterine growth restriction or hypertensive disease
of pregnancy, and ªgeneral risk studies.º The
ªwell-defined studiesº showed a significant reduction
in antenatal admissions (OR 0.56, 95% CI 0.43±0.72),
inductions of labor (OR 0.78, 95% CI 0.63±0.96), elective
deliveries (OR 0.73, 95% CI 0.61±0.88), and cesarean
deliveries (OR 0.78, 95% CI 0.65±0.94). No significant
difference was found in perinatal mortality
(OR 0.66, 95% CI 0.36±1.22). The perinatal deaths
were audited by a panel of 32 international experts
who found that more perinatal deaths in the ªwell-defined
studiesº were potentially avoidable by use of
Doppler velocimetry (50% controls versus 20% Doppler
velocimetry group). The ªgeneral risk studiesº
did not show significant differences in the variables
studied. These investigators concluded that only in
pregnancies with suspected intrauterine growth re-