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a Chapter 16 Doppler Velocimetry of the Uteroplacental Circulation 249
The results of these studies are best summarized
by the work of Ducey and colleagues [86], who classified
hypertension according to four vascular patterns
(Table 16.9). The most common vascular pattern in
hypertensive pregnancies is defined by normal uterine
and umbilical velocimetry. Although most of these
women had chronic hypertension, preeclampsia and
pregnancy-induced hypertension also occurred with
this pattern. Regardless of the clinical diagnosis, the
perinatal outcome was similar to that of a normal obstetric
population. These data support optimal medical
management of hypertensive women who display
this velocimetry pattern rather than aggressive intervention
for fear of fetal risk.
The next most common category was abnormal
uterine and umbilical artery velocimetry. The authors
hypothesized that this group lacks endovascular trophoblastic
invasion of the myometrial portion of the
subplacental spiral arteries. The women had the worst
perinatal outcome and accounted for all the perinatal
deaths in the study. They and their fetuses experienced
severe early disease. Most of the preeclamptic
women and a significant number of the women with
pregnancy-induced hypertension had this vasculopathy.
For optimal outcome these patients must be identified
early, and both mother and fetus require intensive
surveillance. The potential for early delivery is
great, with many requiring operative delivery. Consideration
should be given to using preventive or
modifying medication, such as aspirin.
The next two categories consisted of women with
isolated deficiencies of either the uterine arteries or
umbilical arteries. Surprisingly, the less common of
the two was abnormal uterine artery flow only. The
Doppler pattern of abnormal umbilical flow belies the
popular concept that the placental ischemia seen with
pregnancy hypertension is the result of poor maternal
perfusion. The perinatal outcome is poorer than
when there is abnormal uterine flow only. The fetus
is protected by the umbilical artery circulation, and it
adapts well to reductions in uterine artery flow. Guzman
et al. [108] also described pregnancy-induced
hypertension associated with abnormal umbilical
flow, only with greater consequences to the fetus than
the mother.
When viewing the results of all the observational
studies, a pattern emerges wherein abnormalities in
uterine artery flow correlate best with maternal complications.
Moreover, the state of the umbilical artery
circulation is more predictive than that of the uterine
artery circulation in terms of fetal-neonatal outcome.
Uterine artery Doppler velocimetry has been
shown to correlate very well with pregnancy outcome
in women with chronic hypertension. Caruso et al.
[109] studied 42 women with chronic hypertension
and showed increased incidences of preeclampsia
Table 16.9. Velocimetry for hypertension and pregnancy (reproduced from [86] with permission)
Parameter Normal flow velocity in uterine artery Abnormal flow velocity in uterine arery
NI. umb. (n=66) Abnl. umb. (n=27) NI. umb. (n=12) Abnl. umb. (m =31
Maternal data
Age (years) 29 Ô 7 27Ô6 24Ô7 27 Ô6
Nullipara (%) 57 52 80 63
MAP, 2nd trimester (mmHg) 97 Ô 12 95Ô13 105 Ô21 96 Ô21
Abnormal platelets (%) 0 26* 13 0
Uric acid (mg/dl) 5.6Ô1.1 6.5Ô2.2 6.0Ô1.4 6.5Ô1.5*
Proteinuria (%) 24 71** 75 ** 86 ***
Uterine artery S/D ratio 2 Ô0.3 2.1Ô0.3 3.4Ô9.0*** 4.1Ô1.5***
Fetal/neonatal data
Birth weight (g) 3,261 Ô522 2,098 Ô 811*** 2,464 Ô 722*** 1,627Ô697***
Gestational age (weeks) 39Ô2 35.7 Ô3.2*** 36.3 Ô3.0** 33.3 Ô2.7 ***
Delivery