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236 E.R. Guzman et al.
normal finding until week 26 of gestation. Later, Thaler
et al. [37] identified a group of women who had
both systolic and diastolic notches in the uterine artery
waveform and demonstrated that perinatal outcome
was worse than when there was a diastolic
notch only (Fig. 16.13). Retention of the early diastolic
notch is thought to represent persistence of the inherent
total high impedance of the uterine artery circulation.
It has been identified in waveforms of the
main uterine artery and its most proximal branches.
Fleischer et al. [36] were the first to note the importance
of the uterine notch in their study of 71
women with hypertensive disorders of pregnancy.
Ninety percent (27 of 30) of women who developed
preeclampsia or chronic hypertension with superimposed
preeclampsia had a uterine waveform notch.
When normal pregnancy outcome was defined as delivery
at 37 weeks or later or a birth weight of 2500 g
or more, the uterine artery notch had better sensitivity
(93%), specificity (91%), positive predictive value
(87%), and negative predictive value (95%) compared
to the mean arterial blood pressure, creatine clearance,
uric acid level, and uterine S/D ratios.
Thaler et al. [37] evaluated a group of 140 hypertensive
pregnant women. Of 39 women with diastolic
or systolic notches (or both) in the uterine artery
waveform, 82% (32 of 39) had pregnancy-related hypertensive
complications. Hypertensive women with
uterine systolic and diastolic notches had higher
waveform indices of both uterine and umbilical arteries,
higher diastolic and systolic blood pressures,
and worse perinatal outcomes than those without
notches (Tables 16.1 and 16.2). When umbilical artery
resistance was normal and both uterine arteries had
elevated resistance indices, the group with the uterine
waveform notch had worse perinatal outcomes (Table
16.3). When the uterine artery and umbilical artery
waveforms were abnormal, the presence of the
Fig. 16.13. Subplacental (top), right uterine (bottom left),
and left uterine (bottom right) waveforms in a chronically
hypertensive pregnant woman at 22 weeks' gestation. Both
uterine arteries have systolic and diastolic notches. The placenta
was central and posterior. At 26 weeks' gestation she
presented with a fetal demise after an arrest of fetal
growth at 19 weeks