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a Chapter 19 Doppler Velocimetry and Hypertension 305
Fig. 19.2. Different flow velocity waveforms of the umbilical artery. a Normal end-diastolic flow. b Reduced end-diastolic
flow. c Absent end-diastolic flow. d Reversed flow
Fetal Assessment in Hospital
As abruptio placentae caused 36% of intrauterine
deaths in patients with early onset severe pre-eclampsia
[72] frequent fetal heart rate monitoring has been
introduced [73]. Many intrauterine deaths from
ªabruptio placentaeº are now being prevented as it
has been shown that abnormal fetal heart rate patterns
preceded the clinical diagnosis in the majority
of cases. For these reasons there is a limited place for
the use of umbilical artery flow velocity waveforms in
the daily assessment of patients hospitalized for severe
pre-eclampsia.
When Should the Patient Be Delivered for
Severe Pre-eclampsia?
Although there is some controversy about the timing
of delivery in patients with severe pre-eclampsia, researchers
at Tygerberg Hospital believe fetal outcome
could be improved in many cases by expectant management.
Rather than delivering for pre-eclampsia as
such, patients are only delivered for specific maternal
or fetal indications [41, 42, 74]. It has also been demonstrated
that delivery can be postponed in patients
with early onset severe pre-eclampsia. This enables
one to achieve a relatively low perinatal mortality rate
in patients with early onset severe pre-eclampsia [41,
42].
Severe pre-eclampsia necessitating admission to
hospital between 24 and 27 weeks' gestation was
studied in 39 women. By expectant management, gestation
was prolonged with a median of 12 days (range
3±47 days). Overall perinatal loss was 26% and neonatal
loss only 17%. Unless for a specific maternal or
fetal reason, termination of pregnancy or very early
delivery is not always indicated in these patients.
They should therefore, after informed consent has
been obtained, be given the opportunity to have expectant
management, provided that there is not reversed
or absent flow (Fig. 19.2) [43, 44].
Abruptio Placentae
The frequency of abruptio placentae in mothers admitted
for severe pre-eclampsia is 18%±20% [41, 42,
92]. It is therefore essential to assess whether the patient
with severe pre-eclampsia, at risk for this complication,
can be identified. In a case-controlled study
[75], 69 patients with severe pre-eclampsia who had
developed abruptio placentae were compared with the
same number of patients, matched for gestational age,
who did not develop abruptio placentae. Absent enddiastolic
flow velocity and a resistance entry above
the 95th percentile were seen in 7 and 31%, respectively,
of patients who did not develop abruptio placentae,
and in 1 and 23% of patients who developed
abruptio placentae. Abnormal umbilical artery Dop-