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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018
392
AFRICA
beneficial effect of aspirin is a consequence of an improvement
in the transformation of uterine spiral arteries.
Masotti
et al
.
57
demonstrated a differential inhibition of cyclo-
oxygenase in the prostaglandin synthetic pathway in platelets
and vessels by low doses of aspirin. The finding of aspirin
as a prophylactic measure for placental-mediated disease has
huge implications for first-trimester screening for PE, in that
such screening not only identifies a high-risk group that can
be subjected to close monitoring, but an intervention can be
instituted, with a significant reduction in the disease process. As
noted above, a combination of medical and obstetric history,
maternal characteristics, mean arterial pressure, UA PI, PAPPA
and PLGF could identify a high proportion of pregnancies at risk
for severe PE, IUGR and stillbirths, and use of aspirin in this high-
risk group could substantially reduce adverse perinatal outcomes.
The prophylactic use of low-dose aspirin is associated with a
significant decrease of almost 50% in perinatal death associated
with severe early-onset pre-eclampsia, provided the treatment is
initiated before 16 weeks’ gestation
Conclusion
Central to our understanding of the pathogenesis of early-
onset PE is absolute utero-placental ischaemia, on the basis
of lack of placental vascular transformation between eight
and 16 weeks’ gestation. By contrast, relative utero-placental
ischaemia, due to a mismatch between utero-placental blood
flow and increased demand for nutrients, occurring late in
pregnancy, may be central to the development of late-onset PE.
These pathogenic mechanisms have advanced our understanding
of this condition, leading to better prediction, screening and
intervention modalities.
Screening for PE in the first trimesterwill trigger commencement
of a prophylactic therapeutic intervention with low-dose aspirin,
resulting in a substantial reduction in early-onset PE. Screening in
the second trimester will lead to more focused management of the
screen-positive group, while prediction of adverse foetal outcomes
in established PE in the third trimester, using a combination
of cardiac Doppler, multi-vessel Doppler assessment of foetal
circulation, and biomarkers, could lead to a significant reduction
in foetal perinatal morbidity and mortality rates. Hopefully,
advances in our understanding of this enigmatic disease will lead
to further prophylactic and new therapeutic interventions.
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