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The Cerebro-placental Ratio as a Prognostic Factor of Foetal Outcome in Patients with Third Trimester Hypertension.
Parshuram, P.L.; Mwango, G.; Wambugu, M.; Ong'ech, J. & Mwachaka, P.
Abstract
Background: Hypertensive disorders of pregnancy can cause complications in both the
maternal and fetal circulations resulting in poor fetal outcome. These circulations can be
safely and non-invasively assessed using arterial Doppler indices of the umbilical and
middle cerebral arteries to obtain the cerebro-placental ratio. The study objective was to
determine the role of the cerebro-placental ratio as a prognostic factor of fetal outcome in
patients with hypertensive states of pregnancy delivered at least 32 weeks of gestation by
dates.
Methods: This was a prospective cohort study undertaken at Kenyatta National Hospital, a
tertiary referral hospital in Nairobi. A total of 160 gravid patients of median age 28 years
and at least 32 weeks gestations were recruited from labor ward over a 9 month study
period by consecutive sampling method. Doppler ultrasound analyses of the foetal
umbilical and cerebral arteries were done and the cerebro-placental ratio calculated.
Results: At sonography, the average ultrasound age was 31 weeks. The median gestation at
admission was 34 weeks. Twenty nine percent had an abnormal Cerebro-placental ratio
(<1.0).125/160 (78%) delivered via caesarean section and 35/160(22%) delivered
vaginally.51/160 (32%) severe pre-eclamptic toxaemia out of which 39% had cerebroplacental
ratio<1.0 109/160(68%) had mild pre-eclamptic toxaemia out of which 24% had
cerebroplacental ratio <1.0 Still births were 12.5 times more likely in mothers with cerebroplacental
ratio <1.0 than those with CPR ≥ 1.0 (p value ≥ 0.05). A foetal birth score < 7
was 66 times more often in mothers with cerebro-placental ratio< 1.0 than mothers with
CPR≥ 1.0. (P ≥ 0.05). Low birth weight was 4.7 times more likely among mothers with
cerebroplacental ratio < 1.0.as compared to those with mothers with CPR≥1.0 (95% CI 2,
11.1; p≥0.001). A foetal birth score < 7 was 66 times more likely among neonates delivered
vaginally as compared to those born via caesarean section(95% CI 1.3, 23; p=0.02). Still
births were 14.5 times more often than among neonates born vaginally as compared to
those born via caesarean section (95% CI 3, 84; p≥0.001). The prognostic Odds Ratio for
cerebro-placental ratio was 12.5 for live births (95% CI 2, 74; p=0.005), 66 for fetal birth
score <7 (95% Confidence interval 13, 340; p< 0.001) and 4.7 for low birth weight (95% CI
2, 11.1; p< 0.001) and 1.1 (95% CI 0.9, 1.4; p=0.327).
Conclusion: Cerebro-placental ratio is significantly predictive of adverse perinatal
outcome when used to monitor mothers with hypertensive states of pregnancy. Cerebroplacental
ratio.
Keywords
Cerebro-placental Ratio; Prognostic Factor; Foetal Outcome; Third Trimester; Hypertension
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