Ultrasound examination:
Image-directed pulsed and colour Doppler equipment GE Voluson E8 and
E6(General Electric Healthcare ,Europe) ultrasound machine with
transabdominal transducer was used to perform Doppler studies of the
Umbilical artery(UA) ,Middle cerebral artery(MCA),Ductus venosus ( DV)
and aortic isthmus (AoI) .
Doppler indices were calculated from waveforms obtained during minimal
fetal activity and the absence of fetal breathing movement, at an
insonation angles < 300. At least
three Doppler waveforms were taken for each measurement and the most
representative one was included for analysis. The PI was recorded for
the Umbilical artery, Middle cerebral artery and Ductus venosus. The
parameters were plotted against established centiles for gestation using
Barcelona fetal medicine reference charts.
Umbilical artery Doppler and DV Doppler were assessed as PI value
percentile or end-diastolic velocity was classified as absent (AEDF) or
reversed (REDF). Umbilical artery with PI
>95th centile for GA or with AREDF was
considered as abnormal umbilical artery Doppler flow. MCA-PI< 5th centile for gestational age was considered as an
evidence of cerebral redistribution or ‘brain sparing ‘and considered as
abnormal MCA doppler flow . Also ratio of MCA PI and UA PI that is
cerebroplacental ratio (CPR) was calculated. CPR
<2nd percentile for GA was considered as
abnormal .Similarly DV with PI >95thpercentile for GA or with AREDF was considered as abnormal DV doppler
flow.