Antenatal doppler and cerebroplacental ratio pptx

Doppler effects antenatally

1. CEREBROPLACENTAL RATIO

2. FORMULAE.. PI = (peak systolic velocity – end diastolic velocity) / mean flow velocity RI = ( peak systolic velocity – end diastolic velocity) / peak systolic velocity S/D ratio = Peak systolic velocity – End diastolic velocity CPR = MCA PI / UA PI

3. DOPPLER VELOCIMETRY Doppler velocimetry is used to provide an indirect measure of the placental function and fetal status. Because placental capacitance is low, umbilical artery has forward diastolic flow. UA – high flow, low resistance. END DIASTOLIC FLOW INCREASES AS GESTATIONAL AGE ADVANCES

4. MIDDLE CEREBRAL ARTERY MCA vascular bed resistance is almost same throughout pregnancy. RI = 0.75-0.85 In FGR, blood is preferentially distributed to the vital organs like brain, heart and adrenals at the expense of non vital organs – vasodilatation in the cerebral circulation FGR MCA DOPPLER – end diastolic velocity in cerebral vessels increases and pulsatility decreases, - “brain sparing effect”

5. In FGR.. IUGR / FGR / Hypoxia = Upto 70% blood flow shunted through coronaries MCA diastolic flow increases – S/D ratio decreases Placental resistance increases, so UA S/D ratio increases UA SD Ratio >> MCA SD Ratio = “brain sparing effect”

6. CEREBROPLACENTAL RATIO It is a diagnostic index CPR = MCA PI / UA PI Normally, MCA PI / UA PI >1 Cerebral redistribution – MCA PI decreases and UA PI increases So, CPR < 1 – indicative of fetal hypoxia

7. Abnormal : <5 th centile It predicts perinatal outcome in early and late FGR. Predictive value decreases over time Sensitivity is higher in cases with IUGR measured < 34 weeks.

8. EVIDENCE PORTO STUDY – 1100 singleton pregnancies with IUGR Doppler measurements including CPR OUTCOME – adverse perinatal outcome which was a composite of IVH, PVL, HIE, NEC, BPD, sepsis and death Secondary analysis was done to describe the role of CPR in prediction of adverse perinatal outcome.

9. RESULTS.. 881 cases – CPR calculations was done Mean gestational age : 33 weeks 146 cases – CPR < 1, of which 27 (18%) – had an adverse perinatal outcome. 735 cases – CPR >1, of which 14 (2%) had adverse perinatal outcome (OR 11.7; p < 0.0001) Death – 3 cases. All 3 cases had abnormal CPR

10. Prediction of abnormal outcomes was comparable when using all definitions of CPR