Kuldeep Singh
The uteroplacental and fetoplacental circulations can be assessed by color Doppler a non-invasive method for understanding and studying fetal circulations. The uterine artery flow tells us the status of the uteroplacental circuit. The umbilical artery, middle cerebral artery, descending aorta, ductus venosus and umbilical vein study tells us the fetal adaptation to any hypoxic insult. With impaired placentation causing changes in the uterine artery one needs to be carefully surveying the fetal circulation for any adaptive changes. With hypoxic insult the blood flows preferentially to vital organs like the brain, heart and adrenals with compensatory shunting from the non-vital organs the abdominal viscera and lower limbs. The three ratio systolic/diastolic ratio, pulsatility index and resistive index are markers of resistance and thus are reflecting impedance values which are inversely proportional to the amount of blood flow in the respective vessel or organ. So brain sparing causes a high PI and brain edema would finally cause a rise in the Middle cerebral artery PI.
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