What is Obstetric relevance of Doppler values of Cerebroplacental Ratio ?? Q. What is best Doppler study to point out detection of foetal compromise?? Ans: Early detection of abnormal blood flow redistribution patterns is important for efficient fetal Doppler monitoring and is part of meticulous surveillance, with a potential benefit to reduce fetal morbidity and mortality.
Q.2: What is the relevance of CPR(cerebroplacental Ratio?? Ans:-We know that by the term CPR we understand “the ratio between the fetal umbilical artery pulsatility index (UA-PI) and the middle cerebral artery pulsatility index (MCA-PI)”., This ratio is called by sonologists as cerebroplacental ratio (CPR).
Q.3: What does this represent?? What CPR warns us?? Ans:-The CPR(the ratio) represents fetal blood flow redistribution at the early stages of placental insufficiency; Moreover, it has predictive value for adverse intrapartum and neonatal outcomes.
Q 4:-What is the normal curve like in normal pregnancies?? The MCA-PI and CPR values show a similar parabolic curve during the third trimester of pregnancy, with a peak value at 32 and 33 gestational weeks, respectively. The UA-PI showed a linear and gradual decrease over the gestational age.This is the key message that should be in our mind.
The UA-PI, MCA-PI, and CPR reference ranges were reconstructed for each of the vessels for each gestational age between 29 and 41 weeks.
Q.5:-Is it true that: “Fetal adequate blood flow circulation is mainly dependent on normal placental anatomy” ?? Ans: Mostly . But Doppler changes also partly depend on other developmental during pregnancy though an abnormal or malfunctioning placenta can directly affect fetal circulation.
Q.6:-What may go wrong if there is placental bed resistance –which may occasionally cause severe FGR & IUFD ??
Sequence 1:-The umbilical artery (UA) is usually the first fetal blood vessel to be affected by placental insufficiency. The initial increase in placental blood flow, vascular impedance, causes a retrograde increase of blood flow resistance in the UA. decrease in UA-PI represents a process of placental adaptation to the increasing fetal needs for oxygen supply with a steady decrease in blood vessel resistance during the third trimester of pregnancy.
Sequence 2:- Second vascular marker in the cascade of placental insufficiency There is a decreased middle cerebral artery pulsatility index (MCA-PI):-, When placental insufficiency further deteriorates, blood flow resistance in the descending aorta increases, resulting in more blood diverted through the aortic isthmus shunt to reach the fetal brain. This phenomenon is reflected by a decreased middle cerebral artery pulsatility index (MCA-PI), This fall of MCA-PI is an warning sign of second vascular marker in the cascade of placental insufficiency.
However, internationally accepted reference ranges for CPR are lacking.
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