What is the significance of MCA-PSV >1.5 MoM?

MCA-PSV >1.5 times the median for gestational age is the threshold for suspected fetal anemia (hemoglobin <2 SD below mean for GA). Sensitivity for moderate-severe anemia is 88% with 12% false-positive rate (Mari 2000).

What is the cerebroplacental ratio?

CPR = MCA-PI divided by UA-PI. CPR <1.0 (or below 5th percentile for GA) indicates cerebrovascular redistribution (‘brain sparing’), predicting adverse perinatal outcome especially in late-onset FGR and post-term pregnancies.

In which conditions is MCA PSV most useful?

Rh and Kell isoimmunization, parvovirus B19 fetal infection, twin-twin transfusion syndrome (TAPS), and other fetal anemias. MCA PSV has largely replaced invasive fetal blood sampling as first-line anemia screening.

Middle Cerebral Artery PSV and CPR Calculator

Calculate MCA peak systolic velocity (PSV) to screen for fetal anemia and cerebroplacental ratio (CPR = MCA-PI/UA-PI). MCA-PSV >1.5 MoM is the threshold for fetal blood sampling. Low CPR predicts adverse perinatal outcome in late FGR.

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