Evaluate Middle Cerebral Artery Doppler indices (PI/RI) for fetal surveillance.
Doppler Velocities
cm/s
cm/s
cm/s
Doppler Analysis
Pulsatility Index (PI)1.17
Resistive Index (RI)0.70
S/D Ratio3.33
Velocity Interpretation
Indices quantify the shape of the waveform to assess cerebrovascular resistance and fetal physiology.
About this calculator
Overview
Middle Cerebral Artery (MCA) Doppler is a non-invasive ultrasound technique used in fetal medicine to assess fetal wellbeing. It is particularly useful for detecting fetal anemia, where the blood flow velocity increases, and in the assessment of intrauterine growth restriction (IUGR).
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Pro Tips
Measurements should be taken from the proximal third of the MCA near its origin from the Circle of Willis.
The angle of insonation should be as close to zero degrees as possible for accurate velocity readings.
Avoid excessive compression of the fetal head, as this can artificially alter Doppler waveforms.
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Fun Facts
"The MCA allows for the assessment of 'brain-sparing' effect in fetal hypoxia."
"Increased PSV (> 1.5 MoM for gestational age) is the main screening tool for fetal anemia."
"Decreased Pulsatility Index (PI) can indicate redistribution of blood flow to the brain."
"MoM stands for Multiple of the Median."
Formula: RI = (PSV - EDV) / PSV. PI = (PSV - EDV) / TAMV.
