Citation, DOI, disclosures and article data
Citation:
Weerakkody Y, Hacking C, Luijkx T, et al. Fetal middle cerebral artery pulsatility index. Reference article, Radiopaedia.org (Accessed on 30 Mar 2025) https://doi.org/10.53347/rID-33737
The fetal middle cerebral artery (MCA) pulsatility index (PI) is a key parameter used in fetal middle cerebral arterial Doppler assessment. It is calculated by subtracting the end-diastolic velocity (EDV) from the peak systolic velocity (PSV) and then dividing by the time-averaged (mean) velocity (TAV):
Practical points
The fetal MCA PI normally has a high value. The mean value (normal reference range) slowly decreases through gestation from around 28 weeks onwards. A low PI reflects the redistribution of cardiac output to the brain due to the fetal head sparing theory.
See also
Which of the following is correct regarding a normal antenatal Doppler ultrasound study?
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1. Ebbing C, Rasmussen S, Kiserud T. Middle cerebral artery blood flow velocities and pulsatility index and the cerebroplacental pulsatility ratio: longitudinal reference ranges and terms for serial measurements. Ultrasound Obstet Gynecol. 2007;30 (3): 287-96. doi:10.1002/uog.4088 - Pubmed citation
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2. Komwilaisak R, Saksiriwuttho P, Ratanasiri T et-al. Pulsatility index of the middle cerebral artery in normal fetuses. J Med Assoc Thai. 2011;87 Suppl 3: S34-7. Pubmed citation
Multiple choice questions:
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