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Fetal middle cerebral arterial peak systolic velocity

Last revised by Dr Jeremy Jones on 20 Sep 2021

The fetal middle cerebral arterial (MCA) peak systolic velocity (PSV) is an important parameter in fetal MCA Doppler assessment.


The fetal MCA should be sampled~2 mm from the origin of the fetal internal carotid artery and the angle of the ultrasound beam and the direction of blood flow should be 0°. Usually, the highest peak systolic velocity (PSV) value is taken.


  • reliable between 18-35 weeks
  • increased PSV can indicate moderate-to-severe anemia in non-hydrops fetuses 4

See also

  • automatic online fetal MCA PSV calculator from www.perinatology.com (c. 2011)

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Cases and figures

  • Case 1: third trimester
    Drag here to reorder.
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