Middle cerebral artery peak systolic velocity for the diagnosis of fetal anemia: the untold story.

The use of the middle cerebral artery peak systolic velocity (MCA-PSV) for the diagnosis of fetal anemia has been one of the few discoveries in fetal medicine that is changing the standard of care in the management of affected pregnancies1. This has led to a more than 70% reduction in the number of invasive tests, which often cause fetal death, in the assessment of red-cell alloimmunized pregnancies1. Up to 2 years ago, I thought that only a few doctors in the world were relying upon the MCA-PSV for the diagnosis of fetal anemia. However, in 2003 at the Society for Maternal–Fetal Medicine (SMFM) meeting in San Francisco and a few months later at the American Institute of Ultrasound in Medicine (AIUM) meeting in Montreal, during my lectures on fetal anemia, I asked my colleagues, ‘how many of you are using the middle cerebral artery peak systolic velocity in fetuses at risk of anemia?’, and I was pleasantly surprised to see that about 70% of the participants raised their hands. I then realized that the use of the MCA-PSV in fetal medicine had become a reality.