Normal value of PSV in fetal middle cerebral artery

The study found that in the case of fetal intrauterine hemolysis and anemia, the peak water volume (PSV) of the middle cerebral artery will also increase significantly. It has a sensitive predictive value for intrauterine hemolysis caused by thalassemia, Rh intrauterine hemolysis, and microbial infection B19. Generally, a PSV exceeding 1.5MOM (median value) is used as the diagnosis basis, which provides a basis for clinical pre-delivery intrauterine interventional surgery. So how much is the standard PSV of the middle cerebral artery of a fetus worth?

Generally, before 24 weeks of pregnancy, S/D is about 3.5~5.5, not exceeding 5.5; from 24 to 30 weeks, S/D=2.5~5.0, not exceeding 5; from 30 to 36 weeks, S/D=2.5~4, generally not exceeding 4; from 36 to 40 weeks, S/D=1.7~3, generally not exceeding 3. If the fetal middle cerebral artery blood friction resistance index value is high, generally does not affect the fetal brain growth and development, but regular observation is required. Generally, the Doppler blood test of the fetal middle cerebral artery is a sensitive indicator for poor pregnancy outcomes.

The maximum blood velocity in the fetal middle cerebral artery is inversely proportional to the level of fetal anemia, and a PSV of more than 1.5 MOM in the middle cerebral artery is considered to be anemic. The mechanism may be: when the fetus is hypotensive, the fetal preload increases and the blood flow rate in the brain increases; when the fetus is hypertensive, the hematocrit decreases, the blood viscosity decreases, and the blood flow rate in the whole body increases.

Analyzing the data, our experience shows that the maximum water flow in the fetal middle cerebral artery cannot exceed 1.5 MOM, and this 1.5 MOM is more than the number of weeks of pregnancy x 2. For example, at 24 weeks, 1.5MOM is 24x2=48cm/s.