Fetal middle cerebral artery

Among the hemodynamic indices of the fetal middle cerebral artery, PI and RI are the most studied, and they have a good positive correlation with vascular resistance. The RI of the middle cerebral artery has a dual change, that is, the frictional resistance decreases during the compensation period of hypoxia, and the frictional resistance increases during the decompensation period of hypoxia. In this way, the RI value is more difficult to define. The PI value can not only reflect the maximum water flow during contraction, but also the average water flow of the entire cycle. It can also represent the overall state of blood waveform and reflect the hemodynamic changes of the entire cardiac cycle. The PI value is known as the best indicator for predicting fetal hypoxia in the late stage. So what is the reason why the fetus’s middle cerebral artery is higher?

Under normal circumstances, a fetal heart rate of 110-160 is normal. When the baby moves, the acceleration may exceed 160. B-ultrasound shows that the fetus's cerebral artery blood is high, which cannot indicate anything. You need to look at the S/D value. If it is high, it means the fetus is suffering from intrauterine hypoxia. Regular prenatal checkups can be followed up with fetal heart rate monitoring.

How to accurately measure the frequency band of the fetus's middle cerebral artery

1. Obtain a cross-section of the brain axis including the midbrain and greater wing of the sphenoid bone and enlarge the image.

2. Use color Doppler blood imaging to display the Willis aortic circle and the proximal middle cerebral artery.

3. Place the single pulse Doppler sampling frame in the proximal 1/3 of the middle cerebral artery close to the origin of the internal carotid artery (the farther away from the origin of the internal carotid artery, the lower the systolic blood velocity).

4. The intersection angle between the ultrasonic beam and the blood should be as close to 0 degrees as possible.

5. When measuring, be careful to avoid any unnecessary pressure on the fetus' head.

6. During the measurement process, 3 to 10 continuous waveforms should be recorded, with the highest point of the band being PSV (cm/s).

7. PSV accurate measurement can be carried out by manual or automatic linear method. The ten digits of the standard values ​​measured by the automatic linear method are significantly lower than those measured by manual measurement, but are closer to the median values ​​used in clinical care. PI usually uses automatic linear method for measurement, but manual measurement is also possible.

8. When expressing the results, it is necessary to select an appropriate standard value range. The measurement method for the middle cerebral artery should be the same as that used to establish the standard value range.