RESUMO
OBJECTIVE: To assess peak systolic velocity values in middle cerebral artery (PSMCA) of normal fetuses from 22nd to 38th week of gestation. MATERIAL AND METHODS: We made a prospective study of 33 healthy fetuses from 22nd to 38th to determine peak systolic velocity by Doppler velocimetry. Doppler ultrasound was performed by a single observer, always using the same apparatus. The Doppler tracing was obtained with a sample volume of 1 mm; placement was on the anterior middle cerebral artery, as close as possible to the skullcap. The insonation angle was kept below 20 degrees and the wall filter was adjusted to a frequency of 50-100 Hz. The PSMCA increases from 26.3 cm/s to 57.7 cm/s in middle cerebral artery from 22nd to 38th week of gestation (p < 0.05). There was a significant positive correlation between PSMCA and the gestational values (p < 0.001, r2 = 60.5%). CONCLUSION: In normal fetuses, the PSMCA increases from 22nd to 38th week of gestation. The Doppler velocimetry values for normal fetuses could be compared with those obtained during fetal anemia.