RT Book, Section A1 Figueras, Francesc A1 Gull, Ilan A2 Malinger, Gustavo A2 Monteagudo, Ana A2 Pilu, Gianluigi A2 Paladini, Dario A2 Timor-Tritsch, Ilan E. SR Print(0) ID 1194721632 T1 Fetal Brain Circulation T2 Timor's Ultrasonography of the Prenatal Brain, 4e YR 2023 FD 2023 PB McGraw Hill Education PP New York, NY SN 9781260136166 LK obgyn.mhmedical.com/content.aspx?aid=1194721632 RD 2024/03/28 AB KEY POINTSThe peak systolic velocity (PSV) and the pulsatility index (PI) are the commonly used clinical parameters for the evaluation of fetal cerebral blood perfusion.Ultrasonic measurement of the middle cerebral artery peak systolic velocity (MCA PSV) can predict the existence of moderate-to-severe fetal anemia.Under hypoxic conditions, the fetus redistributes its flow toward the brain, a phenomenon called brain sparing.56 This brain sparing effect is reflected in the MCA flow that shows decreased pulsatility at Doppler evaluation. Decreased pulsatility, which reflects low cerebral resistance to blood flow, constitutes a late manifestation, with acceptable specificity but low sensitivity for clinical applicability.