Assess fetal anemia risk using MCA peak systolic velocity MoM.
Middle cerebral artery peak systolic velocity (MCA-PSV) is the non-invasive gold standard for detecting fetal anemia. Values are converted to multiples of the median (MoM) for gestational age. MoM ≥ 1.5 indicates moderate-to-severe anemia (sensitivity ~100%) and typically triggers cordocentesis or intrauterine transfusion.