fetal ultrasonography umbilical artery doppler sonography assessment 2025-06-09T08:53:07Z Measurement of characterisitc of the umbilical artery flow such as end-diastolic umbilical artery flow and umbilical artery pulsatility index (PI) by fetal Doppler ultrasound. Elevated PI may indicate increased resistance in placental circulation with the risk of reduced oxygen and nutrient delivery to the fetus.