Blood flow velocity waveforms of the fetal pulmonary artery and the ductusarteriosus: reference ranges from 13 weeks to term

Objective To establish reference ranges for blood flow velocity waveforms o f the fetal main pulmonary artery and the ductus arteriosus during the seco nd and third trimesters of pregnancy. Methods A prospective cross-sectional echocardiographic study was performed in 222 normal fetuses from 13 to 41 weeks of gestation using high resoluti on/color Doppler ultrasound equipment. Results Gestational age-specific reference ranges are given for peak veloci ty across the pulmonary valve, velocities in the ductus arteriosus, peak sy stolic velocity in the ductus arteriosus-to-peak velocity across the pulmon ary valve ratio, ductal systolic velocity-to-diastolic velocity ratio, duct al resistance index and ductal pulsatility index. In the ductus arteriosus, increasing fetal heart rate was significantly associated with increasing e nd-diastolic velocity and decreasing systolic-to-diastolic ratio, decreasin g resistance index, and decreasing pulsatility index. Conclusions Based on a prospective study in more than 200 normal fetuses, t he data provide gestational age specific reference ranges for blood flow ve locity waveforms of the fetal pulmonary artery and the ductus arteriosus. T he reference ranges may be helpful in prenatal diagnosis of cardiac malform ations and ductal obstruction from 13 to 41 weeks of gestation.