Hemodynamics of ductus venosus in normal fetuses during second and third trimester

Objective To establish reference ranges with gestation for Doppler parameters of fetal ductus venosus(DV).Methods Color Doppler ultrasound was used to examine 138 normal singleton pregnancies at 16-41 weeks gestation.Flow velocity waveforms were recorded from the ductus venosus.Peak velocity during ventricular systole(S-peak),peak velocity during ventricular diastole(D-peak),lowest velocity during atrial contraction(A-wave) and mean velocity(Vmean) were measured at DV inlet and S/A ratio,S/D ratio,(S-A)/S ratio,((S-A)/D) ratio and((S-A)/Vmean) ratio were calculated.Results The blood velocity of DV: S-peak,D-peak,A-wave and Vmean increased with advancing gestational age(P(0.01)).S/A ratio,(S-A)/S ratio,(S-A)/Vmean ratio and(S-A)/D ratio decreased with advancing gestational age(P(0.01) or P(0.05)).S/D ratio showed poor correlation with gestational age(r=(0.1),P(0.05)).Conclusions The normal Doppler flow waveform of the DV in fetuses have characteristic triphasic pattern.The blood flow velocity of DV increased with advancing gestational age,while indices of pulsatility for flow in the ductus venosus decreased with advancing gestational age.S/D ratio remains constant throughout gestation.