Objective: Our objective was to establish reference values for ductus venosus flow velocities during ventricular systole (S wave) and diastole (D wave), the lowest forward velocity during atrial contraction (A wave) and different calculated indices [(S-A)/D), (S-A)/Vmean, (S-A)/S, S/A, S/D)].
Methods: Ductus venosus flow velocity waveforms were obtained from 329 singleton pregnancies at 10-20 weeks of gestation by pulsed-wave color Doppler. Reference values were constructed by means of a quadratic regression model after logarithmic transformation of original data.
Results: A significant increase in blood flow velocity during atrial contraction [A-wave, (3.5 cm/s to 9.9 cm/s and 12.9 cm/s to 66.3 cm/s respectively, 5-95% centile)], during ventricular systole [S-wave, (19.2 cm/s to 30.1 cm/s and 45.1 cm/s to 84.9 cm/s respectively, 5-95% centile)] and during early ventricular diastole [D-wave, (15.7 cm/s to 26.1 cm/s and 37.9 cm/s to 77.9 cm/s respectively, 5-95% centile)]. The venous indices values decreased with increasing gestational age. In 3 of 329 fetuses (0.91%) a reversed flow during atrial contraction was seen.
Conclusion: Assessment of ductus venosus blood flow velocities during first and second trimester is feasible by means of color Doppler flow. The reference ranges and calculated velocities established in this study may be utilized in studies dealing with the role of ductus venosus blood flow in chromosomal abnormal fetuses, fetuses with congenital heart disease or fetal myocardial insufficiency of hypoxic origin.