Reference values of ductus venosus flow velocities and calculated waveformindices

In recent years. investigations of the venous vascular system have become i ncreasingly important in the assessment of fetal myocardial function. The a im of the present Doppler ultrasound study was to establish both new refere nce ranges for blood flow velocity during the different phases of the cardi ac cycle (S, SD, D, a) and various calculated indices (S - a)/S, (S - a)V-m ean, (S - a)D, S/D, a/S, S/a) for the ductus venosus. Pulsed-wave colour Do ppler was used in this prospective cross-sectional study to examine 696 wom en with low-risk pregnancies during the period from 14 to 41 weeks' gestati on. Reference curves were constructed for the individual measuring paramete rs based on a growth function from a four-parameter class of monotonic cont inuous functions according to the smallest square principle. A significant increase in blood flow velocity from 48 cm/s to 65.8 cm/s was observed duri ng ventricular systole (= S) from 14 to 41 week's gestation. Similarly, inc reases in blood flow velocity were recorded during the endsystolic phase (= SD) (35.5 cm/s to 50.7 cm/s during early ventricular diastole (= D ) (41.7 cm/s to 58 cm/s, p = 0.0001) and atrial contraction (= a) (11.2 cm/s to 35 cm/s, p = 0.0001), as well as for intensity-weighted mean velocity (30 cm/ s to 48.3 cm/s). The venous indices were associated with significant decrea ses in the individual parameters with increasing gestational age: (S-a)/S f rom 0.77 to 0.47, (S-a)V-mean from 1.21 to 0.67, (S-a)/D from 0.89 to 0.53, S/a from 4.5 to 1.99. A significant increase from 0.23 to 0.53 was observe d only for the quotient a/S. There were no changes in the S/D quotient (fro m 1.15 to 1.13). Regarding intra-observer reliability, more favourable resu lts wen obtained for calculated indices than for measurements of absolute b lood flow velocities. At constant measuring conditions, the reference range s established by this study for blood flow velocities and calculated indice s in the ductus venosus may serve as the basis for Doppler ultrasound follo w-up in a normal patient population as well as for the diagnosis of fetal m yocardial insufficiency of hypoxic and congestive origin. Copyright (C) 200 0 John Wiley & Sons, Ltd.