The reference ranges for fetal ductus venosus flow velocities and calculated waveform indices and their predictive values for right heart diseases.

Objectives: This study endeavors to establish comprehensive normal reference ranges and Z score formulas for ductus venosus (DV) flow velocity parameters and calculated waveform indices across different gestational ages in low-risk fetuses. Furthermore, we aim to validate the predictive capabilities of these Z score calculation formulas in fetuses with diverse right heart diseases.

Methods: A total of 8,953 singleton low-risk fetuses and 70 fetuses diagnosed with different types of right heart diseases were retrospectively enrolled. The DV blood flow velocities during the cardiac cycle (ventricular systolic wave velocity [S], ventricular diastolic wave velocity [D], atrial contraction wave velocity [A], and time-averaged maximum velocity [Tamx]) and calculated waveform indices (preload index [PLI], peak velocity index [PVI], pulsatility index [PI], S/A, and S/D) were obtained. Ninety low-risk fetuses were randomly selected as the control group to verify the predictive value of the Z score model for fetuses with different types of right heart diseases.

Results: As gestational age increased (16-39 weeks), the mean values of S, D, A, and Tamx progressively increased; conversely, the mean values of PLI, PVI, PI, and S/A decreased, respectively, and the median value of S/D remained stable. The Z score-transformed A, PLI, PVI, PI, and S/A could serve as predictors of overall right heart diseases. Different DV Doppler parameter Z scores exhibited varying predictive values for different subtypes of right heart diseases.

Conclusions: Normal reference ranges and corresponding Z score calculation formulas for DV hemodynamic parameters were established, which have demonstrated significant diagnostic values in identifying right heart diseases.