Doppler Spectral Wave Patterns of Ductus Venosus: Do They Change with Foetal Position in the First Trimester?

Abstract

Introduction: The ductus venosus is a branch of the umbilical vein that carries oxygenated blood to the foetus’s right atrium. Assessing the ductus venosus during the first trimester is used as one of the soft markers to detect aneuploidy. Since, operators often have to wait for extended periods for the foetus to assume the desired position. Prolonged scanning increases costs and reduces efficiency by extending scan times. Therefore, it is crucial to determine whether the foetal position affects the ductus waveform. In India, where the number of qualified operators is limited compared to the high demand for scans, efficiency is particularly important. Aim: To observe the spectral flow patterns on colour Doppler of the ductus venosus in supine, prone, and oblique positions of the foetus. Materials and Methods: The authors conducted a prospective observational study at Kempegowda Institute of Medical Sciences and Delta Diagnostics, Bengaluru, Karnataka, India, between August 2021 and December 2021. The study included 100 pregnant women who underwent routine first-trimester antenatal scans between 11 weeks and 13 weeks and six days. Colour Doppler flow mapping was used to visualise the umbilical vein, ductus venosus, and foetal heart. Spectral flow patterns of the ductus venosus were obtained in the supine, prone, and oblique positions of the foetus. The parameters studied were peak systolic velocity, end-diastolic velocity, and ductus venosus pulsatility index. Friedman’s Test followed by Wilcoxon Signed Rank Post hoc test was used to compare the mean values of systolic and diastolic velocity and pulsatility index between different foetal positions. Results: A total of 100 singleton pregnancies were included, mean gestational age was 12 weeks and four days. There was no difference in the subjective evaluation of the waveforms obtained in different positions. All foetuses exhibited type 1 spectral waveform. There were no false positives in the subjective evaluation for ‘a’ wave reversal. However, there was a significant difference in the systolic and diastolic velocities of the ductus venosus with different foetal positions, with a p-value of less than 0.001. The mean systolic velocities in supine, prone, and oblique positions were 60.09 cm/s, 51.59 cm/s, and 31.38 cm/s, respectively. The mean diastolic velocities in supine, prone, and oblique positions were 25.23 cm/s, 22.05 cm/s, and 19.05 cm/s, respectively. There was no significant difference in the pulsatility index among the supine, prone, and oblique positions. Conclusion: Radiologists do not need to wait for the foetus to be in the horizontal position to assess the ductus venosus waveforms. The waveforms can be evaluated in other foetal positions without affecting the assessment of aneuploidy risk.