Reference values of normal fetal ductus venosus Doppler flow measurements at 11-14 weeks of gestation

To establish the reference range of normal fetal ductus venosus pulsatility index (DV PI) and ductus venosus (DV) blood flow velocity at 11-14 weeks of gestation. Fetal ductus venosus Doppler flow was measured in singleton pregnancies attending our hospital for early pregnancy nuchal translucency (NT) screening between June 2021 and May 2022. All fetuses were followed up for pregnancy outcome using the following inclusion criteria: Singleton pregnancy; no maternal underlying diseases such as diabetes, hypertension, rheumatism, or other pregnancy complications; fetal crown-rump length (CRL) of 45 to 84 mm; normal NT screening ultrasound; no absent or reversed ductus venosus a-wave; no fetal structural abnormalities; no chromosomal abnormalities during follow-up; and good pregnancy outcome. DV PI, peak ventricular systolic velocity (S-wave), atrial systolic flow velocity (a-wave) and time-averaged maximum velocity (TAMXV) were recorded. The ductus venosus Doppler parameters of 224 fetuses which met the inclusion criteria were analysed. DV PI P5 and P95 ranged from 1.0007 and 1.3415 for a CRL of 45 mm to 0.9734 and 1.2115 for a CRL of 84 mm, indicating a statistically significant correlation with CRL. DV S-wave, a-wave, and TAMXV all increased as CRL increased, demonstrating a statistically significant correlation with CRL values. A reference range of normal fetal ductus venosus Doppler spectral parameters at 11-14 weeks was established to provide a basis for further research into the clinical value of normal and abnormal DV PI values in relation to adverse pregnancy outcomes.