Reference ranges for fetal venous and atrioventricular blood flow parameters

Area of Science:

• Perinatology
• Fetal Physiology
• Medical Imaging

Background:

• Assessing fetal well-being is crucial during pregnancy.
• Doppler ultrasound is a key tool for evaluating fetal circulation.
• Establishing normative data for fetal venous and atrioventricular blood flow is essential for accurate interpretation.

Purpose of the Study:

• To establish gestational age-specific reference ranges for Doppler parameters of fetal venous and atrioventricular blood flow.
• To investigate the relationship between these Doppler parameters and gestational age in normal singleton pregnancies.

Main Methods:

• A cross-sectional study involving 143 normal singleton pregnancies (20-40 weeks' gestation).
• Color flow Doppler and pulsed Doppler were used to record flow velocity waveforms from the ductus venosus, right hepatic vein, and inferior vena cava.
• Measurements included peak velocities, time-averaged maximum velocities, peak velocity index for veins (PVIV), pulsatility index for veins (PIV), and atrioventricular valve E/A ratios.

Main Results:

• Fetal venous blood flow velocities and atrioventricular valve velocities/E/A ratios significantly increased with gestational age.
• Peak velocity index for veins (PVIV) and pulsatility index for veins (PIV) significantly decreased with increasing gestational age.
• Blood flow velocities were highest in the ductus venosus, while PVIV and PIV were highest in the hepatic vein.

Conclusions:

• The study provides reference ranges for fetal venous and atrioventricular Doppler parameters across gestation.
• Decreasing PVIV and PIV with gestation suggest decreasing cardiac afterload and improving diastolic ventricular function.
• These findings contribute to a better understanding of normal fetal cardiovascular development and can aid in identifying potential abnormalities.