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Updated: Aug 2, 2026
14:19
Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction
Published on: June 29, 2013
Changes in umbilical venous velocities with physiologic perturbations
1Department of Obstetrics and Gynecology, Arizona Health Sciences Center, Tucson 85724, USA.
American Journal of Obstetrics and Gynecology
|April 14, 2000
Summary
Umbilical venous Doppler flow velocity changes originate in the fetus and travel towards the placenta. This study tracked these changes in human fetuses to determine transmission direction.
Area of Science:
- Fetal physiology
- Cardiovascular dynamics
- Medical imaging
Background:
- Umbilical cord blood flow is crucial for fetal development.
- Doppler velocimetry is a key tool for assessing fetal well-being.
- The origin and transmission of flow variations in the umbilical system are not fully understood.
Purpose of the Study:
- To determine the direction of transmission of umbilical venous Doppler flow velocity changes.
- To investigate the origin of flow variations within the fetal umbilical circulation.
Main Methods:
- Simultaneous umbilical arterial and venous velocities were recorded using Doppler.
- Measurements were taken at proximal (fetal) and distal (placental) umbilical cord sites.
- Analysis focused on fetuses exhibiting venous pulsations or breathing episodes.
Main Results:
- Venous pulsations occurred earlier in the cardiac cycle at proximal sites compared to distal sites.
- Phase delays in venous velocities were significantly longer at distal sites.
- These timing differences indicate a directional transmission of flow changes.
Conclusions:
- Umbilical venous velocity changes originate in the fetal venous system.
- Flow variations are transmitted from the fetus towards the placenta.
- Findings suggest the fetal circulation is the primary source of these observed Doppler changes.
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