Pressure and flow in the umbilical cord

Area of Science:

• Fluid Dynamics
• Maternal-Fetal Medicine
• Biomedical Engineering

Background:

• The umbilical cord's structure is crucial for fetal circulation.
• Umbilical coiling index (UCI) is a common but potentially limited metric.
• Understanding blood flow dynamics is vital for fetal health.

Purpose of the Study:

• To investigate fluid dynamics of blood flow in umbilical vessels.
• To assess the impact of umbilical cord geometry on pressure and flow.
• To evaluate the efficacy of UCI in predicting hemodynamic characteristics.

Main Methods:

• Computational fluid dynamics (CFD) modeling of umbilical blood flow.
• Analysis of pressure drop and flow profiles under various geometric conditions.
• Comparison of steady and pulsatile flow characteristics.

Main Results:

• Umbilical coiling index (UCI) is insufficient to differentiate significant variations in pressure and flow.
• Helical geometry, rather than simple coiling, is key for determining steady pressure drop.
• Vessel constrictions drastically increase pressure drop and alter flow profiles.
• Pulsatile flow pressure closely approximates the time-averaged value.
• Peak systolic pressure is consistently lower in non-straight cords.

Conclusions:

• Mean helical geometry can predict steady pressure drop in complex umbilical cords.
• Umbilical cord helicity may dampen extreme arterial pressures, offering an evolutionary advantage.
• Vessel constrictions pose a significant risk by increasing pressure and altering flow.