Umbilical blood flow patterns directly after birth before delayed cord clamping

Area of Science:

• Neonatal Physiology
• Perinatal Medicine
• Obstetrics

Background:

• Delayed umbilical cord clamping (DCC) impacts neonatal cardiopulmonary transition and blood volume.
• Understanding umbilical vessel blood flow during DCC is crucial but limited.
• This study aims to characterize umbilical blood flow patterns and duration during DCC.

Purpose of the Study:

• To describe the duration of umbilical blood flow during delayed cord clamping.
• To analyze the patterns of venous and arterial blood flow in the umbilical cord post-birth.
• To investigate the relationship between umbilical flow and cord pulsations or infant breathing.

Main Methods:

• Doppler ultrasound was used to measure arterial and venous umbilical blood flow.
• Measurements were taken in uncomplicated term vaginal deliveries during DCC.
• Flow patterns and duration were evaluated from birth until cord clamping.

Main Results:

• Umbilical venous flow continued until clamping in 33% of infants, with a median duration of 5:13 min:sec.
• Umbilical arterial flow continued until clamping in 43% of infants, with a median duration of 5:16 min:sec.
• Venous flow patterns varied, becoming continuous and influenced by infant breaths and crying; arterial flow could be pulsatile or continuous.

Conclusions:

• Umbilical venous and arterial flow persist for extended periods during DCC, longer than previously recognized.
• Breathing appears to be a significant factor in net placental transfusion.
• The cessation of umbilical cord pulsations does not correlate with the end of umbilical blood flow.