UMBILICAL VEIN WAVEFORM

LESS THAN 8 WEEKS OF GESTATION

• Pulsations always seen.

9-12 WEEKS OF GESTATION

• Pulsations progressively disappear probably due to changes in cardiac filling patterns.

SECOND AND THIRD TRIMESTER

• Continuous forward flow.
• No or very mild pulsations in:
• 20% of waveforms in the free-floating cord.
  33% of waveforms in the umbilical vein.
  78% of waveforms in umbilical sinus or left pulmonary vein.
• During fetal breathing movements.
• Must be distinguished from severe pulsations showing a sharp decrease in blood flow in cases of fetal compromise or non-immune hydrops.

Video clip of intrahepatic umbilical vein waveform

At its origin with the ductus venosus, the waveform changes from continuous to pulsatile with a 3-4 times increase in maximum velocity. It is important to measure during periods of quiet sleep or apnea.