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Reversal of umbilical arterial end diastolic flow

Reversal of umbilical artery end-diastolic flow (REDF) or velocity is often an ominous finding if detected after 16 weeks. It is classified as Class III in severity in abnormal umbilical arterial Dopplers 6.

The estimated incidence is at ~0.5% of all pregnancies with a much higher rate in intrauterine growth-restricted (IUGR) fetuses.

The feature is seen as a result of a significant increase in resistance to blood flow within the placenta and often represents a "tip of the iceberg" where there is a much larger underlying pathology.

In a normal situation, umbilical arterial flow should always be in the forward direction in both systole and diastole. 

However, during the first 16 weeks, a reversal in end diastolic flow can be a normal finding due to the low resistance arcuate arteries and intervillous spaces not yet being formed.

Flow reversal can also be detected in the fetal aorta.

Ideally, a low wall filter setting (<100 Mhz) and an acute insonation angle of <30% is recommended 4.

The severity can be quantified by the ratio of the maximum antegrade velocity (a) versus the maximum retrograde velocity (b).

It is associated with significant perinatal mortality (27-64% 1-3) and overall mortality >50% 1.

Ultrasound - obstetric
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Article information

rID: 13660
System: Obstetrics
Section: Approach
Tag: cases, cases
Synonyms or Alternate Spellings:
  • Reversal of end diastolic flow (REDF) in umbilical artery
  • Reversed end diastolic flow in umbilical artery
  • Reversed umbilical arterial end diastolic flow
  • Reversal of end diastolic velocity (REDV)
  • Reversal of end diastolic velocity in umbilical artery
  • Reversed umbilical arterial end diastolic velocity
  • Umbilical artery end diastolic velocity reversal
  • Umbilical artery end diastolic flow reversal

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Cases and figures

  • Case 1: intrauterine growth restriction - symmetrical
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