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).
Treatment and prognosis
It is associated with significant perinatal mortality (27-64% 1-3) and overall mortality >50% 1.
- 1. Brar HS, Platt LD. Reverse end-diastolic flow velocity on umbilical artery velocimetry in high-risk pregnancies: an ominous finding with adverse pregnancy outcome. Am. J. Obstet. Gynecol. 1988;159 (3): 559-61. - Pubmed citation
- 2. Ertan AK, He JP, Tanriverdi HA et-al. Comparison of perinatal outcome in fetuses with reverse or absent enddiastolic flow in the umbilical artery and/or fetal descending aorta. J Perinat Med. 2003;31 (4): 307-12. doi:10.1515/JPM.2003.043 - Pubmed citation
- 3. Mandruzzato GP, Bogatti P, Fischer L et-al. The clinical significance of absent or reverse end-diastolic flow in the fetal aorta and umbilical artery. Ultrasound Obstet Gynecol. 1991;1 (3): 192-6. doi:10.1046/j.1469-0705.1991.01030192.x - Pubmed citation
- 4. Merz E, Bahlmann F. Ultrasound in obstetrics and gynecology. Thieme Medical Publishers. (2005) ISBN:1588901475. Read it at Google Books - Find it at Amazon
- 5. Gerber S, Hohlfeld P, Viquerat F et-al. Intrauterine growth restriction and absent or reverse end-diastolic blood flow in umbilical artery (Doppler class II or III): A retrospective study of short- and long-term fetal morbidity and mortality. Eur. J. Obstet. Gynecol. Reprod. Biol. 2006;126 (1): 20-6. doi:10.1016/j.ejogrb.2005.07.008 - Pubmed citation
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