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Chapter 25
Absent End-Diastolic Velocity
in the Umbilical Artery and Its Clinical Significance
Dev Maulik, Reinaldo Figueroa
Among the characteristics of the umbilical arterial
Doppler waveform, the end-diastolic velocity is of
primary hemodynamic and clinical significance. As
discussed in Chap. 10, the end-diastolic velocity demonstrates
an impressive continuous increase throughout
the gestation which is attributable to an ever-increasing
decline of the fetoplacental flow impedance.
It results in a concomitant decrease in the pulsatility
of the waveform and is reflected in the Doppler indices
such as the systolic/diastolic (S/D) ratio and the
resistance index (RI), both of which progressively decline
with the advancing gestation. These changes are
prognostically reassuring. In contrast, any decline in
the end-diastolic velocity with the consequently rising
Doppler indices indicates rising impedance in the fetoplacental
vascular bed and signifies a worsening
prognosis. With the further increase of impedance,
the end-diastolic velocity eventually becomes absent.
Such a development, though rare, is ominous and results
in a profoundly adverse perinatal outcome. An
example of absent end-diastolic velocity (AEDV) is
shown in Fig. 25.1. Occasionally, further hemodynamic
deterioration occurs, resulting in reversal of
the end-diastolic velocity (Fig. 25.2). The impressive
amount of information [1±26] now available on the
clinical significance of the absent and reversed enddiastolic
velocity in the umbilical artery is appraised
in this chapter.
Fig. 25.1. Example of absent end-diastolic velocity in the
umbilical artery. Top: Color Doppler-directed pulsed Doppler
interrogation of the umbilical vessels. Bottom: umbilical
arterial Doppler waveforms. Note that there is no noticeable
loss of low frequency shift information, as the
high-pass filter was set at 50 Hz
Fig. 25.2. Progressive disappearance of the end-diastolic
frequency shift in the umbilical arterial Doppler waveforms
from a pregnancy complicated with severe fetal growth restriction
at 33 weeks' gestation. Top left: Presence of the
end-diastolic frequency shift, although the Doppler indices
were high for the gestational age (systolic/diastolic ratio 5;
resistance index 0.8). Top right: Absence of the end-diastolic
frequency shift. Bottom left: Spontaneous deceleration
with prolongation of the diastolic phase and the appearance
of umbilical venous pulsation. Bottom right: Progression
to the reversal of the end-diastolic frequency shift