The Importance of Monophasic Doppler Waveforms in the Common ...

Monophasic Doppler Waveform in the Common Femoral Vein
This study was limited by its retrospective
design and the substantial number of monophasic
waveforms that remained unexplained
(36%). Technical factors and the presence of
ascites and cardiac conditions were not
explored. For example, monophasic waveforms
in pregnancy may be position dependent; shifting
the patient to the contralateral decubitus
position has been observed, at our center, to
elicit respirophasic variation in a vein that initially
had a monophasic waveform.
External iliac veins are not imaged during routine
evaluation of lower extremity veins. In addition,
the evaluation of iliac veins has not been
addressed by the American College of Radiology
or the American Institute of Ultrasound in
Medicine. In our study, 23 (49%) of the 47 iliac
vein DVTs were initially discovered by VD sonography.
Routine sonographic evaluation of external
iliac veins should therefore be performed
when monophasic waveforms are present. If the
sonographic evaluation is inconclusive, we recommend
further evaluation with CT or MR
venography.
In conclusion, monophasic waveforms in the
common femoral veins are reliable indicators
of proximal venous obstruction, particularly
iliac vein thrombosis. Iliac vein thrombosis is
clinically important because it has an equal
incidence of PE and postphlebitic syndrome
A
Figure 5. Images from a 37-year-old female patient with a history of a
DVT in the left common iliac vein during a remote pregnancy. A and B,
Spectral Doppler waveforms of the common femoral veins show asymmetry
of waveforms, with a monophasic waveform in the left common
femoral vein (FVS; A) and normal phasic variation in the right common
femoral vein (CFV; B). C, Follow-up post–intravenous contrast CT shows
a stenotic segment (arrow) of the left common iliac vein secondary to a
sequela of the prior DVT. LA indicates left common iliac artery; RA, right
common iliac artery; and RV, right common iliac vein.
B
C
890 J Ultrasound Med 2007; 26:885–891