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

Lin et al
Postphlebitic syndrome is a common complication
of pelvic and lower extremity DVT. 11
Inflammation and scarring of venous valves
often lead to valve incompetence and reflux,
resulting in venous congestion, decreased muscle
perfusion, and increased tissue permeability. 12,13
Patients with postphlebitic syndrome have pain,
swelling, heaviness, cramps, and tingling in the
affected limb. 14 The incidence of postphlebitic
syndrome may be equal or possibly increased
compared with calf or thigh DVT. 12,15,16
Monophasic waveforms are reliable indicators
of proximal iliac vein or IVC thrombosis.
Approximately 40% of monophasic waveforms in
this series were secondary to iliac vein thrombosis.
Most (68%) of these iliac vein thromboses
extended from leg veins, and one third were
isolated to the iliac vein. Although the actual
incidence of iliac vein thrombosis in the study
population was not investigated, a future
prospective study may evaluate the incidence of
iliac vein thrombosis in acute DVTs and the percentage
of iliac vein thrombosis that have
monophasic waveforms.
A considerable portion (21%) of the patients with
monophasic waveforms were also found to have
lymph nodes, tumors, and hematomas, which
compressed more proximal veins. These findings
are clinically relevant to patient treatment and
stress the importance of following monophasic
waveforms when initially encountered.
Asymmetry of waveforms, with normal phasic
variation on one side and loss of phasic variation
on the other side, may help localize abnormalities
to the side of the monophasic waveform. Bilateral
monophasic waveforms suggest an IVC thrombus
or a large structure, such as an intrauterine pregnancy,
compressing both iliac veins or the IVC.
The waveforms of both common femoral veins
should be compared with each other in all lower
extremity VD sonograms.
A
Figure 4. A and B, Spectral Doppler waveforms of the left (A) and right
(B) common femoral veins (CFV) in a 71-year-old female patient with
metastatic bladder carcinoma show asymmetry of waveforms, with
monophasicity in the left common femoral vein. C, Follow-up post–intravenous
contrast CT shows large necrotic lymph nodes compressing the
left external iliac vein (arrow).
B
C
J Ultrasound Med 2007; 26:885–891 889