Diagnostic ultrasound ( PDFDrive )

CHAPTER 27 Peripheral Vessels 989
5. Occasionally only the actual coapting of the vein walls is seen
during compression, the so-called vessel “wink.” he FV can
sometimes be diicult to visualize throughout its entire extent.
However, isolated FV thrombus is relatively uncommon,
reported to occur in fewer than 1% to 4% of patients. 83
Complete Venous Doppler Versus More
Limited Examinations
Complete compression venous Doppler from the inguinal area to
the popliteal area is accurate, with less than 1% venous thromboembolic
disease at 3-month follow-up in recent analyses. 88,89
Limited, less detailed examinations have recently been proposed.
A variety of specialties are performing this type of examination
in oice settings, intensive care units, and emergency departments.
he two-point ultrasonography examination of the CFV
and the PV using the compression technique has shown that
most, but not all, proximal DVTs are detected. 90,91 However, this
approach requires a serial examination 1 week later to detect
propagation of calf thrombus into proximal DVT. Two negative
study results, 1 week apart, have shown a low likelihood
of DVT in the months following the tests. 89 he two-point
technique has a 2% to 5.7% chance of detecting DVT on a repeat
examination at 2 weeks. 89,90 A carefully performed complete
thigh venous ultrasound as detailed earlier remains the standard
of care.
Recommendations for Deep Venous
Thrombosis Follow-Up
If the patient’s clinical condition worsens, follow-up venous
Doppler is warranted. In patients with documented DVT on
therapy, a repeat venous Doppler during treatment is rarely
warranted. Repeat Doppler should not be requested unless there
is a clinical change. 85,92 DVT typically lyses or ibroses over 6 to
18 months. Reevaluation near the anticipated end of anticoagulation
should be encouraged to establish a new baseline for patients
who return with new symptoms suggesting recurrent thrombus,
especially those at high risk for recurrent DVT. 85
In patients with isolated calf DVT, a follow-up Doppler
examination at 1 week is warranted if the patient is not treated.
In patients with scarring, pregnant women, patients with technically
limited examinations, or patients with calf pain wherein
DVT is not identiied, it may be prudent to suggest follow-up
in 1 week. It has been established that use of two limited examinations,
1 week apart, is a safe strategy. 90 In an otherwise normal
report, it may be prudent, as a helpful reminder, to state, “If
there remains suspicion for DVT or the clinical condition worsens,
a follow-up should be considered.” 85
Venous Insuficiency
he cause of deep venous insuiciency in many patients is venous
valvular damage ater DVT, which occurs in about 50% of patients
with acute DVT. 93 he physiology of venous insuiciency entails
direct transmission of the hydrostatic pressure of the standing
column of luid in the venous system to the caudal lower extremity.
Clinical manifestations include lower extremity swelling, chronic
skin and pigmentation changes, woody induration, and eventually
nonhealing venous stasis ulcers.
Supericial venous insuiciency has a much better prognosis
than deep venous insuiciency and is associated with extensive
varicosities. Perforating veins communicate between the supericial
and deep system and may also become incompetent owing to
chronic deep venous insuiciency.
For assessment of venous insuiciency, the patient is placed
in an upright or semi-upright position, with the body’s weight
supported by the contralateral lower extremity. his positioning
produces the hydrostatic pressure needed to reproduce venous
insuiciency. Spectral analysis is obtained at several levels of the
deep and supericial venous system during Valsalva and other
provocative maneuvers in the CFV, proximal aspect of the
GSV, PV, and saphenopopliteal junction. Distal augmentation
is more reproducible and easier when performed by a single
examiner. 94
Normal veins ater brisk distal augmentation will show
antegrade low, with a very short period of low reversal as
returning blood closes the irst competent venous valve (Fig.
27.37, Video 27.19). Distal augmentation can be performed
manually and more reproducibly with automated devices that
inlate every 5 to 10 seconds. Insuicient veins show greater
degree of reversed low for a longer duration (Fig. 27.38). It is
important that each vascular laboratory validate its protocol and
quantiication schemes.
Venous Mapping
Vein mapping of supericial leg or arm veins is performed to
determine patency, size, condition, and course of supericial veins
to be used for vein grats. Ultrasound mapping is also helpful
when a vein is harvested as autologous grat material for a
peripheral arterial bypass grat. Any supericial vein can be used,
but the GSV is most oten suitable for grat purposes. he
examination is performed with the patient in the supine or reverse
Trendelenburg position. he GSV is identiied from the level of
FIG. 27.37 Normal Femoral Vein Valve. Accompanying Video 27.19
shows normal coapting of valve, which prevents retrograde low.