Diagnostic ultrasound ( PDFDrive )

988 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
2. Small nonocclusive thrombi in the profunda femoris vein
may be missed if not carefully assessed. It is important to
remember that DVT may initially be demonstrated in the
profunda femoris vein only.
3. hrombosis of a duplicated FV may be challenging to detect.
It is useful to record the presence of this common anatomic
variant in the report for comparison in a subsequent study,
when only one of several FVs may be thrombosed (Fig. 27.35,
Video 27.18).
4. Proximal iliac vein thrombosis may be diicult to demonstrate
because of overlying bowel gas. Loss of respiratory phasicity
should be recognized as a secondary sign suggesting more
proximal thrombosis or obstructive compression by masses
or luid collections (Fig. 27.36). False-negative examination
results may occur when the Valsalva maneuver is used while
the pelvic veins are evaluated in patients with nonocclusive
thrombus in the iliac veins who have well-developed pelvic
venous collaterals.
FIG. 27.34 Slow Flow in Patent, Compressible Vein Without
Deep Venous Thrombosis (DVT). Accompanying Videos 27.16 and
27.17 show slow low in longitudinal plane, and no DVT with
compression.
FIG. 27.35 Thrombus in One of Paired Femoral Veins. Transverse
image of compressed paired femoral veins shows that one of the veins
does not compress because of deep venous thrombosis (DVT). Arrow
shows position of one femoral vein, which is completely compressed
and thus not seen. See also Video 27.18. A, Supericial femoral artery;
V, thrombus in other (paired) femoral vein.
A
B
FIG. 27.36 (A) Patient with large pelvic mass compressing the left external iliac vein (not shown). Monophasic low in left common femoral
vein (CFV). (B) Normal phasic low in right CFV.