Investigation
of venous disease
A
clinical examination carried out with the patient standing will reveal the
extent of any varicose veins and whether they are associated with the long or
short saphenous systems. Further information may be gained by using a tourniquet
test (Brodie, 1846; Trendelenburg, 1890) to determine the source of varices. The
tourniquet is often replaced by the hand of the examiner used to compress the
long or short saphenous vein. The patient lies and the leg is elevated to empty
the veins. The tourniquet is applied high on the thigh and the patient stands
again. The speed at which the varices fill is observed. In the case of varices
from the long saphenous vein these fill within a few seconds without a
tourniquet, but with the trunk of the long saphenous vein compressed in the
thigh much slower filling takes place over 15 or 20 seconds. If filling is not
controlled by an above-knee tourniquet, then a tourniquet is applied to compress
the short saphenous vein, just below the knee. If the varices now fill slowly
then the source of venous reflux is from the SPJ. If the varices continue to
fill rapidly some further source must be the cause. The patient may have
incompetent deep veins or a calf perforating vein. The success of tourniquet
tests lies in the ability of the examiner to assess the varices and their rate
of filling. This may be easy in the case of large varices, but can be vary
difficult with smaller varices. Considerable practice is required for successful
application of these tests (Fig. 16.14).
The
clinical examination should continue by noting the presence and extent of any
skin changes or ulceration at the ankle. An examination of the peripheral pulses
should be carried out. Venous and arterial disease of the lower limb often
coexist, especially in more elderly patients. An abdominal examination completes
the clinical examination in patients presenting with lower limb varices, as
these may occasionally be the result of an abdominal neoplasm causing venous
obstruction.
More
detailed information than can be obtained from clinical examination is useful in
the management of patients with primary varicose veins and essential in the
management of patients with recurrent varices, a history of lower limb venous
thrombosis or venous leg ulcers.
This
method is very useful when examining patients with primary varicose veins,
especially those which are thought to result from SFJ incompetence. The
popliteal fossa contains many veins and if venous reflux is heard it is
difficult to be certain from which veins it arises. However, in patients with
primary varices saphenopopliteal incompetence is usually readily identified. All
surgeons who regularly treat patients with varicose veins should be competent at
this type of investigation. Where the source of recurrent varices or a leg ulcer
is sought, duplex ultrasonography is usually more reliable.
Duplex
ultrasound imaging
This technique involves the use of high-resolution B-mode ultrasound
imaging and Doppler ultrasound to obtain images of veins and simultaneously
measure flow in these vessels. It allows direct visualisation of the veins and
provides functional, as well as anatomical, information. Modern duplex
ultrasound machines represent blood flow as a colour map which is superimposed
on the greyscale image of the vessel. This technique is highly reliable in the
investigation of arteries and veins, and is the most appropriate investigation
to use when detailed analysis of the anatomy and physiology of the venous system
is required.
The
examination is performed with the patient standing. In this position the veins
are filled and easily seen on the ultrasound image. The flow in the veins is
assessed in exactly the same way as when using a hand-held Doppler probe. The
examiner images the vein that he or she wishes to study and compresses the calf
with his/her hand to produce forward flow. This results in upward flow towards
the heart in a normal vein, and is shown as blue in the colour flow map. The
calf is then released to test the competence of the valves. Competent veins show
no flow, but incompetent veins allow reverse flow which is represented as red in
the colour flow map. All lower limb veins may he imaged with ease using modern
ultrasound machines, and therefore the patency and competence of all lower limb
veins may be tested. The examiner steadily works his/her way from the groin to
the ankle testing each major deep and superficial vein along the limb. This
allows a comprehensive map of the
Venography
This investigation is the X-ray equivalent of duplex ultrasonography.
Historically it preceded ultrasonography and has been widely used in the past
for the assessment of patients with vein problems. An ascending venogram is
performed by canulating a vein in the foot in order to inject X-ray contrast
medium. A narrow tourniquet is applied just above the malleoli to direct blood
flow into the deep veins and an injection of nonionic contrast material given to
outline the veins. The technique provides excellent anatomical information but
gives much less information about the veins where the valves have failed. It is
a useful examination for suspected deep vein thrombosis where ultrasonography is
not available.
Incompetent
veins can be shown by descending venography. Here a cannula is inserted in the
femoral vein and contrast material injected with the patient standing. The
contrast material is heavier than blood and flows down the limb though
incompetent valves. Both ascending and descending phlebography is required to
establish as much information as is provided by duplex ultrasonography.
The
source of recurrent varicose veins may be identified by a varicogram. Contrast
material is injected into one of the varicosities and followed to identify its
source. Again, duplex ultrasonography has largely replaced this investigation (Fig.
16.20).