DIAGNOSTIC TESTING FOR VARICOSE VEINS
A physical examination is useful in showing the extent of the varicose veins, but it is not always clear from where varicosities arise. This is especially true when varicose veins have recurred after a previous operation. Even experienced vascular surgeons find it difficult to decide exactly where the problem lies without the use of special investigations.
Laboratory tests are usually not useful for patients with varicose veins. The goal of diagnostic testing is to assess the physiological venous function and to visualize and identify all areas of acute or chronic obstruction and all areas of reflux within the deep and superficial venous systems.
The most useful modalities available for venous imaging are contrast venography, magnetic resonance imaging (MRI), and color-flow duplex ultrasonography. 
Venous duplex ultrasound is a non-invasive, pain free way to assess the condition of both your deep and superficial veins. Utilizing ultrasound, the technician and surgeon are able to visualize blood flow and the effectiveness of the valves in the veins to prevent blood from flowing down toward the feet ("venous reflux" or "incompetent valves"). This study is performed in the clinic and typically takes 30 minutes.
Magnetic resonance venography (MRV) is the most sensitive and most specific
test for deep and superficial venous disease in the lower legs and in the pelvis, where other modalities cannot reach. MRV is particularly useful because unsuspected nonvascular causes for leg pain and edema may often be observed on the MRV scan when the clinical presentation erroneously suggests venous insufficiency or venous obstruction.
Direct contrast venography is the most labor-intensive and invasive imaging
technique. In most centers it has been replaced by duplex ultrasonography for routine evaluation of venous disease, but the technique remains extremely useful for difficult or confusing cases like in post-thrombotic Syndrome (PTS). An intravenous catheter is introduced in a dorsal vein of the foot, and radiographic contrast material is infused into the vein. If deep vein imaging is desired, a superficial tourniquet is placed around the leg to occlude the superficial veins and force contrast into the deep veins more quickly.
Physiologic tests of venous function are important adjuncts to anatomic imaging
of venous disease.
Photoplethysmography and strain gauge plethysmography, blood flow measuring techniques, are also used to measure the function of the veins in the leg. Using these tests doctors can find out whether the overall function of all veins in the leg is normal, or if there is a problem with the deep veins, or obstruction in any major vein.
All of these tests are called "non-invasive", that is none of them involves any needles
or injections and, in fact, none of these tests is painful! The physiologic parameters most often measured are the venous refilling time (VRT), the maximum venous outflow (MVO), and the calf muscle pump ejection fraction (MPEF). The venous refilling time
is the time necessary for the lower leg to become suffused with blood after the calf muscle pump has emptied the lower leg as thoroughly as possible.
When perfectly healthy patients are in a sitting position, venous refilling of the lower leg occurs only through arterial inflow and requires at least 2 minutes.
In patients with mild and asymptomatic venous insufficiency, some venous refilling occurs by means of reflux across leaky valves. These asymptomatic patients have a VRT that is 40-120 seconds.
In patients with significant venous insufficiency, venous refilling occurs through high-volume reflux and is fairly rapid. These patients have an abnormally fast VRT of 20-40 seconds, reflecting retrograde venous flow through failed valves in superficial and/or perforating veins. This degree of reflux may or may not be associated with the typical symptoms of venous insufficiency. Such patients often report nocturnal leg cramps, restless legs, leg soreness, burning leg pain, and premature leg fatigue.
A venous refilling time of less than 20 seconds is markedly abnormal and is due to high volumes of retrograde venous flow. High-volume reflux may occur via the superficial veins, the large perforators, or the deep veins. This degree of reflux is nearly always symptomatic. If the refilling time is shorter than 10 seconds, venous ulcerations are so common as to be considered virtually inevitable.
The MVO measurement is used to detect obstruction to venous outflow from the lower leg, regardless of cause. It is a measure of the speed with which blood can flow out of a maximally congested lower leg when an occluding thigh tourniquet is suddenly removed.
The MPEF test is used to detect failure of the calf muscle pump to expel blood from the lower leg.
More information on functional testing for venous disease |
