Varicose Veins and Spider Veins Workup

Laboratory tests are not useful for patients with varicose veins.

The goal of imaging studies is to identify and map all areas of acute or chronic obstruction and all areas of reflux within the deep and superficial venous systems. Successful imaging of the deep venous system requires a thorough knowledge of venous anatomy and physiology and a meticulous attention to detail. The most useful modalities available for venous imaging are contrast venography, magnetic resonance imaging (MRI), and color-flow duplex ultrasonography.

Duplex ultrasonography

Duplex ultrasonography is the standard imaging modality for diagnosis of varicose insufficiency syndromes and for treatment planning and preoperative mapping.

Two-dimensional ultrasonography forms an anatomic picture based on the time delay of ultrasonic pulses reflected from deep structures. Structures that absorb, transmit, or scatter ultrasonic waves appear as dark areas; structures that reflect the waves back to the transducer appear as white areas in the image. Vessel walls reflect ultrasound; blood flowing in a vessel absorbs and scatters ultrasound in all directions. The normal vessel appears as a dark-filled white-walled structure.

Duplex ultrasonography is a combination of anatomic imaging by 2-dimensional ultrasound and flow detection by Doppler-shift. With duplex ultrasonography, after the 2-dimensional anatomic image is displayed, a particular spot in the image can be selected for Doppler-shift measurement of flow direction and velocity.

Color-flow imaging (sometimes called triplex ultrasonography) is a special type of 2-dimensional ultrasonography that uses Doppler flow information to colorize areas of the image in which flow has been detected. Vessels in which blood is flowing are colored red for flow in one direction and blue for flow in the other, with a graduated color scale to reflect the speed of the flow. Modern color-flow duplex ultrasonography equipment can provide flow information in conjunction with surprisingly high-resolution views of both deep and superficial venous systems. Structural details that can be observed include the most delicate venous valves, small perforating veins, reticular veins as small as 1 mm in diameter, and (using special 13-MHz probes) even tiny lymphatic channels.

Magnetic resonance venography (MRV)

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

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. ^[6]

An intravenous catheter is placed 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.

Assessment of reflux by direct contrast venography is a difficult procedure that requires passing a catheter from ankle to groin with selective introduction of contrast material into each vein segment.

Nearly 15% of patients undergoing venography for detection of deep venous thrombosis (DVT) develop new thrombosis after contrast venography. The incidence of contrast-induced DVT in patients who undergo venography for diagnosis and mapping of varicose veins is not known.

Color-flow ultrasound imaging has become accepted as the standard for evaluation of venous anatomy and gross physiology. For many patients, color-flow imaging alone may be sufficient. For complex cases, however, physiologic tests of venous function may reveal more information. 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 availability of small, relatively inexpensive Duplex ultrasound imaging has reduced the need for physiologic testing.

Venous refilling time

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.

MVO measurement

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 advantage of MVO testing is that it is a functional test rather than an anatomic one, and it is sensitive to significant intrinsic or extrinsic venous obstruction from any cause at almost any level. It can detect obstructing thrombus in the calf veins, the iliac veins, and the vena cava, where ultrasonography and venography are insensitive. It also detects venous obstruction due to extravascular hematomas, tumors, and other extrinsic disease processes.

The disadvantage of the test is that it is sensitive only for significant venous obstruction and does not detect partially obstructing thrombus. It is not useful for detection of venous insufficiency states. A normal MVO absolutely does not rule out deep vein thrombosis.

MPEF test

The MPEF test is used to detect failure of the calf muscle pump to expel blood from the lower leg.

MPEF results are highly repeatable but require a skilled operator to obtain clean meaningful tracings. The patient is asked to perform 10-20 tiptoes or dorsiflexions at the ankle, and the change in some physical parameter that reflects calf blood volume is recorded as the calf muscle is pumped.

In patients without varicose veins, 10-20 tiptoes or ankle dorsiflexions cause the venous capacitance circuit of the calf to be emptied.

In patients with muscle pump failure, severe proximal obstruction, or severe deep vein insufficiency, tiptoes or ankle dorsiflexions have little or no effect on the amount of blood remaining within the calf.