Conventional venography requires an IV or catheter to be inserted into the venous system of interest. The access site must be distal to the vein(s) of concern; for example, to image the entire venous system of the leg, the IV must be inserted into a foot vein. Iodinated contrast, which is much denser than blood, is injected into the IV or catheter. During the injection, the operator utilizes fluoroscopy to visualize and record the flow of contrast through the veins. During the study, the operator can focus on areas of interest, using various techniques to alter flow dynamics, such as the use of tourniquets, varied arm or leg positioning, and additional venipuncture sites. Furthermore, if deemed necessary, the venous access site can be used to perform endovascular interventions if deemed appropriate at that time. Since iodinated contrast can worsen renal function in patients with renal impairment, the renal function should be documented prior to performing this procedure [1]. At our institution, a serum creatinine level above 2.0 mg/dL would be a relative contraindication for conventional venography. Furthermore, there is a significant incidence of allergic reactions to contrast agents, and therefore a careful history should be performed. In cases of minor allergic reaction, such as hives, a corticosteroid premedication regimen is often used.

Conventional venography is considered to be the gold standard for venous imaging, particularly for the diagnosis of DVT and venous stenosis [2, 3]. Validation of all other imaging modalities has historically been based upon comparison to conventional venography. For imaging small veins and branches, the superior spatial resolution of conventional venography renders it superior to all other modalities [4]. Conventional venography can readily diagnose venous thrombosis and venous disease throughout the body. Because conventional venography allows visualization of the flow dynamics of the contrast bolus, collateral venous flow in the setting of venous obstruction is very well demonstrated (Fig. 9.2). This is particularly helpful for determining the hemodynamic significance of a venous stenosis and chronicity of any obstructive pathology. Furthermore, repeat imaging with altered extremity positioning (i.e., provocative maneuvers) can be utilized to recreate symptoms, such as thoracic outlet syndrome. Stenosis, reflux, incompetent valves, and reversal of flow are also well evaluated with conventional venography. Venous mapping for hemodialysis access planning is commonly performed with conventional venography, given the ability to rapidly and easily visualize the configuration of the upper extremity venous system. Another advantage of conventional venography is the ability to perform endovascular therapies at the time of diagnosis. Conventional venography can be tailored specifically for each patient with excellent flexibility for problem solving.

The primary disadvantage of conventional venography is its invasive nature. Because injection of contrast into a vein results in opacification of the associated draining veins in their physiologic direction of flow (typically towards the heart), a vein in the affected extremity must be accessed as distally as possible. In patients with suspected DVT or stenosis, arm or leg swelling is the typical presenting symptom, and thus accessing veins in edematous hands and feet can be extremely challenging. Furthermore, pedal vein access in diabetic patients poses a significant infection risk. In general, there is a 2 % chance of IV or catheter-induced DVT with venipuncture [3]. Iodinated contrast is, by far, the most commonly used contrast agent for conventional venography, although, in rare circumstances, gadolinium or carbon dioxide can be used as the contrast agent. Another disadvantage of conventional venography is that visualization of an opacified vein is highly dependent upon the concentration of contrast. When imaging veins near the IV insertion site, a high concentration of contrast can be easily achieved. However, as the contrast bolus travels centrally into larger veins, progressive contrast dilution occurs, which can limit visualization of the more centrally located vein(s). This problem is markedly worsened in the setting of stenotic or occluded veins, where visualization of the vein(s) central to the lesions can be difficult to impossible when distant from the IV. Furthermore, only the veins in the direct line of flow from the IV access site to the right atrium will be opacified with contrast. This requires multiple access sites if multiple venous distributions are in need of imaging. For example, evaluation of the bilateral pelvic veins requires bilateral lower extremity IVs. A technical disadvantage of conventional venography is inflow artifact, which is the disturbance of the contrast column by non-opacified blood flowing into the opacified vein from a branch vein (Fig. 9.3). This can cause the appearance of a filling defect or stenosis. Careful inspection of a questionable filling defect on sequential frames should demonstrate some degree of subtle fluctuation of the margins of this abnormality in the setting of such inflow artifact. In patients with a mild allergy to iodinated contrast, a corticosteroid premedication regimen should be administered. A history of anaphylactic reaction to iodinated contrast is often considered an absolute contraindication. Adequate renal function is necessary, unless the patient has end-stage renal disease [1]. Conventional venography uses ionizing radiation to generate the images, and the dose can vary widely based on the indication.

In summary, while conventional venography is considered the gold standard imaging modality for venous imaging, it is not typically utilized as first-line imaging for evaluating venous pathology. Conventional venography is often used in cases where endovascular therapy is anticipated, such as acute venous thrombosis (for thrombolysis) or venous stenosis requiring angioplasty or stenting. If other modalities have failed to diagnose an underlying venous process with certainty, then conventional venography can be used to obtain a definitive diagnosis. Some centers still utilize conventional venography as first-line imaging for upper extremity venous mapping for surgical hemodialysis access planning. If the patient has tenuous renal function or anaphylaxis to iodinated contrast, then special measures or alternative imaging modalities should be considered.