Last updated: 02/17/2009

Phlebography (also called venography, ascending contrast phlebography, or contrast phlebography) is an invasive diagnostic test that provides a constant image of leg veins on a fluoroscope screen. Phlebography identifies the location and extent of...

blood clots, and enables the condition of the deep leg veins to be assessed. It is especially useful when there is a strong suspicion of deep vein thrombosis, after noninvasive tests have failed to identify the disease.

Phlebography is the most accurate test for detecting deep vein thrombosis. It is nearly 100% sensitive and specific in making this diagnosis. (Pulmonary embolism is diagnosed in other ways.) Accuracy is crucial since deep vein thrombosis can lead to pulmonary embolism, a potentially fatal condition.

Phlebography is not used often; however, because it is painful, expensive, time-consuming, exposes the patient to a fairly high dose of radiation, and can cause complications. In about 5% of cases, there are technical problems in conducting the test.

Phlebography takes 30–45 minutes, and can be done in a physician's office, a laboratory, or a hospital. During the procedure, the patient lies on a tilting x ray table. The area where the catheter will be inserted is shaved, if necessary, and cleaned. In some cases, a local anesthetic is injected to numb the skin at the site of the insertion. A small incision may be required to make a point for insertion. The catheter is inserted and the contrast solution (or dye) is slowly injected. Injection of the dye causes a warm, flushing feeling in the leg that may spread through the body. The contrast solution may also cause slight nausea. Approximately 18% of patients experience discomfort from the contrast solution.

In order to fill the deep venous system with dye, a tight band (tourniquet) may be tied around the ankle or below the knee of the side into which the dye is injected, or the lower extremities may be tilted. The patient is asked to keep the leg still. The physician observes the movement of the solution through the vein with a fluoroscope. At the same time, a series of x rays is taken. When the test is finished, fluid is injected to clear the contrast from the veins, the catheter is removed, and a bandage is applied over the injection site.