Phlebography is an x ray test that provides an image of the leg veins after a contrast dye is injected into a vein in the patient's foot.
Phlebography is primarily performed to diagnose deep vein thrombosis—a condition in which clots form in the veins of the leg. Pulmonary embolism can occur when those clots break off and travel to the lungs and pulmonary artery. Phlebography can also be used to evaluate congenital vein problems, assess the function of the deep leg vein valves, and identify a vein for arterial bypass grafting. Ultrasound has replaced phlebography in many cases; but phlebography is the "gold standard," or the best test by which others are judged, even though it is not used routinely.
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.
Fasting or drinking only clear liquids is necessary for four hours before the test, although the procedure may be done in an emergency even if the patient has eaten. The contrast solution contains iodine, to which some people are allergic. Patients should tell their physician if they have allergies or hay fever, or if they have had a reaction to a contrast solution.
Patients should drink large amounts of fluids to flush the remaining contrast solution from their bodies. The area around the incision will be sore for a few days. The physician should be notified if there is swelling, redness, pain, or fever. Pain medication is rarely needed. In most cases, the patient can resume normal activities the next day.
Phlebography can cause complications such as phlebitis, tissue damage, and the formation of deep vein thrombosis in a healthy leg. A rare side effect in up to 8% of cases is a severe allergic reaction to the dye. This usually happens within 30 minutes after injection of the dye, and requires medical attention.
Normal phlebography results show proper blood flow through the leg veins.
Abnormal phlebography results show well-defined filling defects in veins. These findings confirm a diagnosis of deep vein thrombosis:
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Lee A. Shratter, M.D. Lori De Milto Stéphanie Islane Dionne