Lower extremity venographyDefinition: Lower extremity venography is a test used to visualize the veins in the leg. X-rays are a form of electromagnetic radiation like light, but of higher energy, so they can penetrate the body to form an image on film. Structures that are dense (such as bone) will appear white, air will be black, and other structures will be shades of gray. Veins are not normally seen in an x-ray, so a contrast material is injected into the vein to make it visible. In this test, the contrast material is injected into the vein of the affected leg.
Alternative Names: Phlebography; Venogram
How the test is performed: This test is done in a hospital. You will be asked to lie on an x-ray table. Local anesthetic is used, and you may ask for a sedative if you are anxious about the test. A needle is inserted into a vein in the foot of the affected leg so that an intravenous catheter (a short flexible tube) can be inserted. Contrast material is injected into the vein through the catheter. A tourniquet may be placed on your leg so the contrast medium will flow up the deeper veins. X-rays are taken as the contrast material flows through the leg. The catheter is then withdrawn, and the puncture site is bandaged.
How to prepare for the test: You will wear hospital clothing during this procedure. You may be asked to sign a consent form for the procedure. Remove all jewelry from the area being imaged. Inform the health care provider if you are pregnant, if you have allergies to any medication, which medications you are taking (including any herbal preparations), and if you have ever had any allergic reactions to x-ray contrast material or iodine substance.
How the test will feel: The x-ray table is hard and cold, so you may want to ask for a blanket or pillow. You will feel a sharp poke when the intravenous catheter is inserted. As the dye is injected, you may experience a burning sensation. There may be tenderness and bruising at the site of the injection after the test.
Why the test is performed: This test is used to identify and locate thrombi (blood clots) in the veins of the extremity that is affected. Ultrasound is a newer procedure with fewer risks and side effects, and it is used more often than lower extremity venography.
Normal Values: Free flow of the blood through the vein is normal.
What abnormal results mean: Obstructions that are caused by blood clots (deep venous thrombosis), tumors, or inflammation may be found.
What the risks are: - There is a chance of a reaction to the contrast medium.
- There is low radiation exposure; however, most experts feel that the risk of most x-rays is smaller than other risks we take every day. Pregnant women and children are more sensitive to the risks of the x-ray.
- There is a chance of renal (kidney) failure, especially in the elderly or in diabetic patients taking a medication called Glucophage or metformin.
- There is a risk of worsening any clotting that has already occurred in the veins of the leg.
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