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Renal venogramDefinition A renal venogram is a way to visualize the veins of the kidney using contrast material and x-rays. 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 renal vein. See also renal arteriography. How the test is performed This test is done in a hospital. You will 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 groin so that an intravenous catheter (a long flexible tube) can be inserted. The catheter is then threaded through the veins until it reaches the renal (kidney) vein. This procedure is monitored by fluoroscopy, a type of x-ray that projects images on a TV monitor. Contrast material is injected, and x-ray images are taken. The catheter is then withdrawn, and the puncture site is bandaged. How to prepare for the test Food and fluids will be restricted 8 hours before the test. Some medications, such as aspirin or other blood thinners, may be stopped before the examination. Do not discontinue any medications unless you are advised to do so by your health care provider. You will wear hospital clothing during this procedure. You will 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 substances. Also, inform the health care provider if you have ever had any bleeding problems. How the test will feel The x-ray table is hard and cold -- you may ask for a blanket or pillow. There is a sting when the anesthetic is given. You may feel some pressure and discomfort as the catheter is positioned. 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 The test will detect thrombosis (presence of a blood clot or clots that partially or completely blocks the vessel), tumors, and venous abnormalities. The test may also be used to measure hormone levels produced by the kidney. This test is now performed only on rare occasions and has largely been replaced by CT scan and MRI. Normal Values A normal renal vein should have no clot or tumor. The contrast should flow quickly through the vein. What abnormal results mean The renal venogram may indicate a blood clot that partially or completely blocks the vessel, a kidney tumor, or an abnormality in the veins. See renal vein thrombosis. What the risks are There is a chance of a reaction to the contrast medium. There is low-level 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. Because veins are accessed in this test, there are also risks of vascular injury, clot formation, and bleeding. Illustrations
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