These arteries are difficult to fully examine on an ordinary X-ray, so a contrast material is injected into one or more arteries so they may be seen and evaluated.
How the test is performed
This test is done in the hospital. You will be asked to lie on the X-ray table. The area where the contrast medium will be introduced is shaved and cleansed. The site is usually in the leg. A local anesthetic is given and a needle is inserted into the artery.
A catheter (a long, narrow, flexible tube) is introduced over a wire into the artery. The catheter is threaded through the main vessels of the pelvis, up to the abdominal aorta (which provides blood from the heart to the lower body). This procedure is monitored by a fluoroscope (a special X-ray that projects the images on a TV monitor).
The contrast medium is then injected into the renal artery through the catheter, and images are taken. The catheter is kept open by flushing it periodically with a saline solution containing heparin (a blood thinner), which will keep the blood in the catheter from clotting.
After the X-rays are taken, the catheter is withdrawn. Pressure is immediately applied to the leg at the site of insertion for 10 to 15 minutes or more to stop the bleeding. After that time, the area is checked and a tight bandage is applied. The leg should be kept straight for an additional 12 hours after the procedure.
Digital Subtraction Angiography (DSI) uses a computer to “subtract” out the bones and tissues in the region so that only the vessels filled with contrast are seen.
How to prepare for the test
Inform the health care provider if you are pregnant and if you have ever had any bleeding problems. Report any allergic reactions you have had to X-ray contrast material or any iodine substance and any other allergic reactions you have had.
You must sign a consent form. Food and fluids will be restricted 8 hours before the test. You will be given a hospital gown to wear and asked to remove all jewelry. You may be given a sedative or pain pill before the procedure.
For infants and children:
The preparation you can provide for this procedure depends on your child’s age and experience. For specific information regarding how you can prepare your child, see the following topics:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- School age test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
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. This does not numb the artery so there will be brief, sharp pain as the catheter is inserted. There is a feeling of pressure as the catheter is advanced.
As the dye is injected, there may be a warm or burning sensation. There may be slight tenderness and bruising at the site of the injection after the test.
Why the test is performed
The test is done to evaluate the blood vessels that feed the kidney. The test may detect stenosis (narrowing of the blood vessel), Blood clots, or aneurysm (a widening of the vein or artery). The test may help evaluate kidney disease or failure, tumors, or kidney function.
It is often used to evaluate donors and recipients before transplantation of a kidney to determine the number of arteries and veins on each kidney.
Some vascular tumors in the kidney can be partially treated by embolizing (placing material in the vessel so it clots and becomes occluded) the feeding arteries.
What abnormal results mean
Renal angiography may show the presence of tumors, narrowing of the artery or aneurysms (widening of the vein or artery), Blood clots, or bleeding in the kidney.
Additional conditions under which the test may be performed:
- acute arterial occlusion of the kidney
- acute renal failure
- atheroembolic renal disease
- renal artery stenosis
- renal cell carcinoma
What the risks are
There is the possibility of significant risk. There is a chance of a reaction to the contrast medium. There is some risk of the catheter damaging the artery or knocking loose a piece of the artery wall, which can then lodge in the vessel and block blood flow. This is rare, however. A clot or bleeding at the puncture site may result in a partial blockage of the flow of blood to the leg.
There is low radiation exposure. However, most experts feel that the risk related most X-rays is smaller than other risks we take every day, such as driving in cars. Pregnant women and children are more sensitive to the risks related to X-rays.
The test should NOT be done if you are pregnant or tend to bleed.
For those with contrast allergies, or other contraindications to contrast use, MRA (Magnetic Resonance Angiography) can be performed. It is non-invasive and can provide similar imaging of the renal vessels.
by Janet G. Derge, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.