A renal angiogram is a test used to examine the blood vessels of the kidneys. The test is performed by threading a catheter through the main vessel of the pelvis, up to the renal artery that leads into the kidney. Contrast medium is then injected into the renal artery through the catheter, and images of the vessels of the kidney are taken. The test is a useful aid in evaluating kidney function and diagnosing any narrowing of the arteries, blood clots, tumors or aneurysms.