Intravenous urography is a procedure in which X-ray equipment is used to generate images of the urinary tract. In this type of medical test, a high-contrast dye is used to improve the quality of X-ray images that can be used to diagnose diseases of the kidneys, ureters, bladder and urethra. In men, this test is also used to examine the prostate gland.
Structures of the urinary system tend not to show up well in X-ray images. To counter this problem, an intravenous injection of dye is given to a patient before a urogram. Once the dye is injected, it is gradually absorbed by the kidneys and filters through to the ureters and bladder. As the kidneys and other structures absorb the dye, they become more opaque, producing X-ray images that can be read more easily.
Intravenous urography can be used in the diagnosis of several different diseases of the urinary tract. These include kidney stones, chronic urinary infections and obstructions of the structures of the urinary tract. In the case of kidney stones, for example, the stones can be seen clearly on an X-ray after the use of contrast dye. Similarly, the use of dye provides contrast, which can help pinpoint areas of blockage or inflammation.
To prepare for this procedure, patients might be asked to stop taking certain medications for a day or two beforehand. These include people who take metformin, because the combination of the dye and this diabetes medication can damage the kidneys. In addition, patients are asked to avoid eating before the procedure and might be asked to take laxatives the day before. These measures clear the intestines of food and waste, helping to produce clearer X-ray images.
At the start of the intravenous urography procedure, dye is injected intravenously, usually through the arm or hand. As the dye begins to collect in the urinary tract, an X-ray technician takes X-rays at intervals of five to 10 minutes. Ten to 20 X-rays typically are taken over a period of up to 60 minutes. In some cases, the patient might be asked to empty his or her bladder at the end of the session before having one last X-ray image taken.
There are few serious risks and side effects to undergoing intravenous urography. There might be a small amount of pain when the dye is injected and a feeling of warmth in the injection area. Some people might experience an allergic reaction to the dye, possibly including itching and swelling. Severe allergic reactions are very rare, and because the procedure is carried out in a hospital, treatment for such a reaction is carried out quickly. A woman who is pregnant or suspects she is pregnant should avoid undergoing an intravenous urography, because exposure to X-rays might harm the fetus.