What Is an Intravenous Pyelogram?

What to expect when undergoing this test

An intravenous pyelogram is a medical imaging test that uses contrast media (also known as dye) injected into the veins to help see the urinary system clearly on an X-ray. An intravenous pyelogram is sometimes abbreviated as "IVP." It is also known as intravenous urography, or an intravenous urogram, and can be abbreviated as "IVU."

what to expect during an intravenous pyelogram
Illustration by Cindy Chung, Verywell 

Purpose of the Test

An intravenous pyelogram is used to see the structures and outlines of the kidneys, ureters, and bladder. With better visibility, doctors can see abnormalities, such as scarring, tumors, or kidney stones

Your doctor might order an intravenous pyelogram as an early test to help diagnose causes of certain signs and symptoms, such as abdominal or flank pain, pain during urination, difficulty urinating, or blood in urine.

An intravenous pyelogram can assist doctors in identifying, among other things:

  • Kidney or bladder stones
  • Tumors or cysts in the kidneys, ureters, or bladder
  • Scarring after urinary surgery or trauma
  • Enlarged prostate gland
  • Congenital kidney defects, such as medullary sponge kidney

In the past, intravenous pyelograms were the most common way for doctors to see kidney stones and other objects in the urinary tract. It has become less commonly used since the development of renal ultrasound and CT technology that can clearly show the urinary tract. CT and renal ultrasound do not require the use of contrast media, which can lead to complications (see below). However, an intravenous pyelogram shows some structures better than renal ultrasound and uses much less radiation than a CT scan.

Risks and Contraindications

Risks associated with an intravenous pyelogram are minor, but there can be complications, and it is almost always because of the contrast media used (X-ray dye). Intravenous pyelography is not the only type of medical test that uses contrast media. Dye is used in many medical tests and most of them use quite a bit more of it than an intravenous pyelogram does.

Modern versions of X-ray dye are very safe. 3.1 percent or fewer of all patients getting contrast media experience some sort of reaction to it. These reactions are usually very minor and are divided into two categories: allergy-like and physiologic. Only one to two out of every 5,000 patients experience severe reactions to contrast media.

Allergy-Like Reactions to Dye

A patient doesn't have to be allergic to contrast media in order to exhibit allergy-like reactions to it. While the reasons aren't completely clear, sometimes dyes will trigger a histamine release just like an allergy. Allergy-like reactions are graded as mild, moderate, or severe:

  • Mild reactions may include localized hives, swelling, or itching at the intravenous site, an itchy and scratchy throat, sneezing, conjunctivitis, and nasal congestion.
  • Moderate reactions may include hives and redness spread out away from the intravenous site, swelling of the face, tightness of the throat, possible wheezing, and little or no difficulty breathing. Patients with moderate reactions maintain stable vital signs.
  • Severe allergy-like reactions mimic anaphylaxis, including shortness of breath, swelling of the face and other areas, and anaphylactic shock, which could include decreased blood pressure. 

To decrease the chances of an allergy-like reaction, your doctor may give you steroids at several intervals starting the night before the test, and an antihistamine such as diphenhydramine about an hour before the intravenous pyelogram begins.

Physiologic Reactions to Dye

In addition to allergy-like reactions to contrast media, there are also potential physiologic side effects. These include:

  • Nausea
  • Headache
  • Flushing
  • Elevated blood pressure
  • Altered taste (sometimes described as a metallic taste in the mouth)

The good news is that physiologic reactions are not life-threatening. The bad news is that there's nothing your doctor can do to prevent them the way they can for allergy-like reactions.

Renal Function and Contrast Media

Another rare risk factor of intravenous contrast media is Contrast Induced Nephrotoxicity (CIN). How CIN happens is not fully understood, but there are certain people who are at increased risk:

  • Patients over 60 years old
  • History of dialysis, kidney transplant, single kidney, renal cancer, or renal surgery
  • History of high blood pressure requiring treatment
  • History of diabetes mellitus
  • History of taking metformin or drugs containing metformin combinations
  • Cardiovascular disease
  • Anemia
  • Multiple myeloma

Patients who are dehydrated or who have received intravenous dye in the last 24 hours are also at an increased risk for CIN. Talk to your doctor before getting an intravenous pyelogram if you have any of the risks above.

Extravasation

If the contrast media leaks out of the vein and gets into the surrounding tissue, it's known as extravasation. It is possible to have a local reaction to the dye in that case. If you feel swelling or pain at the site of the intravenous administration, be sure to tell the medical professional performing the test.

Before the Test

Your doctor will give you specific instructions for the intravenous pyelogram. Usually, you will be asked not to eat or drink after midnight on the evening before your test. You might have to take a laxative the night before your intravenous pyelogram to help clear out your colon. That makes it easier to see your urinary system on the images.

Once your doctor prescribes the test, makes sure to tell them if you are pregnant, have any allergies (especially to iodine), or have ever had a reaction to contrast media (dye). 

Timing

Give yourself six hours for the test. The preparation, including receiving an antihistamine and the contrast medium, will take about an hour. The pyelogram will take anywhere from one to four hours.

Location

An intravenous pyelogram is performed at an imaging center, which might be at a hospital.

What to Wear

You'll most likely be asked to change into a gown, so wear something comfortable and easy to change out of. 

What to Bring

There is a bit of downtime as you are waiting for some parts of the process to take place. Consider bringing something to read.

During the Test

When you arrive for your test, check in at the desk and you'll be sent to change into a gown.

Pre-Test

A nurse will start an intravenous line and probably administer an antihistamine. Typically, you will wait in a room until the medication has had time to circulate.

Throughout the Test

You'll start out by getting some X-rays before the contrast medium is administered. This will be done on an X-ray table. You will probably be asked to change positions a few times. How many times you have to switch positions depends on the reason for the test and what images the doctor is trying to get.

Once the initial images are done, you'll have the dye administered through the intravenous line. The contrast medium could burn a little and some of the reactions mentioned above could happen. Most reactions are nothing to be concerned about. Let the nurse know if you are feeling dizzy, short of breath, or have chest pain.

After the contrast medium has been administered, you'll go back to the X-ray table at regular intervals for additional images. You may have to do this several times and you might be asked to urinate before the final images.

Post-Test

Once the test has been completed, you'll probably be asked by the medical professional to wait a few minutes until the doctor checks to make sure they have all the images they need.

As soon as the test is done, the medical professional will remove the intravenous line and you can change back into your clothes.

After the Test

Depending on risk factors, your doctor might order additional blood tests or exams in the days after an intravenous pyelogram. Be sure to tell the doctor about any difficulty urinating, headaches, or pain after the test.

Results

The images will be interpreted by a radiologist, a physician specially trained in reading X-rays. The radiologist will send the images and the interpretation back to your doctor, who will share them with you. Intravenous pyelogram interpretation is fairly straightforward and your doctor should be able to answer any questions for you.

A Word From Verywell

Getting an intravenous pyelogram is very safe and the use of contrast media is widespread throughout medical diagnostics. This test should help guide your doctor as she tries to diagnose your condition. It is one tool in the toolbox and might not be able to see everything going on in your kidneys. Understand that even if this test doesn't tell you the whole story, it's an important part of getting the right answers.

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