Tests and Procedures
Computerized tomography (CT) urogram

Updated: 6/11/2015

Definition

A computerized tomography (CT) urogram is an imaging exam used to evaluate your urinary tract, including your kidneys, your bladder and the tubes (ureters) that carry urine from your kidneys to your bladder.

CT urography uses X-rays to generate multiple images of a slice of the area in your body being studied, including bones, soft tissues and blood vessels. These images are then sent to a computer and quickly reconstructed into very detailed, 2-D images.

During a CT urogram, an X-ray dye (iodine contrast solution) is injected into a vein in your hand or arm. The dye flows into your kidneys, ureters and bladder, outlining each of these structures. X-ray pictures are taken at specific times during the exam, so your doctor can clearly see your urinary tract and assess how well it's working or look for any abnormalities.

Why it's done

A CT urogram is used to examine your kidneys, ureters and bladder. It lets your doctor see the size and shape of these structures to determine if they're working properly and to look for any signs of disease that may affect your urinary system.

Your doctor may recommend a CT urogram if you're experiencing signs and symptoms — such as pain in your side or back or blood in your urine (hematuria) — that may be related to a urinary tract disorder.

A CT urogram may be used to help diagnose conditions that affect the urinary tract, such as:

  • Kidney stones
  • Bladder stones
  • Infection
  • Tumors or cysts
  • Cancer
  • Structural abnormalities

Risks

With a CT urogram, there is a slight risk of an allergic reaction if contrast material is injected. Reactions are generally mild and easily managed by medication. They include:

  • A feeling of warmth or flushing
  • Nausea
  • Itching
  • Hives
  • Pain near the injection site

A single CT urogram carries no risk of developing secondary malignancy, but multiple tests or radiation exposures may cause a slightly increased cancer risk compared with the general population. However, the benefit of an accurate diagnosis far outweighs this risk.

If you are pregnant or think that you may be pregnant, tell your doctor before having a CT urogram. Though the risk to an unborn baby is small, your doctor may consider whether it's better to wait or to use another imaging test.

How you prepare

Before a CT urogram, tell your doctor if you:

  • Have any allergies, particularly to iodine
  • Are pregnant or think you might be pregnant
  • Have had a previous severe reaction to X-ray dyes
  • Are taking any medications, such as metformin (Fortamet, Glucophage, Glumetza), nonsteroidal anti-inflammatory drugs (NSAIDS), anti-rejection drugs or antibiotics
  • Have had a recent illness
  • Have a medical condition, including heart disease, asthma, diabetes, kidney disease or a prior organ transplantation

In order to expand (distend) your bladder, you may be asked to drink water before a CT urogram and not to urinate until after the procedure. However, depending on your condition, guidelines about eating and drinking before your CT urogram may vary.

What you can expect

Before your CT urogram, a member of your health care team will:

  • Ask you questions about your medical history
  • Check your blood pressure, pulse and body temperature
  • Ask you to change into a hospital gown and remove jewelry, eyeglasses and any metal objects that may obscure the X-ray images

During a CT urogram

For a CT urogram, you usually lie on your back on an exam table, though you may be asked to lie on your side or stomach. Straps and pillows may be used to help you maintain the correct position and keep still during the exam. You may be asked to change positions during the CT urogram.

An IV line will be placed into a vein in your hand or arm through which the X-ray dye will be injected. You may feel a warm, flushed sensation when the dye is injected, and a metallic taste may appear in your mouth for a minute or two. The contrast material may briefly make you feel like you have to urinate.

Before your exam begins, the table will move quickly through the scanner to determine the correct starting position for your scans. For your actual CT urogram, the table will then move slowly through the machine while the images are taken. If needed, the machine may make several passes.

You'll hear slight buzzing and clicking sounds while the machine takes pictures. To keep the images from blurring, you'll be asked to hold your breath for a few seconds during the scanning.

After the CT urogram is complete, you'll be asked to wait while the technologist ensures the images are good enough quality for an accurate evaluation.

After a CT urogram

When your CT urogram is complete, the IV line is removed from your arm and the IV entry point is covered with a dressing. You may then return to your normal activities.

Results

A doctor who specializes in reading X-rays (radiologist) will review and interpret the X-ray images from your CT urogram and send a report to your doctor. Plan to discuss the results with your doctor at a follow-up appointment.


Content from Mayo Clinic