Computerized tomography (CT) urogram

Overview

A computerized tomography urogram, also called a CT urogram, is an imaging exam used to look at the urinary tract. The urinary tract includes the kidneys, the bladder and the tubes called ureters that carry urine from the kidneys to the bladder.

A CT urogram uses X-rays to create multiple images, also called slices, of an area of the body. The image slices show bones, soft tissues and blood vessels. The images are sent to a computer that assembles them into a detailed flat image, also called a 2D image.

During a CT urogram, an X-ray dye, also called contrast material, is injected into a vein in the hand or arm. The dye flows into the kidneys, ureters and bladder and outlines each of these structures. X-ray pictures are taken at specific times during the exam. This allows your healthcare professional to see your urinary tract and check how well it's working.

Why it's done

A CT urogram helps a healthcare professional examine the kidneys, ureters and bladder. Your healthcare professional can see the size and shape of these structures to see if they're working as they should be. Your health professional also can look for any signs of disease in the urinary tract.

You may need a CT urogram if you have signs and symptoms of a urinary tract condition. This includes pain in the side or back or blood in the urine, also called hematuria.

A CT urogram may help diagnose urinary tract conditions such as:

• Kidney stones.
• Bladder stones.
• Serious infections.
• Tumors or cysts.
• Cancer.

Risks

With a CT urogram, there's a small risk that you could have an allergic reaction to the contrast material. Reactions are generally mild and may include:

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

Reactions can be treated with medicine. If you've had a reaction to contrast material in the past, your healthcare professional may prescribe medicine before you have a CT urogram.

Sometimes kidney function changes after a person gets contrast material for a CT urogram. This is usually temporary. Regular kidney function returns after 7 to 10 days in people who are affected.

A single CT urogram carries little risk of cancer developing from radiation exposure. But multiple tests or radiation exposures may cause a slightly increased cancer risk. Typically, the benefit of an accurate diagnosis far outweighs this risk. Work continues on ways to reduce radiation exposure during a CT urogram test.

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

How you prepare

Before a CT urogram, tell your healthcare professional 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 medicines, such as nonsteroidal anti-inflammatory drugs, also known as NSAIDs, antirejection drugs or antibiotics.
• Have recently been sick.
• Have a medical condition, such as heart disease, asthma, diabetes, kidney disease or an organ transplant.

You may be asked to drink water before a CT urogram and not to urinate until after the procedure. This expands the bladder. But depending on your condition, guidelines about what to eat and drink before your CT urogram may vary.

What you can expect

Before a CT urogram

Before your CT urogram, a healthcare professional may:

• 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.
• Place an IV line into a vein in the hand or arm. The X-ray dye goes into this line.

During a CT urogram

You lie on your back on an exam table for a CT urogram. Or you may be asked to lie on your side or stomach. Straps and pillows may be used to help you stay in the correct position and hold still during the exam. You may be asked to change positions during the CT urogram.

The X-ray dye is injected into the IV. You may feel a warm, flushed sensation when the dye is injected. You also may notice a metallic taste in your mouth for a minute or two. The contrast material may briefly make you feel like you have to urinate.

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

The machine makes slight buzzing and clicking sounds while it takes pictures. The technician may ask you to hold your breath for a few seconds during the scanning. This helps make sure the images are as clear as possible.

After the CT urogram is over, the technician checks the images for quality while you wait.

After a CT urogram

When the test is done, the IV line is removed from your arm. The IV entry point is covered with a dressing. Most people return to their usual activities after the test.

Results

A doctor who specializes in reading X-rays, called a radiologist, reviews and interprets the X-ray images from your CT urogram. The radiologist sends a report to your healthcare professional. Plan to talk with your healthcare professional about the results at a follow-up appointment.