How Is a CT (Computed Tomography) Urogram Performed?

What is a CT urogram?

A CT (computed tomography) urogram is a non-invasive radiological examination of the urinary system. The doctor injects a mildly radioactive tracer compound into your vein, which then allows the radiologist to view the structure and function of the kidneys and bladder using the CT scanner.

A computed tomography (CT) urogram is an imaging test used to evaluate the urinary system, which includes the kidneys, ureters (tubes that carry urine from the kidneys to urinary bladder), bladder, and urethra (urinary tract).

A CT urogram is performed by injecting a contrast dye (iodine contrast solution) into the vein in the hand or arm. The dye flows into the kidneys, ureters, and bladder outlining each of these structures. X-rays are used in a CT urogram to generate multiple thin-slice (5 mm) images of the urinary system at specific time intervals, starting just above the kidneys and ending just below the pubic bone. These images are then directed to a computer and are reconstructed into detailed two-dimensional (2D) images. These images can help the radiologist see the urinary system and assess if it is working well or identify any abnormalities.

Why is a CT urogram done?

A computed tomography (CT) urogram allows accurate visualization of the kidneys, ureters, bladder, and urethra. The size and shape of these structures can be assessed to determine if they are functioning properly and to look for any signs of diseases.

A CT urogram may be recommended if a patient is experiencing signs and symptoms that may be related to a urinary tract disorder such as:

A CT urogram helps to diagnose urinary conditions such as:

How is a CT urogram performed?

Preparation for a computed tomography (CT) Urogram:

• To expand (distend) the bladder, the patient may be asked to drink a certain amount of water and not urinate before the procedure. However, depending on the patient’s condition, guidelines about eating and drinking before a CT urogram may vary.
• Before a CT urogram, the patient must inform the doctor if they
  • Have any allergies, particularly to iodine.
  • Had previous severe reaction to X-ray dyes.
  • Are pregnant or think that they might be pregnant.
  • Are taking any medications, such as antibiotics, metformin for diabetes, nonsteroidal anti-inflammatory drugs (NSAIDs), or anti-rejection drugs or blood thinners.
  • Have any recent illness.
  • Have a medical condition, including heart disease, asthma, diabetes or kidney disease, or a prior organ transplantation.

Procedure for a CT urogram:

Usually, the patient lies on their back on an exam table attached to the CT scanner, although sometimes they may lie on their side or must change positions during a CT urogram. Straps and pillows may be used to help maintain the position and keep still during the exam.

• An intravenous (IV) line will be placed into a vein in the hand or arm through which the X-ray dye will be injected.
• The contrast dye medium may make the patient
  • Feel warm and flushed for 1-2 minutes.
  • Have a metallic taste in the mouth.
  • Feel like passing urine; this feeling is common and passes soon.

The scanner is a large doughnut-shaped machine with a large hole in the middle through which the table slides. Before the exam begins, the table will move quickly through the scanner to determine the correct position for the scans. During the actual CT urogram, the table will move slowly through the machine while the images are taken. If needed, the machine may make several passes.

• You may notice slight buzzing and clicking as the machine takes pictures. To keep the images from blurring, the patient must to hold their breath for a few seconds during scanning. 
• The scan is painless but can be uncomfortable because one has to stay still, and some people may feel claustrophobic.

What are the complications of a CT urogram?

A computed tomography (CT) urogram is generally safe. Some possible risks associated with a CT urogram include:

• Allergic reaction: There is a slight risk of an allergic reaction to the contrast dye material injected during a CT urogram. Reactions are generally mild and can be managed easily by medication. Allergic reactions that may occur include:
• Pain, bruising, and swelling near the site of injection
• Radiation hazard: A single CT urogram has no risk of secondary malignancy, but multiple tests and radiation exposures may slightly increase cancer risk. However, the benefits outweigh this risk.
• Kidney damage: There is a small risk that the contrast medium used can affect the kidneys. The patient’s kidney function is checked before the test.
• Pregnancy: If the patient is pregnant or might be pregnant, although the risk to the unborn baby is very low, the doctor may consider using another imaging test or waiting.