CT urogram: everything you need to know about this urinary tract exam

CT urogram: an examination of the kidneys, ureters, and bladder

A CT urogram, also known as a CT urography or urological CT scan, is performed in a medical imaging clinic or hospital on an outpatient basis. 

It uses X-rays to observe the urinary tract, specifically: 

• the kidneys ;
• the ureters (the tubes connecting the kidneys to the bladder);
• the bladder.

It may be performed with or without the injection of an iodine-based contrast agent, depending on the reason for the examination. 

The device consists of a large ring through which the examination table slides. Inside, an X-ray tube rotates around the body to capture images, without the patient feeling a thing.

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From diagnosis to follow-up: when a CT urogram is required

Pain, blood in the urine, infection: when the scan helps reach a diagnosis

A CT urogram may be prescribed to identify the cause of a symptom or to locate an abnormality.

It is primarily used in the following cases:

• a renal colic : sudden, unilateral lower back pain;
• a hematuria : presence of blood in the urine;
• a suspicion of kidney stones ;
• recurrent urinary tract infections , especially when they are resistant to treatment;
• an abnormality detected by ultrasound or physical examination.

It can also be used to perform an assessment of the urinary tract before surgery or following an abdominal or lower back injury.

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Follow-up CT urography for identified tumors or stones

CT urography can also be used to monitor a condition or abnormality that has already been diagnosed, such as a stone or a tumor.

For example, it may be requested as part of the follow-up for kidney or bladder cancer to measure tumor progression over time and adjust treatment if necessary.

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Preparing for a CT urogram: medical history to report

Before your appointment, it is important to report:

• a pregnancy that is ongoing or possible;
• any allergies known, particularly to an iodinated contrast agent;
• a metformin treatment (diabetes medication): whether to continue or interrupt it depends on your kidney function and will be decided by the medical team.

A creatinine test is required before the exam for patients with known kidney disease, high blood pressure, or diabetes. It ensures that the contrast agent can be injected safely.

Aside from these precautions, preparing for a urological CT scan is straightforward. Fasting is generally not required unless specifically instructed by the imaging center. Remember to bring your prescription and any previous imaging or lab results.

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A quick, multi-phase exam

A CT urogram typically lasts between 15 and 20 minutes. Depending on whether an injection is required, the procedure may involve up to four stages:

1. Positioning. The patient lies on their back and removes any jewelry or metal objects. An IV line is inserted if an injection is planned.
2. Initial non-contrast images. This series helps identify potential stones, which are more visible without contrast agent.
3. Injection of the iodinated contrast agent. The agent is injected intravenously. A temporary feeling of warmth throughout the body or a metallic taste in the mouth is common and harmless.
4. Post-injection images at various intervals. Several series are performed to observe the tissues and then the excretion of the agent through the urinary tract.

The exam is painless. You will need to remain still and hold your breath a few times during each series of images.

What is the purpose of an iodinated contrast agent injection?

Injecting a contrast agent is not always necessary; it depends on the reason for the exam. 

• Without a contrast agent, imaging allows for the visualization of basic anatomy and fixed structures such as kidney stones and hematomas.
• With a contrast agent, it allows for the analysis of soft tissues, blood flow, and functional aspects such as the flow of urine into the bladder.

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After a CT urogram: no special monitoring required, results sent to the referring physician

No special monitoring is required after a CT urogram. It is simply recommended to stay well-hydrated in the hours following the exam to help eliminate the contrast agent.

The images are analyzed by a radiologist, who writes a report sent to the referring physician. The turnaround time ranges from a few hours to a few days, depending on the center.

If the report indicates an abnormality, the referring physician will explain the results to the patient. If necessary, they will suggest further testing or a referral to a specialist.

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A second opinion to better understand your CT scan results

Once you have your results, additional insight can help you gain clarity before moving forward. 

A urologist second opinion can be useful when:

• the report mentions an abnormality you would like to better understand;
• you want a second specialized look before committing to a treatment;
• several additional tests are proposed and you are unsure about the next steps;
• surgery is being considered following the results.

The urologist will be able to review your file with a fresh perspective to supplement your doctor's opinion, without calling it into question.