CT Urography: Uses, Procedure, Risks, and How to Prepare

What Is CT Urography?

CT (computed tomography) urography or urogram is a medical imaging technique used to detect the function and abnormalities of the urinary tract, which includes the urinary bladder, kidneys, and ureter (a pair of tubes that carries urine from the kidneys to the bladder). CT urography is commonly used in the diagnosis of conditions such as hematuria, kidney or gall bladder stones, and cancer of the urinary tract. It is usually a painless procedure and causes minor harm to the overall body.

What Is the Difference Between CT Scan and CT Urography?

CT scan and CT urography are the imaging tests used to diagnose several medical conditions in the urinary system. The main difference between a CT scan for the urinary tract and a CT urogram is the use of contrast dye. The contrast dye is used in the case of CT urography and not in the case of CT scan.

How Does CT Urography Produce Images on the Screen?

Computed tomography takes the help of X-rays in order to capture images of internal body parts, which are afterward computed by a computer. The moment the patient is inside the CT unit, these X-rays circle the body and yield a series of images. The merit of this technique lies in generating images in multiple directions. The images created are two-dimensional, which the computer processes and arranges to obtain three-dimensional pictures of the urinary tract.

What Factors Should Be Considered While Recommending CT Urography in Hematuria Patients?

CT urogram is advised for hematuria patients based on two factors: the visibility of blood in the urine and the patient's age. CT urography is highly accurate in diagnosing hematuria in urothelial cell carcinoma (UCC) and largely prevents the possibility of false-positive results.

Unenhanced CT (the technique without the use of contrast dye) is advised for patients younger than 40 with microscopic hematuria and a low risk for UCC. It is also recommended for patients younger than 40 with visible hematuria and a low risk for UCC. Enhanced CT urography is advised in patients older than 40 with visible hematuria and a high risk for urothelial cell carcinoma (UCC).

Patients with a history of smoking, chemical exposure, and previous pelvic radiation therapy may require CT urography. Patients with abdominal pain and who have undergone cystectomy with urinary diversion may require urography.

How Do I Get Ready for a CT Urogram?

Before your CT urogram, your doctor will check your vital signs, like your temperature, pulse, and blood pressure. They will also ask you some important questions, such as:

Do you have any health conditions?

Are you allergic to contrast dye or iodine?

Could you be pregnant?

Are you taking any medications, like diabetes medicine (Metformin), pain relievers (NSAIDs), antibiotics, or blood thinners (Warfarin)?

You might need a blood test before the CT urography procedure to make sure the right contrast dye is used.

If you have a contrast dye allergy, your doctor may give you a steroid to take the night before and the morning of your test. You will probably also take an antihistamine before the scan. Your doctor will prescribe these if needed.

For a smooth CT urogram preparation, your healthcare provider will guide you through each step. In the end, your doctor will give you clear instructions on how to prepare for your CT urogram—be sure to follow them carefully!

What Are the Instructions Given to Hematuria Patients Before CT Urography?

Before the CT urography scan, the patient is advised to take water for the hydration of the kidneys and the distention of the urinary bladder and ureter. Patients may be asked to walk around the room or roll on the procedure table, which helps in the mixing of contrast material and urine. For some patients, Furosemide or saline is administered through an intravenous line (IV), which encourages the flow of urine.

Step-By-Step Guide to CT Urography:

1. Before the Scan:

When you arrive, you'll fill out a short form and talk with the radiographer, who will explain what to expect. This is a good time to ask any questions.

You'll usually change into a hospital gown. If you have a dressing gown, bring it to wear over the hospital gown while you wait.

Before the scan, you'll need to remove any jewelry or metal objects near the area being scanned, as metal can interfere with the images.

A radiographer will place a small tube (cannula) into a vein in your arm. When it’s time, they will take you to the scanning room.

2. In the Scanning Room:

The CT machine is big, and you might find it like a very big doughnut.

You might receive a medicine called furosemide through your cannula to help produce clearer images of your kidneys. Right after, you'll get an injection of contrast dye. This dye might make you:

Feel warm or flushed for a minute or two.

Taste something metallic in your mouth.

Feel like you need to pee, even though you don’t. This feeling passes quickly.

The CT scanner is open, but some people feel a little claustrophobic. Let the radiographer know if this worries you.

3. During the Scan:

You'll lie on a moving table, usually on your back, but sometimes on your front. The radiographer may use foam cushions to help position you.

They will leave the room but will talk to you through an intercom and watch you through a window.

As the scanner takes pictures, the table will slowly move in and out of the machine. The scan is painless but can feel uncomfortable since you need to stay still. If you get stiff, tell the radiographer.

You may hear a whirring noise and be asked to hold your breath at times. The radiographer might also stop the scan and ask you to walk around or go to the bathroom to empty your bladder before continuing.

If you need to change positions, they will guide you through the intercom or come into the room to help.

4. After the Scan:

• When the scan is over, the radiographer will lower the table so you can get up. If you received contrast dye, you'll need to stay for 15 to 30 minutes to make sure you feel okay.

• Before you leave, the radiographer will remove the cannula. You can go home, eat, drink, and return to normal activities soon after.

How Is CT Urography Performed in Hematuria Patients?

• Straps may be used to hold the patient in the required position. Infants and children may need sedation as they may be unable to remain still throughout the procedure, though certain high-speed scanners may benefit the children. Pediatric patients may generally be accompanied by their parents. However, for safety reasons, the accompanying adults must wear a lead apron to prevent radiation exposure.

• Movement during the scan may affect the quality of the images. A non-contrast CT of the kidneys is taken to find out the renal calculi. Some patients may require contrast materials (a special dye), which depends on the type of examination.

• A contrast material (iodine-based) is administered into the body through an intravenous line (IV) with a high-resolution nephrogenic phase and a delayed excretory phase (five to ten minutes) to help in detecting tumors and filling defects. When the dye is injected, the patients may feel slight warmth throughout the body.

• Once the patient is placed in the appropriate position, the table would slowly slide within the CT unit for scanning. Patients will most likely go through the machine several times. Depending on the type of CT, patients may be asked to hold their breath for a few seconds to get better images. Any motion, including breathing and body movements, may lead to artifacts in the images.

What Are the Protocols Followed in CT Urography?

CT urography protocols are classified based on the number of boluses of contrast materials used. They are:

• Single Bolus - Single bolus is recommended for hematuria patients with increased risk of UUT-UCC, renal stones, and cancer. It involves three series of images: an unenhanced series for stone detection, a nephrogenic series for renal mass detection, and an excretory series for UUT-UCC detection.

• Double Bolus - It is recommended for follow-up in patients with bladder cancer. In a double bolus, the contrast material available for the nephrogenic and excretory phases is less than in a single bolus. Hence, it does not clearly show renal carcinoma and UUT-UUC.

• Triple Bolus - It is recommended for the assessment of kidney donors and patients who had percutaneous nephrolithotomy procedures. The volume of contrast material used in this procedure may split, and it affects the accuracy of the image. Hence, it is not recommended for investigation in hematuria patients.

What Risks Come With a CT Urogram?

CT urograms are usually safe, but like other imaging tests, they use a small amount of radiation to take pictures. Some possible risks of CT urography include:

• Cancer Risk: Radiation exposure from imaging slightly increases the risk of cancer, but the increase is too small to measure.

• Allergic Reactions: Some people may have mild or serious allergic reactions to the contrast dye.

• Bruising or Swelling: You might have some bruising or swelling where the needle was placed for the injection.

• Kidney Problems: In rare cases, the contrast dye can affect kidney function. That’s why your doctor checks your blood test results before the scan to make sure your kidneys are healthy.

• Pregnancy Concerns: If you're pregnant or think you might be, let your doctor know. CT scans are usually only done during pregnancy if absolutely necessary.

If you’re worried about these risks, talk to your doctor. They can answer your questions and help you decide what’s best for you.

Conclusion:

CT urography replaces other imaging techniques in the detection of patients with hematuria in UCC because of its accuracy in the excretory phase. For patients with visible hematuria, CTU is the first line of diagnostic tests. Traditionally, hematuria is diagnosed with an intravenous pyelogram. It is now replaced by CT urography because the accuracy rate of CT urography is higher than that of an intravenous pyelogram (IVP) in microscopic hematuria. However, with this technique, the diagnosis is made swiftly, which helps frame a treatment plan for better outcomes.

Key Takeaway/ Note from iCliniq:

CT urography is a powerful imaging tool that provides detailed X-ray scans of your kidneys and urinary tract to detect issues like stones, infections, or tumors. While the procedure is generally safe, it involves contrast dye and mild radiation exposure. Preparing properly—such as fasting, removing metal objects, and informing your doctor about allergies—ensures accurate results.

At iCliniq, you can consult top radiologists and urologists online, get expert second opinions, and clarify any concerns about the procedure—all from the comfort of your home! Stay informed, stay healthy.