A renal computed tomography (CT) scan is an imaging test that creates detailed pictures of the urinary system. It combines a series of X-rays taken from different angles with computer processing to generate cross-sectional images. These images show the kidneys, ureters, and bladder with a level of detail significantly greater than a standard X-ray. This allows for a thorough evaluation of these organs and their surrounding tissues.
Purpose of a Renal CT
A physician may order a renal CT scan to investigate a range of symptoms that suggest a potential issue with the urinary system. One common reason is the sudden onset of severe pain in the side or back, known as flank pain, which could indicate a kidney stone. The presence of blood in the urine (hematuria) is another indicator that prompts a closer look. Unexplained high blood pressure can also sometimes be traced back to problems with the arteries supplying the kidneys, which a CT scan can help evaluate.
In cases of physical trauma, a CT scan is used to assess the extent of any damage to the kidneys. The detailed anatomical views are also valuable for surgical planning. By creating a clear map of the kidney’s structure and its blood vessels, surgeons can prepare for procedures like tumor removal or kidney transplantation. These scans are also used for monitoring known conditions, such as tracking the size of a previously identified kidney cyst or tumor over time.
The Renal CT Procedure
Preparation for a renal CT scan depends on whether it will be performed with or without a contrast agent. For scans using contrast, a special dye makes certain tissues and blood vessels appear more clearly. Patients undergoing a contrast-enhanced scan may be asked to fast for a few hours and may need a blood test to check kidney function. Regardless of the scan type, it is recommended to wear comfortable, loose-fitting clothing without metal.
During the procedure, the patient lies on a motorized table that slides into the center of a doughnut-shaped CT scanner. The scanner’s X-ray tube rotates around the body, capturing images from multiple angles. The patient must remain very still and, at times, hold their breath to prevent blurring the images. If contrast dye is used, it is administered through an intravenous (IV) line, and it is common to feel a brief, warm sensation as the dye circulates.
The entire scan is quick, often completed in 10 to 30 minutes. After the scan is finished, the IV line is removed if one was used. Most patients can return to their normal daily activities immediately. For those who received contrast dye, it is recommended to drink plenty of fluids to help flush the agent out of their system.
Interpreting the Findings
After the scan is complete, a radiologist examines the images to identify any abnormalities within the urinary tract. One of the most common findings is kidney stones. CT scans can detect stones, revealing their precise size and location, which helps determine the best course of treatment. The images can also show signs of infection, such as areas of kidney inflammation (pyelonephritis) or abscesses.
The scan is useful for characterizing masses found in the kidneys. A radiologist can often differentiate between simple, fluid-filled cysts, which are typically benign, and more complex tumors that may require further investigation. Blockages within the urinary system, such as an obstruction in one of the ureters, can also be clearly identified. The images can also reveal congenital anatomical variations or issues with the blood vessels supplying the kidneys.