Finding the right tests…
Emergency services available 24 x 7
Emergency services available 24 x 7
Finding the right tests…
CT Scan
CT KUB usually means the plain, dye-free scan doctors use for kidney stones, but this version is different on purpose. Contrast is given through a vein to examine the kidneys, ureters, and bladder for something other than a stone, most often a suspected tumor or mass in the urinary tract. The contrast is timed as it moves through the kidneys, which helps characterize a growth rather than just locate it. If your doctor already suspects a stone, they're more likely to order the plain CT KUB instead, since stones show up clearly without dye and contrast can actually make small ones harder to see.
The radiologist looks at the kidneys, ureters, and bladder for a mass, thickening, or other abnormality, using the contrast pattern to judge how a growth is behaving. Stones, if present, are also noted. Findings are written into a report your doctor uses to plan any next steps.
KUB stands for kidneys, ureters, and bladder. The plain version of this scan is the well-known one doctors use for suspected kidney stones, since stones are dense enough to show up without any dye. This contrast version exists for a different reason: characterizing a mass or abnormality that a plain scan can spot but not fully explain.
Timed contrast through the kidneys shows how a growth takes up blood supply compared to normal kidney tissue, which is genuinely useful for telling a tumor apart from a cyst or a normal variant. This detail is not something a plain scan can provide.
- Any past reaction to injected contrast dye - Kidney disease or reduced kidney function, since contrast is cleared through the kidneys - Any chance of pregnancy, given this scan uses x-ray radiation
If your doctor specifically suspects a stone, ask whether the plain CT KUB might be the more appropriate scan instead, since contrast isn't needed to see a stone and can occasionally make small ones harder to spot.
The well-known, plain version of CT KUB is indeed the standard for suspected kidney stones, since stones show up clearly without dye. This contrast version is ordered for a different reason, usually to characterize a mass or abnormality rather than to find a stone.
Contrast shows how a mass takes up blood supply over time, which helps tell a tumor apart from a cyst or normal tissue. A plain scan can spot that something is there but often can't say much about what it actually is.
Probably not on its own. The plain CT KUB is the standard first choice for suspected stones, since contrast isn't needed to see them and can occasionally make small stones harder to spot. Ask your doctor which version fits your specific situation.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Iodine-based contrast is cleared through your kidneys, so people with significant kidney disease face added risk from the dye. Tell your doctor about any kidney problems before this scan, since it's being done to examine the kidneys themselves.
Preparation depends on your specific case and protocol, so it isn't something to assume from a general description. Confirm with your doctor or the diagnostic centre what applies before your appointment.
Tell your doctor and technologist right away about any chance of pregnancy, since this scan uses x-ray radiation close to the pelvis. CT scans are generally avoided during pregnancy unless there's no safer alternative.
This scan focuses specifically on the kidneys, ureters, and bladder, with contrast timing built around how these structures take up blood supply. A broader abdomen scan covers more organs but may not be timed the same way for the urinary tract specifically.