What is the best radiologic test to diagnose kidney stones?
Noncontrast computed tomography (CT) scan or ultrasound are the tests of choice for imaging patients with suspected kidney stones.
Advantages of CT include much greater sensitivity for small stones, no intravenous contrast, ability to detect uric acid stones (which are radiolucent on standard x-rays), and the potential to diagnose other causes of flank/abdominal pain if no stones are found.
The main drawback with CT scans is the radiation exposure. If a patient requires serial radiologic evaluation, a KUB (kidneys, ureters, and bladder) x-ray is preferred, but only if the stone of interest can be adequately visualized.
Ultrasound can identify hydronephrosis and document stones, but it is not as sensitive or specific as CT.
Ultrasound is clearly the preferred imaging method in pregnant women, and many clinicians prefer to use it in children to avoid excessive radiation.
