Kidney Stones

Diagnosis

X-ray of kidney stones

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Mayo Clinic physicians use the following imaging tests to diagnose kidney stones:

• Spiral computerized tomography (CT) scan
  Spiral CT is a type of high-speed CT imaging that uses a series of thin X-ray beams to produce two-dimensional images of the organs. Spiral CT imaging scans the abdomen and can reveal tiny kidney stones that may not appear on conventional X-rays or traditional CT scans.
• CT urogram. Dye containing iodine is injected into a vein, and a CT scan is taken of the kidneys, bladder and ureters. The dye helps outline the drainage systems of the kidneys.
• Abdominal X-ray (KUB)
  An abdominal X-ray may be used to obtain images of the urinary system and identify a kidney stone. However, not all stone types show up on an abdominal X-ray.
• Intravenous pyelography (excretory urogram)
  This imaging study can be useful in determining the location of kidney stones in the urinary system and can define the degree of blockage caused by a stone. Contrast dye is injected into a vein in the patient's arm, and a series of X-rays are taken as the dye moves through the kidneys, ureters and bladder.
• Ultrasound
  Ultrasound tests use high-frequency radio waves to create a picture on a computer screen that enables physicians to inspect a patient's internal organs. An ultrasound is a painless, noninvasive test. Mayo Clinic physicians use ultrasound less frequently than spiral CT or excretory urogram to diagnose kidney stones because ultrasound may not detect small stones, especially those outside the kidneys that may be lodged in the ureter or bladder. However, ultrasound imaging is often the first diagnostic test performed in patients for whom radiation exposure is of concern, such as children and pregnant women.