How are kidney stones diagnosed?

Your first diagnosis of kidney stones often occurs when you see your doctor or go to an emergency room because you are in great pain. Your doctor or an emergency medicine specialist will ask you questions and examine you. After you pass a stone, your doctor may give you another exam to find out whether you are likely to get kidney stones again.

Tests to diagnose kidney stones

Your doctor may do one or more of the following tests to help diagnose kidney stones, see where they are located and find out if they are causing or may cause damage to the urinary tract.

• A noncontrast spiral computed tomography (CT) scan is the preferred test for kidney stones. It is a special type of CT scan that moves in a circle.
• An intravenous pyelogram (IVP) is an X-ray test that shows pictures of the urinary tract, including any kidney stones.
• A retrograde pyelogram may be done if the IVP or CT scan does not provide a diagnosis.
• Urinalysis and urine cultures test your urine.
• An abdominal X-ray (KUB) gives a picture of the kidneys, the bladder and the tubes that connect the kidneys to the bladder (ureters).
• An ultrasound exam of the kidneys (ultrasonogram) is the preferred test for pregnant women.

Tests to find out the type of stone

Determining the type of your kidney stone will help with treatment decisions and measures to prevent stones from forming again. Tests you may have include:

• A medical history and physical exam.
• Stone analysis. Your doctor may ask you to collect stones by straining your urine through a fine-mesh strainer or fine gauze. He or she will then determine what type of stone it is.
• Blood chemistry screen, to measure kidney function, levels of calcium, uric acid, phosphorus, electrolytes and other substances that may have caused the stone to form.
• Urine collection for 24 hours, to measure volume, pH, calcium, oxalate, uric acid and other substances that may have caused the stone to form. This is a test you may do at home.