Kidney Stones - Diagnosis

Physical Examination

The doctor will press against abdominal areas for tender locations that might indicate the presence of the stone.

Medical History

The patient's age is a significant factor. Kidney stones that occur in children and young patients are more apt to result from inherited problems that cause cystine, xanthine, or, in some cases, calcium oxalate stones. In adult patients, calcium stones are most common.

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A medical history may help predict which crystal has formed the stone. The doctor will need to know the following:

Any previous kidney stone attacks
Histories of cancer, sarcoidosis, or small bowel disease
Any medications being taken, including non-prescription substances, particularly high doses of vitamins D or C and calcium-containing antacids

Imaging Techniques

Various imaging techniques are helpful in determining the presence of kidney stones. The best approach uses spiral (or helical) computed tomography scans. It is not always available, however, in which case ultrasound or standard x-rays are usually performed. If no stones show up but the patient has severe pain indicative of kidney stones, the next step is an intravenous pyelogram.

X-Rays. A standard x-ray of the kidneys, ureters, and bladder may be adequate as a first step for identifying many stones, since most are opaque on x-rays. Calcium stones can be identified on x-rays by their white color. Cystine crystals also can show up on x-rays.

Spiral (or Helical) Computed Tomography. A computed tomography (CT) scan called a spiral or helical CT scan is currently the best method for diagnosing stones in either the kidneys or ureters. It is fast, noninvasive, and provides detailed accurate images of even very small stones. If stones are not present, it can often identify other causes of pain in the kidney area. It is superior to x-rays, ultrasound, and intravenous pyelogram--the test that was the previous standard for detecting kidney stones. Experts hope spiral CT will eventually be able to reveal the stone's composition.

Ultrasound. Ultrasound can detect translucent uric acid stones and obstruction in the urinary tract. It is not useful for finding very small stones, but some research indicates that it may be a useful first diagnostic step in the emergency room to help predict the likelihood of a stone, including suspected stones in children.

Intravenous Pyelogram. With intravenous pyelogram (IVP), the patient is injected with a dye, and x-rays are taken as the dye enters the kidneys and travels down the urinary tract. IVP is invasive but, until recently, was the most cost-effective method for detecting stones. Where it is available, spiral CT is now preferred, since it gives a faster diagnosis, is more accurate, and it is similar in cost. In any case, IVP should not be used on patients with kidney failure. There is a risk for an allergic reaction to standard dyes, although newer less allergenic ones are becoming available.

In the procedure intravenous pyelogram (IVP), the patient is injected with dye.X-rays are taken as the dye travels through the urinary tract. This procedure isdone to confirm the presence of kidney stones, although some stones may be too small to see.