Kidney stones tests may include a stone analysis, screening of blood chemistry, urine collection over a 24 hour period, and a physical exam. Tests that take images of the kidneys, such as an ultrasound, computed tomography (CT) scan, or x-ray, are also used as kidney stones tests. Different types of tests are conducted for proper diagnosis in determining the type of stone, its location, and whether or not it may damage the urinary tract.
The purpose of kidney stones tests to establish the type of kidney stone helps doctors make decisions about the best possible treatment. These tests may also help to prevent a recurrence of the kidney stones. Doctors may also conduct a stone analysis to identify the type of stone. Patients collect the stones by straining the urine through fine gauze.
Urine cultures and a urinalysis are two types of kidney stones tests that check the urine for the presence of kidney stones. Various components of the urine are measured to verify the level of acidity and blood that might be present. Urine cultures also reveal if a urinary tract infection (UTI) exists.
Blood tests measure kidney function and the level of substances, such as electrolytes, calcium, and uric acid, that might result in the formation of kidney stones. Volume, oxalate, calcium, and other substances are measured in urine that is collected during a 24 hour period. A physical exam and full medical history may also determine risk factors for developing more kidney stones.
When performing imaging tests, physicians tend to prefer a noncontrast spiral CT scan to look for stones. In this test, a scanner circles the body to provide better images of organs. In addition to providing different views of the kidneys, this test takes only half the time of a regular CT scan. Views of the ureters, which are the tubes connected to the kidney, are also visible during this type of CT scan for kidney stones.
Largely replaced by the noncontrast spiral CT scan, one type of x-ray for kidney stones is an intravenous pyelogram (IVP). This test shows the shape and size of the ureters and kidneys, as well as their position. A dye is injected into an arm vein that shows up in a series of x-ray pictures of the urinary tract.
Another type of kidney stones test is the abdominal x-ray for kidney stones, known as a KUB (kidneys, ureters, and bladder). It provides a picture of the organs of the urinary tract to identify the existence of a kidney stone. The KUB x-ray may also occur several weeks after a kidney stone is passed.
In some cases, an ultrasound may be used to look at the kidneys. The ultrasound is generally used for women who are pregnant so as to protect the fetus from harmful radiation. A picture of the kidneys is produced through reflected sound waves.
If standard kidney stones tests fail to reveal the problem, a retrograde pyelogram test can be performed. During this procedure, dye is injected into the ureters instead of the vein. This can sometimes provide more definitive results, but is more invasive than the other procedures.