What is a Urodynamic Test?

A urodynamic test is carried out on someone with specific urination problems in order to evaluate the problem and help assess the cause. This test is ordered for people with blocked urine flow or urine leakage problems. The urodynamic test involves urinating into a container while urine volume and urine flow rate are measured.

In a normal urinary tract, several organs, nerves and muscles work together to accumulate, store and excrete urine. The first organs of the urinary system, the kidneys, collect urine and filter out waste products. Urine then passes through the ureters to the bladder, and from there, it is excreted via the urethra. Also involved in this process are pelvic floor muscles and sphincter muscles, which help prevent urine leakage from the bladder. Nerves located in the bladder receive and send signals about the state of the bladder, such as when it is becoming full and when it needs to be emptied.

Dysfunction in the muscles, nerves or organs therefore can cause a range of urinary tract problems, such as incontinence, frequent urinary tract infection, difficulty urinating, painful urination or the inability to empty the bladder completely. These problems have a variety of causes, including injury, illness, age or pregnancy. A urodynamic test is used to determine the cause of bladder problems or to provide information that, along with other test results, will aid in diagnosis.

Urodynamic testing can be a procedure that is simple or complicated, depending on how much diagnostic information is required. On the simple end of the scale, a patient might be asked to urinate while a medical professional listens. A more complicated test involves catheterization of the test participant to fill the bladder with a defined amount of liquid, after which the participant is asked to empty his or her bladder. Testing urinary tract function might involve evaluating how fast the bladder empties, how much urine remains in the bladder after emptying or how much liquid the bladder can retain without leakage.

An abnormal result from a urodynamic test might include one or more of several states. For some people, the problem is an urgent need to urinate or an inability to retain urine even if the bladder contains only a small amount. If an abnormally high amount of fluid is retained in the bladder after urinating, urine flow from the bladder might be impeded or blocked. Alternatively, the muscles that force the bladder to contract during urination might be weakened, preventing proper contraction.

In most cases, a urodynamic test does not require any special preparation. The test sometimes must be performed with a full bladder, so the participant might be asked to avoid urinating for several hours prior to the test. Urodynamic testing is not dangerous or painful, but it can be difficult or embarrassing for many people, because it involves urinating in the presence of one or more members of a clinical staff.