Urodynamic testing is any procedure that looks at how well the bladder, sphincters, and urethra are storing and releasing urine. Most urodynamic tests focus on the bladder's ability to hold urine and empty steadily and completely. Urodynamic tests can also show whether the bladder is having involuntary contractions that cause urine leakage. A health care provider may recommend urodynamic tests if symptoms suggest problems with the lower urinary tract. Lower urinary tract symptoms (LUTS) include urine leakage frequent urination painful urination sudden, strong urges to urinate problems starting a urine stream problems emptying the bladder completely recurrent urinary tract infections Urodynamic tests range from simple observation to precise measurements using sophisticated instruments. For simple observation, a health care provider may record the length of time it takes a person to produce a urinary stream, note the volume of urine produced, and record the ability or inability to stop the urine flow in midstream. For precise measurements, imaging equipment takes pictures of the bladder filling and emptying, pressure monitors record the pressures inside the bladder, and sensors record muscle and nerve activity. The health care provider will decide the type of urodynamic test based on the person's health information, physical exam, and LUTS. The urodynamic test results help diagnose the cause and nature of a lower urinary tract problem. Most urodynamic tests do not involve special preparations, though some tests may require a person to make a change in fluid intake or to stop taking certain medications. Depending on the test, a person may be instructed to arrive for testing with a full bladder.