Overview. Urodynamic studies are considered to be among the most definitive tests for determining the source of symptoms involving the lower urinary tract, including the bladder and the urethra. A variety of urodynamic tests can help to evaluate the bladder and urethra and how they are functioning in their task of storing and releasing urine. These tests can help to pinpoint the anatomic or neurologic source of symptoms such as leakage, frequent urination, problems starting a stream, dribbling, painful urination, problems completely emptying the bladder, and recurrent urinary tract infections.
Types. The types of tests that are administered depend on the patient’s symptoms. Most are focused on the ability of the bladder to empty completely, the consistency and pressure of the stream, and the ease with which it starts and stops. The tests often incorporate imaging equipment to film urination, and monitors that record the pressures of the bladder and urethra. There are tests to measure the ability of the bladder to fill with and store urine, and tests that assess the release of the urine, as well as the post-void residual (any urine left in the bladder after the voiding process is complete). Urodynamic studies include:
Uroflowmetry . A uroflowmeter measures the flow rate of urine to determine both the speed at which it is released (average and peak rates) and to see how long it takes to get to its fastest point. An abnormal result suggests a weak bladder muscle or obstructed urine flow.
Cystometry. A cystometrogram (CMG) measures bladder pressure and its fullness at the point that the patient feels the urge to urinate. This procedure uses a catheter to first empty the bladder completely, then to fill it slowly with warm water. A second catheter is placed in the rectum or vagina to measure intra-abdominal pressure.
Electromyelogram. An electromyelogram (EMG), often performed with a CMG, measures the signals in the muscles involved in bladder function to assess any potential neurological disorder that may be playing a role in the symptoms.
Pressure Studies. Also during CMG, a measurement is taken of the pressure at the point where the leakage occurs. This is particularly helpful in evaluating stress incontinence – leakage in response to abdominal pressure to the bladder such as from coughing or sneezing. Similarly, a urethral pressure profile employs a special catheter to measure sphincter closure pressure and urethral competence during filling, voiding, and abdominal pressure.
Voiding Cystourethrogram. This imaging test affords a view of the lower urinary tract while the bladder is being filled and emptied as a way to see any obstruction or anatomical abnormalities.
Multi-Channel Video Urodynamics. Video urodynamics use X-ray equipment or sound waves to provide a real-time evaluation of the interplay of the lower urinary tract functions during filling and emptying.
Measurement of Post-Void Residual. The amount of urine left in the bladder after voiding can be measured by inserting a catheter into the urethra, or with ultrasound imaging.
