Urodynamic Studies

Urodynamic studies are used to determine the function and health of the bladder, sphincter, or urethra, and can provide the most complete and accurate diagnosis for a range of urinary issues. A urologist may recommend a urodynamic study if a patient is experiencing lower urinary tract symptoms, such as frequent or painful urination, urine leakage, or difficult initiating urination or emptying the bladder completely.

There are a variety of urodynamic tests, and which ones a urologist orders depends on his patient's symptoms. Many of these diagnostics focus on the bladder and its ability to empty fluid: Imaging techniques and other measurements gauge urine flow, the bladder's ability to fill and retain fluid, and how well it releases urine. Other tests monitor muscular activity and nerve control, bladder and urethra pressure, and whether the bladder is involuntarily contracting.

What to Expect from Urodynamic Testing

Many urodynamic studies require a patient to arrive with a full bladder. The patient is asked to empty her bladder in a private room, where a scale measures the amount of urine expelled. After this, she may be asked to sit in a reclining chair with stirrups so that a small catheter can be inserted. (Most patients describe this process as uncomfortable rather than painful.) The catheter is used to fill the bladder with sterile saline solution to gauge how well the bladder holds and empties fluid. Finally, the patient may be asked to urinate with or without the catheter still in place.

Types of Urodynamic Studies

The following are urodynamic studies currently used for diagnosis today:

Uroflowmetry is the use of a uroflowmeter to determine the rate of urine flow. The device measures the amount of urine, the rate of release, and how long it takes for the flow rate to reach its peak. The resulting data tells a doctor whether the patient's bladder muscles are weak or strong. Uroflowmetry also reveals urine-flow obstruction, which can signify other issues.

Multi-Channel Video Urodynamics utilize X-rays or sound waves to produce images of the lower urinary tract during bladder filling and emptying.

Cystometry refers to the use of a cystometrogram (CMG) to measure bladder pressure when it is full and when the patient needs to void. During this procedure, a catheter empties the bladder then fills it with warm fluid. A second catheter is inserted into the rectum or vagina in order to measure the pressure of the intra-abdomen.

Electromyograms measure the bladder muscle signals. Because bladder muscles need to signal properly for the bladder to function properly, any anomalies may indicate an underlying neurological disorder. This procedure is often required in conjunction with a CMG.

Voiding Cystourethrogram is an imaging test that takes contrast-dye enhanced X-rays of the lower urinary tract when the bladder is both empty and full. This test allows a doctor to determine if an obstruction is present, and can help determine whether there are any underlying structural variances related to the symptoms.

Pressure Studies are often performed along with a CMG and are used to measure pressure at a leakage site. This test is particularly useful for examining stress incontinence, in which leakage occurs in response to abdominal pressure on the bladder.

Post-Void Residual is a measurement of the amount of urine left in the bladder after it has emptied. This test is done either with an ultrasound or a catheter that leads up to the bladder.


Gray M. Traces: Making Sense of Urodynamics Testing -- Part 13: Pediatric Urodynamics. Urologic Nursing. September 2012;32(5):251-274.

Khai-Lee T., Chee-Kwan N. Urodynamic studies in the evaluation of young men presenting with lower urinary tract symptoms. International Journal Of Urology [serial online]. May 2006;13(5):520-523.

Sekido N., Himotsu S., Kawai K., Shimazui T., & Akaza H. How many uncomplicated male and female overactive bladder patients reveal detrusor overactivity during urodynamic study?. International Journal Of Urology. October 2006;13(10):1276-1279.

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