Urodynamics (Bladder Control) Testing

WHY this test is done

Urodynamics assesses how the bladder and urethra are performing their job of storing and releasing urine. This test is typically performed for women who have problems with incontinence (involuntary loss of urine), urgency, or frequent urination.  During the test, specialized electronic equipment takes readings from a tiny catheter inserted into the bladder.

Urodynamic testing is the most precise way to measure how the bladder is functioning and can be used to determine what type of incontinence you have. There are many reasons for involuntary loss of urine or bladder dysfunction, and this test will give a great deal of information about what is causing the problem. Urodynamic tests help determine how well your bladder and sphincter muscles work, and can help explain symptoms such as:

  1. Incontinence
  2. Frequent urination
  3. Sudden, strong urges to urinate
  4. Problems starting a urine stream
  5. Painful urination
  6. Problems emptying your bladder completely
  7. Recurrent urinary tract infections
WHAT you should do to prepare

Prior to testing, a urinalysis and urine culture must be obtained to ensure there is no infection. You must have this urinalysis and urine culture completed PRIOR to your visit so that we can do the entire evaluation in one visit. This can be done with your local doctor, at our office, or at a Quest laboratory convenient to you. The person who makes your appointment can set this up for you. It is important that you are on time, and you should expect to be at our office for 1-2 hours.

Please arrive at our office will a full bladder. Do not urinate until you are in the testing suite and asked to do so. No other preparation is needed.

WHAT to expect during the procedure:
Taking the Test

Most urodynamic testing focuses on the bladder's ability to empty steadily and completely. It can also show whether the bladder is having abnormal contractions that cause leakage, if you have difficulty starting a urine stream, how hard you have to strain to maintain it, whether the stream is interrupted, and whether any urine is left in your bladder when you are done. 

Uroflowmetry (Measurement of Urine Speed and Volume)

A uroflowmeter automatically measures the amount of urine and the flow rate—that is, how fast the urine comes out. You will be asked to urinate privately into a toilet that contains a collection device and scale. This equipment creates a graph that shows changes in flow rate from second to second so that we can measure the peak flow rate and how many seconds it took to get there. Results of this test will be abnormal if the bladder muscle is weak or urine flow is obstructed.

Measurement of Post-Void Residual

After you have finished urinating, you may still have some urine, usually only an ounce or two, remaining in your bladder. The remaining urine is called the post-void residual.  To measure this post-void residual, we will insert a tiny catheter into the urethra. A post-void residual of more than 200 mL, about half a pint, is a sign of a problem. Even 100 mL, about half a cup, requires further evaluation. However, the amount of post-void residual can be different each time you urinate.

Cystometry (Measurement of Bladder Pressure)

A cystometrogram (CMG) measures how much your bladder can hold, how much pressure builds up inside your bladder as it stores urine, and how full it is when you feel the urge to urinate. After the post-void residual has been measured, another catheter will be placed in the vagina to record pressure there as well. Your bladder will be filled slowly with sterile water. During this time, you will be asked how your bladder feels and when you feel the need to urinate. The volume of water and the bladder pressure will be recorded. You may be asked to cough or strain during this procedure. Involuntary bladder contractions can be identified.

Measurement of Leak Point Pressure

While your bladder is being filled for the CMG, it may suddenly contract and squeeze some water out without warning. The manometer will record the pressure at the point when the leakage occurred. This reading may provide information about the kind of bladder problem you have. You may also be asked to apply abdominal pressure to the bladder by coughing, shifting position, or trying to exhale while holding your nose and mouth. These actions help us evaluate your sphincter muscles.

Pressure Flow Study

After the CMG, you will be asked to empty your bladder. The catheter can measure the bladder pressures required to urinate and the flow rate a given pressure generates. This pressure flow study helps to identify bladder outlet obstruction that men may experience with prostate enlargement. Bladder outlet obstruction is less common in women but can occur with a fallen bladder or, rarely, after a surgical procedure for urinary incontinence. 


Getting the Results

Results and possible treatments will be discussed with you immediately after the test. 


What to expect after the procedure

You will have no discomfort after the procedure and may resume all normal activities.



How long does the procedure take?
The actual test takes anywhere from 15-30 minutes. Some women reach full bladder capacity with a small amount of water and leak early on. Others require a much larger volume (and a longer time to fill) than others. Filling out the questionnaire, getting ready for the test, doing the test and discussing the test often take up to two hours of office time, so please plan accordingly.

Can I have a guest in the room?
You may bring someone with you if you desire. They can be in the room during the testing, or, if you prefer, join you just for the discussion of results.

Is this test painful?
This test is not painful other than the discomfort of having a full bladder.

I once had a catheter inserted and it was very uncomfortable. Is this catheter the same?
The catheter we use for testing is significantly smaller than a Foley catheter, and in addition, no balloon is inflated to hold it in place. It is rare for someone to even be aware of its presence.

I feel uncomfortable losing urine in front of people. Who will be in the room?
The only people in the room will be your physician or physician assistant and a medical assistant to operate the equipment. The room is designed for you to lose urine (there is no carpeting!) and while it may seem strange to you, it is the best way to determine what your problem is so we can fix it. While some women consciously (or subconsciously) hold back from losing urine, please do your best to act as if we are not there.