AUA Summit - What is Urodynamics?


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What is Urodynamics?

Urodynamic studies (UDS) test how well the bladder, sphincters, and urethra hold and release urine. These tests can show how well the bladder works and why there could be leaks or blockages.

There are many types of urodynamic tests. A health care provider may recommend one or more based on your symptoms, but they are typically performed together as one test.

These tests, which are explained on the following pages, are all UDS tests:

Why Would I Need Urodynamics?

Urodynamics help find the cause of problems related to:

Your health care provider will talk with you about your symptoms. Then the provider should give you a physical exam and start with simple urine tests.

If more information is needed, your provider may suggest UDS and possibly x-rays. Your urologist will create a treatment plan based on what they learn from the studies. Additional tests will help to clarify the problem.

To prevent infection, you will often be given an antibiotic before and/or after your test. You will also be asked to arrive with a full bladder.

How Does the Lower Urinary Tract Usually Work?

Your lower urinary tract includes the bladder and the urethra and the prostate (if you are born male).

The bladder is a balloon-shaped organ that stores urine, which is made in the kidneys. It’s held in place by pelvic muscles in the lower part of your belly.

The bladder is relaxed when it isn’t full. Nerve signals in your brain let you know that your bladder is getting full. When it is full, you feel the need to release urine. When you are at the toilet the brain then tells the bladder muscles to squeeze (or "contract"). This forces the urine out of your body through your urethra.

Your urethra has muscles called sphincters. They help keep the urethra closed so you don’t leak before its time to pass urine. These sphincters open up to release urine when the bladder contracts.


Cystometry, or cystometrogram, with a pressure flow study is part of urodynamic testing (or UDS). These tests measure how well the bladder functions and can help diagnose problems related to urine control. These can be incontinence, difficulty emptying the bladder, overactive bladder, obstructions or frequent infections.

Cystometry is used to measure how much urine the bladder can hold. It also measures pressure inside the bladder, and how full it is when you have the urge to go.

For more information please visit our article about Cystometry.


Electromyography (EMG) tests the electrical activity of the muscles and nerves of the pelvic floor. If a urinary problem may be related to nerve or muscle damage or abnormal movement of the pelvic floor muscles, EMG is used. Small sticky sensors are placed near the urethra or rectum to record muscle and nerve activity. This test measures the strength and activity of muscles and nerves in and around the bladder and sphincters.

Urethral Pressure Profile

To learn about the strength of your urethra and its outlet, more testing may be done. The catheter with a sensor might be moved back and forth in the urethra. This will record information about the urethra and outlet. This test is called a “urethral pressure profile” (or UPP).


Uroflowmetry measures how much urine comes out, and how fast. It is done in two-parts. Your doctor may suggest this test if you have trouble urinating, or have a slow stream.

By measuring the average and top rates of urine flow, this test can show a blockage such as an enlarged prostate. You will be asked to arrive with a full bladder for best test results.

For more information please visit our article on Uroflowmetry.

Voiding Pressure Study

A pressure flow study measures the pressure in your bladder as you urinate. It also measures the urine flow rate. This study helps to find a block in the bladder from prostate enlargement or when combined with the CMG may identify a weak bladder or another issue.

When you feel your bladder is full, you’ll be asked to urinate into a special chair. This time, you’ll urinate with a void pressure catheter (a “manometer”) in place. The catheter is small and your urine will flow around the catheter. This tool measures how well your bladder muscles work as it empties.

After the studies, some people feel a burning sensation or pain or may see blood in the urine. This goes away within a day or two. If you continue to see blood in your urine or have a fever, please tell your doctor.

After the Procedure

These tests may leave you with slight discomfort for a few hours when urinating. It helps to drink several glasses of fresh water after the tests. You may find comfort with a warm, damp washcloth placed over the urethral opening.

Your health care provider will discuss test results with you. After you learn more, you and your health care provider will decide on the best treatment plan.

More Information

  • What are results from this test telling you?
  • Will I need other tests to explain my problem?
  • What are my next-steps for treatment?

Updated November 2023. 

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