Reviewed by: Missy Nolan
Although urodynamics sounds a bit like "aerodynamics," it doesn't have anything to do with cars. They are similar, however, in that aerodynamics involves taking careful measurements to examine the forces that affect objects moving through air. Urodynamics also uses careful measurements, but these are used to understand the various factors involved when you empty your bladder. Urodynamics can help you get to the bottom of what's causing your incontinence.
What Is Urodynamics?
Urodynamics is a group of tests used by doctors to find out how your lower urinary tract is functioning. Your physician can decide the types of urodynamic tests needed based on your individual health information, physical exam, and lower urinary tract symptoms, such as incontinence. The following are types of urodynamic tests:
- Urethral pressure profile
- Voiding pressure study
- Postvoid residual volume
The Types of Urodynamics Tests
Each of the tests mentioned above measures a different part of your bladder function, so we'll dive into what they assess.
A cystometric test is used to measure the pressure inside the bladder at various points in the urination process. The test can look at how much urine the bladder can hold and how full it is when you first feel the urge to go. For most people, the pressure that creates the urge to urinate disappears once you go to the bathroom. If you experience this pain all the time, still feel it after you go, or don’t feel it all, this test may be for you.
To do the test, your doctor will first use a catheter to empty your bladder. Sometimes, electrodes are placed near the rectum and a smaller catheter with pressure monitoring placed inside. For women, another catheter may be placed in the vagina to look at abdominal pressure.
Once the bladder is empty and catheters are placed, your doctor will slowly fill the bladder with warm, sterile water. You'll be asked if you feel any bladder sensations and when you feel the urge to urinate.
A smaller catheter may be placed in the bladder to measure the pressure while you empty your bladder. Your doctor will ask you to cough and strain to see how much pressure it takes to cause urine leakage. At the end of the test, they'll take a look at how the pressure changes as urine leaves your bladder. If leaking occurs during the test, it may be a sign of stress incontinence.
Doctors recommend the electromyography test when they think the issues you're having are related to nerve or muscle damage. With this test, your doctor will place a few small electrodes near the rectum and urethra to record the electrical activity of muscles as you use them during urination. This test can detect potential nerve signaling problems between your urethra and bladder.
Urethral Pressure Profile
Your doctor might recommend a urethral pressure profile if they think your urethral sphincter — the area that controls your urine flow — is too weak or too strong. Usually, this procedure follows another type of urodynamic test, such as cystometry.
A medical provider will insert a bladder catheter and move it back and forth along the length of the urethra to document urethral pressure and length. Urethral pressure is the pressure inside the urethra applied by the urethral walls. Some pressure is needed by the urethral walls, but too much prevents urine from coming out and too little might lead to unexpected releases.
The procedure can also help your provider calculate the maximum urethral closure pressure. This pressure is determined by finding the difference between the maximum urethral pressure and the pressure within the bladder while voiding (also known as intravesical pressure).
Your doctor may suggest a uroflowmetry test if it's suspected that your bladder muscles are weak or something is blocking proper urine flow. Typically, your doctor will recommend arriving with a full bladder for accurate results. During this two-part test, you'll urinate into a special toilet or funnel with a container for collecting the urine that measures your flow rate as you empty your bladder. The equipment will create a graph that shows changes in urine flow as you're voiding.
Voiding Pressure Study
For the voiding pressure study, also known as the pressure-flow study, a medical provider will check how the bladder functions as it empties. Once your bladder is completely full, you'll urinate into a unique commode chair, while wearing a void pressure catheter. From there, your medical provider will review your bladder pressure and flow rate.
Postvoid Residual Volume
The postvoid residual volume tests measure how much urine is still in your bladder after you go. There are two ways to take this measurement. Here's what you can expect for either scenario:
For this procedure, you'll empty your bladder right before the test. Then, a nurse will insert a catheter to drain out any additional urine that's still remaining. They'll measure how much was taken out to help determine if you have a UTI, issues with incontinence, or something else.
The ultrasound test is often the preferred option because it's painless and less invasive. Like the previous test, you'll void first. Then, a nurse will hold an ultrasound wand on your stomach and roll it around to measure your bladder with ultrasonic waves. You'll see images on a monitor as measurements are taken, which your doctor can use to determine how much urine is still there.
The last and final procedure is videourodynamics. It's not a standard test mainly because you can obtain much of this data from the other tests. Because of this, most people see it as an unnecessary expense. Nonetheless, this special X-ray can help your doctor better understand any abnormalities in the size and shape of your bladder and urinary tract.
During the procedure, a medical provider will fill the bladder with a contrast solution. As the bladder fills, your nurse will likely:
- Ask when you first feel your bladder filling, how it feels during filling, and when you feel like you need to go
- Record different pressure measurements
- Determine how much urine the bladder holds
- Ask you to cough and strain to check for bladder leaks
Reasons Why People Get a Urodynamics Test
If you're experiencing bladder leaks, a urodynamics test can collect data related to your bladder function, sphincters, and urethra to see how they hold and release urine. This information can help your provider understand the root cause of any issues you have with incontinence. These tests, more specifically, should reveal the cause of problems related to:
- Bladder leaks
- Frequent urinary tract infections
- The need to go too often
- The need to void suddenly
- Weak urine flow
- Intermittent urine flow (the flow of urine stopping and starting)
- The inability to fully empty your bladder
Benefits of a Urodynamics Test
A urodynamics test is the first step in finding treatment available for any incontinence issues. The tests narrow down exactly what the problem is, so it can be addressed. Once that's known, your provider can go over any medication or therapy approaches that may help minimize or manage your specific issue. Rather than just living with incontinence, you may be able to find a solution for it. However, not all incontinence issues can be resolved with treatment. Thankfully, there are reliable incontinence products that can help you feel confident in any situation and continue living your active life worry-free.
Getting Answers: Urodynamic Tests
If you're having any issues with leaks or pain in your bladder, your doctor will likely recommend a urodynamics test. These tests help put a diagnosis behind your incontinence issues, so you can get the proper help you need. There's always a sense of relief when you at least know what's going on with your bladder.
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While pursuing her nursing degree, Missy aced her medical courses and was hired as a chiropractic assistant. After her second child was born, Missy left the chiropractic office and became a full-time medical writer. Since then, she's written thousands of articles about everything from urinary incontinence to neurological conditions and digestive health. Missy also appreciates a holistic approach toward wellness and is well-versed in the benefits of combining treatments such as meditation, sound therapy, and acupuncture with traditional Western medicine.