Patients who come to the hospital reporting incontinence or voiding issues are due for urological testing. However, which specific test they need will depend on what their symptoms are and what the doctor’s best judgment is.
The decision may not always be straightforward because each patient is different, and also because of the confusion around uroflowmetry and urodynamic testing; the two most common urological tests.
In this post, we will define each of these tests, establish what they do and who they are for, then finally break down the urodynamic testing process. This step-by-step analysis intends to explain how these two procedures are connected, and how we can maximize their potential to get the best results for all patients.
What is Uroflowmetry?
Uroflowmetry is the measurement of urine volume and speed. It is also known as the urine flow rate. It quantifies the amount of urine expelled in a certain period. ‘V’ is used to represent the volume, while ‘Q’ represents the maximum flow rate. The maximum flow rate is how fast the urine leaves the body.
During the uroflowmetry test, the patient urinates into a funnel-shaped device fitted with a scale connected to a computer. The scale sends readings to the computer, where the machine then creates a graph showing urine flow rate against time. The time it takes to get to the highest flow rate is the most significant value.
Uroflowmetry is also performed by recording the time it takes a patient to urinate into a calibrated container that accurately measures the volume of urine automatically.
This procedure does not require any anesthesia, is not invasive, and requires no catheterization. The patient will also be allowed to urinate in a private place.
What is Urodynamic Testing?
Urodynamic testing is not a single test, but a group of synergistic tests. Urodynamics, therefore, is a group of tests that allow accurate assessment of how well a patient’s lower urinary tract is functioning. The lower urinary tract comprises the urethra, urethral sphincters, bladder, and all the nerves that control the lower urinary tract. All of these components work together in the final stages of urine excretion.
Urodynamics focuses on the bladder's ability to hold urine and the steady expulsion of urine from the body through the urethra. The range of devices and techniques used to achieve this vary in precision and sophistication. Therefore, you can consider urodynamics a holistic method for assessing lower urinary tract issues, such as incontinence and voiding dysfunction.
It is usually prescribed by urologists and urogynecologists, but gynecologists may also request these tests for their patients.
How Do Uroflowmetry and Urodynamic Testing Compare?
From the information we have gained so far, we can see that urodynamic testing is an all-encompassing set of urological testing while uroflowmetry is a singular specific test. There is no definite distinction between the two tests because they complement each other, if not complete each other, to provide more comprehensive assessments.
In short, urodynamic tests usually include uroflowmetry as one of the core tests, and most uroflowmetry tests often need other urodynamic procedures in order to provide a complete picture of a patient’s issues.
We have covered what uroflowmetry tests measure and how they do it, but what are the tests included in urodynamic testing?
What is Involved in a Typical Urodynamic Test?
The number of tests requested in urodynamic testing will vary from patient to patient, but these are the four most common procedures: 1) Complex cystometrogram (CMG), 2) Electromyography (EMG), 3) Intra-abdominal voiding pressure study, and 4) complex uroflowmetry.
Complex cystometrogram with calibrated electronic equipment
Cystometric tests measure the amount of pressure that builds up in the bladder as it fills with urine, the volume of urine the bladder can hold, and finally, what volume and pressure signal the brain to give the urge to urinate.
The complex cystometrogram is an invasive test, requiring the use of catheters. The first catheter is used to artificially drain the bladder. The second catheter with pressure measuring electrodes is then placed in the empty bladder and connected to a manometer. A third catheter, similar to the second one, is placed in the vagina or rectum to record abdominal pressure.
Once all the catheters are in place, the bladder is filled with saline and the patient describes what they feel throughout the process. The pressure during the patient’s every state is precisely measured on an electronic device which then produces the cystometrogram.
Electromyography studies (EMG) of anal or urethral sphincter
Electromyography studies the electrical activity of the urethra and sphincter muscles and nerves. This technique uses special sensors that observe any abnormalities in the functioning of the muscles in the lower urinary tract.
The most common way electromyography is performed is by placing electrodes directly on the skin near the rectal opening. Although superficial, the technique is highly effective in determining whether or not disturbances are caused by neurological problems.
Intra-abdominal voiding pressure studies
Intra-abdominal voiding pressure is measured using the same catheters as in cystometric testing. The pressure recorded reflects the bladder pressure and is an indication of how much the patient strains to void their bladder.
If there is some kind of abdominal obstruction or muscular and nervous dysfunction, the voiding pressure may exceed the normal limit which will help pinpoint a possible issue. Voiding pressure studies are a direct method of urological testing and are similar to the cytometric tests described previously.
Complex uroflowmetry with calibrated electronic equipment
We have already discussed what uroflowmetry is, and how it is performed. It is worth noting that this test is one of the most common tests included in urodynamic testing.
This is perhaps one of the greatest reasons why the two are often assumed to be the same thing. But it is also a testament to how effective and crucial this test is. Uroflowmetry is often the first and most concise detector of urological problems, but due to the limited data it produces it often points to needing a complete urodynamics test.
The Urodynamics and Uroflowmetry Intersection
Uroflowmetry is a singular, specific test that falls within the four primary urodynamics components. Said a different way, uroflowmetry is a subset of urodynamics. The two cannot be compared because they simply supplement each other. A professional physician will determine when uroflowmetry should be conducted or when urodynamics should be conducted, and when it can be left out. Uroflowmetry is usually included within a urodynamics test.
Therefore, the two only seem synonymous because they are often together, but you do not need to perform them together, nor do you need to feel anxious about your doctor not requesting one or the other.
About BHN
For hospital systems and medical practices, BHN provides urodynamics nurse staffing and comprehensive urodynamics testing. BHN’s comprehensive urodynamics testing includes the nurse staffing, supplies, software, and urodynamics equipment in a single bundle, which makes deploying urodynamics very effective and cost efficient. If you need assistance with urodynamics testing or urodynamics staffing at your hospital or practice, please reach out to us.
