What is and what is a urodynamic study for?
“And how to urinate in a complex and dynamic process of filling and emptying, characterized by the phenomena of relaxation and contraction, records, data and very clarifying graphs can be obtained through this ambulatory analysis”, says Dra. Carmen González Enguita.
The head of the Urology Service at the Fundació Jiménez Díaz University Hospital, a doctor and surgeon, explains that the urodynamic study includes different measurements; in particular, the pressure of the bladder and the abdominal cavity, or the activity of the pelvic floor muscles.
“To assess the pressure in the bladder organ and the abdominal cavity, two very thin probes are used; one is inserted into the rectum through the anus and the other into the bladder through the urethra. We study their behavior during the filling and emptying of urine”, he describes.
“In a very general way, we can point out that we accurately measure a series of variables, such as the flow of urine that a patient is able to produce with each voluntary contraction of the bladder, the bladder capacity, with the tension that is generated, also the pressure exerted by the sphincter, etc.,” he explains.
If what is being measured is the activity of the pelvic floor muscles, electrodes are placed in the form of a patch or adhesive stuck to the perineum area, the lower part of the pelvic floor, where the buttocks sit.
The complete urodynamic study is done in a maximum of sixty minutes.
“At this time we cause the bladder to be filled with physiological serum, which we introduce through the bladder probe. trying to reproduce a natural filling. We will observe the patient’s symptoms when the bladder must be relaxed and still”, he continues.
“The test result will show us a graph of different colored lines that reflect the pressures inside the bladder, the detrusor muscle, the rectum, the amount infused and if urine leaks during filling. bladder,” he adds.
These are fundamental data that can offer us the keys to the atypical behavior of bladder activity, of the abdominal cavity or of the pelvic floor muscles.
Sometimes, before starting the urodynamic study, a specific test called flowmetry
The patient is made to urinate in the office to measure their voiding volume (bladder capacity), the complete time it takes to empty the bladder, the maximum pressure that this voiding flow reaches or whether the emptying is complete.
It also measures whether there is any post voiding residue (PVR) or the amount of urine left in the bladder after the emptying phase, which will be analyzed using a probe or using an ultrasound image.
Flowmetry is considered a basic urodynamic study, as it collects valuable data from a natural, not artificial, urination. Pressures and urinary flow data are recorded, which will be taken into account during diagnosis and treatment.
Dr. Carmen González Enguita
In which situations or diseases is a urodynamic study done?
When a man or woman wants to urinate, because the bladder is full, the body sends a signal to the brain through the nervous system, which immediately goes to work to find the right place.
Usually, given the usual circumstances of the environment, a washroom with a toilet is sought.
The brain then sends a new command through the spinal cord to the bladder to contract and empty this kind of bag of fluid through the urethral sphincter, which carries urine to the outside if not there are other obstacles.
In this same sense, if there are diseases or common processes that generate problems in urination, modifying the patient’s behavior in these beds, a diagnostic test with a urodynamic study will be carried out.
“We need to know with graphics and data the details of the urinary incontinence (UI), from the overactive bladder (VH), as micturition urgency, Urgency UI and high micturition frequency; and also, of the micturition difficulty at the time of emptying, the chronic pain of the pelvis or the repercussion of the pelvic organ prolapse (POP)”, points out the urologist.
Thanks to this type of tests, a long series of aspects are detected and related.
“The exact topography of a urinary obstruction, the percentage of urine flow that is retained or the type of incontinence that is suffered. Also, this test is very important when an artificial sphincter will be placed and allows us to study other associated urinary diseases”, he explains.
Likewise, it allows the study of other associated diseases and is decisive when an intervention to place an artificial sphincter will be performed.
Sometimes the urodynamic study is completed with a video view of urination.
“We call it video urodynamics. To do this study, a contrast medium (radiopaque substance) is introduced into the bladder. We will observe the information through a screen, such as the morphology of the bladder and urethra, as well as bladder capacity”, he emphasizes.
What abnormal circumstances occur in the bladder filling phase?
“That the urine can go up from the bladder to the kidneys through the ureters, what is called passive vesicoureteral reflux; or that the patient exerts an abdominal force (coughing, laughing, etc.), or during the emptying of the bladder (active vesicoureteral reflux)”, he answers.
“Also, a loss of urine can occur while the bladder is being filled, either as a result of its low capacity or the uninhibited contractions of the detrusor muscle”, he completes.
And in the phase of emptying the bladder?
“Due to the impossibility of starting urination or the difficulty of opening the bladder neck”, he points out.
With the urodynamic study, and the video urodynamics supplement, you get a graphic and dynamic visualization of the entire emptying process.
“We further analyze the morphology of the urethra during the entire journey of urine, which is very important in cases of urethral stenosis. In addition, it is very effective when there are post-missionary residues in the bladder after the emptying phase ends”, he emphasizes.
Information and data of the patient who needs a urodynamic study
The urodynamic study does not require a previous hospital admission, as it is done on an outpatient basis. It is not necessary to come fasting, but it is advisable to use an enema for the evacuation of stool in the descending colon and rectum.
The test is not painful, but it is a procedure that requires some invasive action: inserting a catheter up to the bladder, from the male or female urethral meatus; and another anorectal probing to measure pelvic floor muscle activity.
It should be emphasized that probing is not a risk factor at the micturition and rectal level.
“It is essential to go to the outpatient appointment with a bladder full of fluid and with the desire to empty it, although without reaching the point of not being able to hold it, since it is usual to do a flow measurement before proceeding to the urodynamic study”, notes in the patients’ visual notebook.
During the study, you cannot urinate until the nursing professional so indicates.
“It is also not advisable to use antibiotics to carry out the urodynamic study or flowmetry, although, sometimes and in certain Urodynamics Units, it can be part of the protocol for this type of intervention”, he points out.
In addition, this study is usually accompanied by a series of questionnaires that gather information about the urinary problems that the patient is experiencing: the symptoms or the evolution of the disease.
“At the same time, we usually ask that a voiding diary be written for a period of three days, in which everything linked to the pathology to be examined will be noted,” he comments.
PADTest, which quantifies the amount of involuntary urine that soaks into a pad or diaper: the device is weighed at the beginning and end of the test.
The clinical history, various diagnostic tests and data, including questionnaires, will provide as a result the functional study of the patient.
“Said study can be obtained immediately or after a few days. It will depend on the possibility that the specialist doctor evaluates all the documentation and draws up the relevant medical report”, he concludes.
Patients should know that the urodynamic study is a functional study that will be integrated with the other data, tests and information that the doctor needs to establish a good diagnosis and treatment.
You must be properly informed through your doctor of everything you need to know if you have been instructed to perform a urodynamic study. It is better to go to the diagnostic test well prepared.
It must be remembered that not all medical teams have specialized equipment to carry out these types of tests and, therefore, cannot carry out these urodynamic studies.
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Dr. Carmen González Enguita, head of the Urology Service at Fundació Jiménez Díaz Hospital
FIRST CHAPTER: “Urodynamic study: with the bladder open to technological scrutiny“