Urodynamic Study
The urodynamic study is a diagnostic method composed of a series of procedures whose objective is to reproduce the patient's urinary symptoms, measuring all the physiological variables involved in urination, to detect possible alterations in the function of the lower urinary tract.
General Description
The urodynamic study, or urodynamics, is a diagnostic technique used to evaluate the functioning of the lower urinary tract, specifically the urinary sphincter, bladder, and urethra. Urodynamics primarily studies the dynamics of urine storage and evacuation.
In essence, it is a method of provoking the vesicourethral function, meaning it involves provoking and reproducing the patient's symptoms to observe and simultaneously measure different physiological variables, such as bladder capacity and pressure, the pressure exerted by the sphincter, or the urine flow that can occur, among others.
When is it indicated?
The urodynamic study is performed on patients who suffer from any type of urinary incontinence, difficulty urinating, pelvic pain, or pelvic organ prolapse. The goal is to detect any functional alterations in the urinary tract and diagnose the corresponding condition.
How is it done?
A urodynamic test is composed of different tests or phases:
- Uroflowmetry: The patient urinates into a device called a flowmeter, which measures the volume urinated, the urination time, and the flow time to record the urinary flow rate (the strength of the urine stream) in milliliters per second. This study is usually complemented with an ultrasound to measure the post-micturition residue left in the bladder.
- Cystomanometry: The function of bladder filling is studied. For this, electrodes are placed in the bladder and around the anus to record activity during the procedure. Then, a catheter is inserted through the urethra into the bladder, and liquid is introduced while measuring intravesical pressure and the detrusor muscle pressure of the bladder (the muscle that pushes urine into the urethra). Another catheter introduced through the rectum measures intra-abdominal pressure. The results are displayed in a graph with colored lines showing the three measured pressures, the amount of liquid infused, and the presence of urine leaks.
- Pressure-flow study: When the patient feels the urge to urinate, filling is stopped, and the bladder voiding phase begins: the patient must urinate (without removing the catheters or sensors) while the same pressures are recorded again, and the urine flow is measured.
Risks
Although not common, a urodynamic study carries a risk of urinary infection or urethral injury due to the insertion of catheters into the bladder and rectum.
What to expect from a urodynamic study
Before starting, the patient should undress and wear the gown provided at the medical center. During the uroflowmetry, the patient must urinate as they normally would, i.e., without excessive pressure and until they feel that the bladder is emptied. If an ultrasound is performed after urination, the patient lies on the exam table, gel is applied to the pelvic area, and the ultrasound transducer is moved while observing the images on the monitor.
The electrodes and catheter required for the next phase of the study are placed with the patient lying on the table, after disinfecting the urethral opening. This procedure may be uncomfortable or unpleasant, especially for male patients, but it is generally not painful. During filling, the patient may be asked to cough or bear down with the abdomen. During voiding, it is normal to feel some burning, as the catheter remains in place. It is very important not to interrupt urination.
Once the study is finished, the catheters are removed, and the patient can go home as usual. The total duration of the study is usually between 30 and 45 minutes. An antibiotic is likely to be prescribed to prevent infection. It is also normal to feel a burning sensation when urinating for the first time after the test, and in some cases, the urinary symptoms the patient had may worsen in the following days, but this is a temporary situation.
Specialties that request the urodynamic study
Urodynamics is performed in the urology specialty.
How to prepare
The night before the test, it is necessary to use an enema to empty the rectum. It is also preferable to attend the test with the urge to urinate in order to perform the uroflowmetry. Additionally, to prevent possible infection, the doctor may recommend taking an antibiotic beforehand. Furthermore, the patient must sign an informed consent form.
