Hilton P, Stanton SL: Measurement of urethral pressure using microtransducers: results in asymptomatic women and in women with real stress incontinence. Br J Obstet Gynaecol 90: 919, 1983. The main cause of true stress incontinence is the anatomical change caused by weakness in the pelvic floor support tissue. This, in turn, is associated with vaginal delivery, abdominal surgery or other injuries. In urodynamic studies, intraurethral pressure was found to be low in women with stress incontinent [88,89]. The data suggest that at least two a-adrenergic receptor agonists have been shown to be effective in clinical trials, norefedrin and midodrine, which increase intraurethral pressure. It should be noted that the decrease in intraurethral pressure contributes only slightly to the overall clinical picture, which limits the use of a pharmacological agent only to milder cases [90,91]. The advantages of balloon catheters in measuring urethral pressure are that they avoid dependence on orientation. In the past, however, technical problems have made the balloons too large, resulting in a dilation effect on the urethra. This leads to an overestimation of urethral pressure.
In addition, the length of the balloon is also important. If the balloon is too long, pressure fluctuations along the urethra are averaged. Recent balloon catheters have overcome these challenges (Pollak et al., 2004). The urethral pressure profilometry (UPP) method was popularized by Brown and Wickham in 1969 using small catheters with lateral openings through which fluid is continuously infused (Brown and Wickham, 1969). Simultaneous bladder and urethral pressure is measured when the catheter is slowly retracted along the urethra. The urethral pressure transmitter measures the fluid pressure needed to lift the urethral wall of the catheter-side holes, thereby increasing circumferential and radial tensions induced by the presence of the catheter in the urethra and slow urethral profusion. Therefore, urethral pressure is defined as the fluid pressure required to open a closed urethra (Abrams et al., 2002). Accurate measurements are recorded only in cases where the urethra is stretchable and can therefore create a perfect seal. So far, no research team has been able to reliably measure transmission pressures in the urethra during exercise. The transmission ratio measurement proposed for EUI specific urodynamic diagnosis has been discontinued as it is influenced by many parameters and is not well correlated with SUI degree [4-6]. It is performed by filling the bladder until a leak from the urethra is observed or the capacity of the bladder is reached in the absence of contraction of the detrusor. Ideally, the technique for performing abdominal leakage pressure (cough or valsalva) should be standardized and performed in exactly the same way each time to allow comparison between patients and make follow-up studies meaningful.
There is a lot of controversy about the technique of this test. These include the size of the catheter, the volume of the bladder, the type of provocation, the positioning of the patient, how to determine the actual increase in pressure, and the best way to perform the test in the presence of genital prolapse. The commonly used technique is – with a 6 French dual sensor microsensor in the bladder, a subtracted filling cystometry is performed up to a bubble volume of 150 to 200 ml. To perform pressure from the vanishing point of the bladder neck, the filling cystometrogram is performed at a slower filling rate, usually 25 ml / min. Assuming that there are no abnormalities in bladder compliance, pressure measurements at the vanishing point are performed at this volume. In a sitting position, the patient performs a progressively more vigorous Valsalva maneuver until a leak occurs. The lowest bladder pressure at which a leak occurs is considered abdominal leakage pressure. If patients do not leak with a valve or repeated cough, the catheter is removed from the bladder and provocative maneuvers are repeated, measuring abdominal pressure via an intravaginal or intrarectal catheter. In some patients, pressure can occur at very large volumes and high pressures. Once a bubble pressure of 40 cm H2O is reached, the study can be completed, as an ongoing filling above this pressure can be dangerous. Several parameters have been shown to influence abdominal leakage point pressure measurements.