Spatial Distribution and Timing of Transmitted and Reflexly Generated Urethral Pressures in Healthy Women

Abstract

We localized the temporal and spatial distribution of pressures in the urethra to identify their contribution to continence. With the data obtained we resolved the timing between the passively transmitted and actively generated urethral pressures. Data were obtained from 11 healthy female volunteers, with a mean age of 22 years. Simultaneous measurements of bladder and urethral pressures were taken from subjects during the Valsalva maneuver and coughing, and then holding with the subject in the supine, standing and sitting positions. The ratio of urethral to bladder pressure increase and the latency between these pressure increases were analyzed. A biphasic pressure distribution results from coughing with subjects in all positions. The first phase occurs at the normalized distance of 10 to 15 per cent from the bladder neck, where the ratio of urethral to bladder pressure increase is 0.8. The second phase occurs at 60 to 70 per cent of the urethral length and has a 1.5 to 1.7 ratio of urethral to bladder pressure increase, indicating the presence of pressure magnification. Simultaneous latency measurements indicate that the pressure increase in the urethra precedes that of the bladder by 240 plus or minus 30 msec. in the region that exhibits maximum pressure magnification. These results indicate that a fast-acting contraction occurs in the distal third of the urethra, which contributes reflexly to the compressive forces of the proximal urethra, thereby preventing urine loss during stress.

Ultrasound Evaluation of Dynamic Responses of Female Pelvic Floor Muscles

“…Research using kinesiological EMG also supports our 2D ultrasound analysis. In continent women there is recruitment of PFM motor units (Deindl et al 1993) and an increase in intra-urethral pressure (Constantinou & Govan 1982) prior to an increase in intra-abdominal pressure (IAP) during a cough. However there are altered PFM activation patterns during a cough, measured by EMG in women with SUI compared to healthy volunteers (Deindl et al 1994), with shorter activation periods, lack of response or paradoxical inhibition.…”

Lumbopelvic Dysfunction and Stress Urinary Incontinence: A Case Report Applying Rehabilitative Ultrasound Imaging

“…30 The treatment program was designed to address motor control deficits in the TrA and PFMs, based on both clinical findings and reports of delayed or altered contractions of these deep trunk muscles in those with lumbopelvic dysfunction 11,21,27,28,30 and incontinence. 1,6,20 The addition of pelvic-floor-elevating exercises may have assisted with the lumbar stabilization exercise regimen, based on the findings by Critchley,8 who found that a cocontraction of the PFMs with a TrA muscle contraction increased the thickness of the TrA muscle more than an isolated TrA contraction in normal subjects. Given that this patient demonstrated significant symptomatic and functional improvement in 8 weeks suggests that her SIJ region pain and SUI may have been more related to altered motor control strategies than significant strength loss.…”

“…18,19,32,34 Delayed or altered activation of these deep trunk muscles has been demonstrated in those with lumbopelvic dysfunction 11,21,27,28,30 and SUI. 1,6 A cadaveric study by Pool-Goudzwaard et al 31 demonstrated that simulated tension of the female PFMs significantly stiffened the sacroiliac joints (SIJ) by 8.5% and produced a backward rotation of the sacrum. The authors suggest that increased activity of the PFMs may help compensate for inadequate pelvic stability and improve the ability to transfer load through the lumbopelvic region.…”

The Role of Altered Connective Tissue in the Causation of Pelvic Floor Symptoms

“…The rise in pressure within the urethra precedes the rise in pressure in the bladder by 160-240 milliseconds (Enhorning 1961, Constantinou and Govan 1982, van der Kooi et al 1984, Pieber et al 1998). This means, that the increased pressure within the urethra during stress must be due to an active muscle contraction and cannot be a passive transmission of the abdominal pressure.…”