Urethral pressures during bladder filling.

Continuous simultaneous recordings of the urethral and intravesical pressures (pves) during medium fill cystometry (CMG) were performed in 1) twelve healthy fertile volunteers, 2) nine healthy postmenopausal volunteers, 3) nine genuine stress incontinent and 4) sixteen women with unstable detrusor. During the cystometry the urethral pressure rose in two stages. Approximately 70% of the maximum urethral pressure (MUP) rise occurred within the first minute. This was followed by a gradual increase to a maximum at the conclusion of the CMG. The bladder pressure showed a similar pattern with 10-20% of the intravesical pressure rise occurring during the first minute of the cystometry. Both active and passive forces seemed to participate in the MUP and maximum urethral closure pressure (MUCP) rise. This urethral pressure increment was found in all the women except the stress incontinent, reflecting deficient activity of the pelvic floor musculature in this category of patients. Changing position from supine to sitting increased the pves more than the MUP. Consequently a decrease in the MUCP was noted. The MUP increment during position change was due to both passive intraabdominal pressure (pabd) transmission and increased pelvic floor muscle activity but it was obviously not sufficient to maintain the pressure difference in any of the groups. Continuous recordings of the intraurethral pressure showed a significantly lower MUP in the postmenopausal and stress incontinent women both at rest and during the CMG. The group with unstable detrusor contraction showed apart from this no difference compared to healthy fertile women. These changes were detectable using continuous registration which stresses the value of such measurements in the investigation of urinary incontinence.