Variations in urethral and bladder pressure during stress episodes in healthy women.

Pressure variations in the urethra and bladder during stress episodes and their time separations were investigated in 30 healthy female volunteers. The pressure was measured by means of a double microtip transducer catheter with the distal sensor in the bladder and the proximal sensor at the bladder neck, the mid-urethra and the distal urethra. In advance of the pressure spike during cough a pressure rise was demonstrated in the bladder and at all 3 sites of measurement in the urethra. The urethral pressure increments preceding and following the pressure spike were statistically significantly higher in the mid-urethra than the corresponding bladder pressures. This active urethral pressure generation in the mid-urethra and distal urethra was initiated 200 ms before the bladder pressure began to rise. The pressure in the urethral high pressure zone was higher than the bladder pressure in all cases. Passive pressure transmission to the urethral high pressure zone can take place only insignificantly due to a continuous higher pressure inside the urethra than in the bladder and due to the location of the high pressure zone in the demarcation of the abdominal cavity. It was concluded that the urethral pressure rise in the high pressure zone during stress episodes is mainly generated actively by intra- and/or peri-urethral structures.