Stanford University School of Medicine, USA
Chris Constantinou investigated the function and structure of the urinary tract in Urology at Stanford University for over 40 years. His basic interests has always been in clinical and basic investigations of urinary continence and the impact of surgical and pharmacological procedures in their treatment. His current specific interest is based on the application of new technological in evaluating urethral, bladder and pelvic floor function. He maintains a close collaboration with departments of gynecology, biomedical engineering and experimental surgery. He is on the editorial board of many journals and the Editor in Chief of the Open Journal of Obstetrics and Gynecology.
The anatomical organization and the physiological characteristics of the urethra together with the associated pelvic floor attachments are the main contributory functional aspects of urinary continence. Anatomically, the female urethra contains passive smooth muscle components and a skeletal sphincter, which controls the reflex activity to stress. Measures of urethral function are the Resting Urethral Pressure Profile (RUPP) that determines primarily the Max. Urethral Closure Pressure (MUCP) and the Stress Transmission Pressures ratio (STP) contributed by the abdominal contents acting upon the urethra. In young women MUCP values are in the order of 150 cm H2O and STP values are amplified to about 1.6 times the abdominal pressures. Further more the timing of the response of urethral closure is such that it precedes the stress by 250 ms suggesting that urethral function is aided by a fast reflex response. With aging MUCP decreases slowly to 30 cm H2O at the age of 70 and the STP to 1.1 times. With decreasing urethral pressure the max voiding pressure also decreases, an indication of loss of urethral resistance. Following surgical procedures to correct stress urinary incontinence, MUCP does not significantly increase, suggesting that there is no impact on the urethra, but STP is restored to values approaching those of normal young women. Observations suggest that surgical correction influences the effect of abdominal pressure transmission on urethral function presumably by the relocation of the urethra within the sphere of influence of the pelvic floor muscles and their response to stress.