The electromyographic activity of the external and internal urethral sphincters and urinary bladder on vaginal distension and its role in preventing vaginal soiling with urine during sexual intercourse.
OBJECTIVE
We investigated the hypothesis that external (EUS) and internal (IUS) urethral sphincters and urinary bladder (UB) respond to penile thrusting (PT) of vagina in a way that prevents urinary leakage during coitus.


METHODS
Vaginal condom was inflated with air in increments of 50-300 ml and EMG of EUS and IUS and vaginal pressure were recorded; test was repeated after anesthetization of vagina, UB, EUS, and IUS.


RESULTS
Vaginal distension effected reduction of vesical pressure but increase of IUS EMG until the 150 ml distension was reached, beyond which more vaginal distension caused no further effect; EUS EMG showed no response. Vaginal distension while vagina, UB, EUS, and IUS had been separately anesthetized, produced no change.


CONCLUSIONS
Vaginal balloon distension appears to effect vesical relaxation and increased IUS tone. This seems to provide a mechanism to avoid urine leakage during coitus and to occur through a reflex we term 'vagino-urethrovesical reflex'.
Shafik
Ahmed
A
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt. shafik@ahmedshafik.com
Shafik
Ali A
AA
Shafik
Ismail A
IA
El Sibai
Olfat
O
D000328:Adult; D003075:Coitus / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009130:Muscle, Smooth / Q000502:physiology; D011312:Pressure; D012018:Reflex / Q000502:physiology; D014521:Urethra / Q000502:physiology*; D001743:Urinary Bladder / Q000502:physiology*; D014549:Urinary Incontinence / Q000503:physiopathology*; D014621:Vagina / Q000502:physiology*