The effect of vesical filling and voiding on the anorectal function with evidence of a 'vesico-anorectal reflex'.
The aim was to evaluate the effect of vesical filling and voiding on anal continence and rectal pressure. Fourteen healthy volunteers (age 37.2 +/- 9.6 years; 10 men, four women) were studied. The response of the rectal pressure and EMG of the external (EAS) and internal (IAS) anal sphincters to slow vesical filling and voiding was recorded before and after individual anaesthetization by xylocaine of the EAS, rectum and urinary bladder. Saline instead of xylocaine was used as control testing. The rectal pressure and EAS EMG activity showed no response to vesical filling (P > 0.05, P > 0.05, respectively) while a momentary increase in both parameters occurred upon voiding (P < 0.05, P < 0.01, respectively). The IAS EMG exhibited no response to either filling or voiding. Separate anaesthetization of either of the EAS, rectum or bladder produced no response of the rectal pressure or EAS EMG activity upon vesical voiding, whereas a response was registered after saline administration. The increase of the rectal pressure and EAS EMG activity upon voiding suggests the presence of a reflex relationship between the two actions. This relationship is evidenced by reproducibility and by abolition of the response on anaesthetizing either of the proposed two arms of the reflex: the anorectum and the bladder. We call this reflex 'vesico-anorectal reflex'. The clinical significance of this vesico-anorectal reflex remains to be established.
D000328:Adult; D001003:Anal Canal / Q000502:physiology*; D003672:Defecation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012007:Rectum / Q000502:physiology*; D012016:Reference Values; D012018:Reflex / Q000502:physiology*; D001743:Urinary Bladder / Q000502:physiology*; D014554:Urination