Functional activity of the rectum: A conduit organ or a storage organ or both?
OBJECTIVE
To investigate whether the degree of rectal distension could define the rectum functions as a conduit or reservoir.


METHODS
Response of the rectal and anal pressure to 2 types of rectal balloon distension, rapid voluminous and slow gradual distention, was recorded in 21 healthy volunteers (12 men, 9 women, age 41.7 +/- 10.6 years). The test was repeated with sphincteric squeeze on urgent sensation.


RESULTS
Rapid voluminous rectal distension resulted in a significant rectal pressure increase (P < 0.001), an anal pressure decline (P < 0.05) and balloon expulsion. The subjects felt urgent sensation but did not feel the 1st rectal sensation. On urgent sensation, anal squeeze caused a significant rectal pressure decrease (P < 0.001) and urgency disappearance. Slow incremental rectal filling drew a rectometrogram with a "tone" limb representing a gradual rectal pressure increase during rectal filling, and an "evacuation limb" representing a sharp pressure increase during balloon expulsion. The curve recorded both the 1st rectal sensation and the urgent sensation.


CONCLUSIONS
The rectum has apparently two functions: transportation (conduit) and storage, both depending on the degree of rectal filling. If the fecal material received by the rectum is small, it is stored in the rectum until a big volume is reached that can affect a degree of rectal distension sufficient to initiate the defecation reflex. Large volume rectal distension evokes directly the rectoanal inhibitory reflex with a resulting defecation.
Shafik
Ahmed
A
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt. shafik@ahmedshafik.com
Mostafa
Randa M
RM
Shafik
Ismail
I
Ei-Sibai
Olfat
O
Shafik
Ali A
AA
D000328:Adult; D001003:Anal Canal / Q000502:physiology; D002404:Catheterization; D003248:Constipation / Q000503:physiopathology; D003672:Defecation / Q000502:physiology*; D005243:Feces; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012007:Rectum / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D012812:Sigmoidoscopy