Recto-colic reflex: role in the defecation mechanism.

As urge is felt and defecation starts, it is postulated that the colon continuously feeds the rectum with stools until the colon is empty. The relationship of rectal distension at defecation to colonic activity is not yet fully explored. The current communication studies this relationship in 11 patients (mean age 48.4+/-18.8 years, 6 men and 5 women) with transverse colostomy performed after transverse colectomy for cancer of the transverse colon. The rectum was distended by a condom-ended catheter in increments of 10 ml of H20, and the pressures in the right and left colon were measured by balloon catheters introduced through the colostomy. The test was repeated after anesthetizing the rectum or colon, respectively. Upon rectal distension up to sensation of urge, there was no colonic pressure response. At urge (mean distension volume of 160+/-36.7 ml), the left colonic pressure showed a significant rise (p<0.001), while the right colon revealed no response (p>0.05). Rectal distension during rectal or colonic anesthetization effected no colonic pressure response (p>0.05). The left colonic contraction upon rectal distension, being reproducible and absent with the anesthetized rectum or colon, postulates a reflex relationship which we call "recto-colic reflex". This reflex acts at defecation to feed the rectum successively with fecal material until the colon is emptied. Reflex derangement may play a role in defecation disorders.