Study of the motile activity of the colon in rectal inertia constipation

We have recently demonstrated that rectal distension effected left colonic contraction, which probably acts to feed the rectum with fecal matter each time the rectum distends and evacuates its contents. This effect was postulated to occur through the recto-colic reflex. As the colonic status in rectal inertia constipation was scarcely addressed in the literature, we investigated this point.

The response of the colonic pressure to rectal balloon distension in increments of 10 mL of water was studied in 38 patients with rectal inertia constipation (IC) (age 42.6 +/- 14.3 years, 29 women) and 12 healthy volunteers (40.9 +/- 12.2 years, nine women). The rectal and colonic pressures were measured by saline-perfused tubes connected to a pneumohydraulic infusion system. The rectum was distended by a condom applied to the end of a 10-F catheter.

The rectal and left colonic resting pressures were significantly lower in the patients than in the controls (P < 0.5, P < 0.05, respectively). In the healthy volunteers, rectal distension up to first rectal sensation produced no significant rectal or colonic pressure changes (P > 0.05, P > 0.05). At urge, rectal and left colonic pressures increased significantly (P < 0.001, P < 0.001, respectively), but there were no changes in the right colonic pressure (P > 0.05). The colonic response lasted as long as the rectum was distended. In IC, patients did not perceive the first rectal or urge sensation up to a rectal balloon filling of 300 mL; there was no rectal or colonic pressure response (P > 0.05, P > 0.05).

In normal subjects, left colonic contraction on rectal distension probably acts to feed the rectum with fecal material. In IC, the low left colonic resting pressure assumedly points to left colonic hypotonia which appears to aggravate the constipation produced by the inertic rectum. Furthermore, non-response of the left colon to rectal distension probably impedes rectal feeding with fecal matter and enhances constipation.