Effect of rectal distension on the small intestine with evidence of a recto-enteric reflex

To study the effect of rectal distension on jejunal and ileal motility aiming at the assessment of the possible role of rectal distension induced by constipation on the transport of the material in the gut.

The rectum of 16 healthy volunteers (mean age: 38.6 +/- 11.7 years, 10 men, and 6 women) was distended by a balloon filled with water in increments of 50 mL up to 200 mL and the response of the jejunal and ileal pressures was recorded. The test was repeated distending the anesthetized rectum 20 min and 3 hours after anesthetization.

Rectal distension with 50 mL of water effected no jejunal or ileal pressure changes (P > 0.05). One hundred-mililitre (100-mL) rectal distension produced decrease of jejunal and ileal pressures (P < 0.05) which lasted as long as distension was maintained. Rectal distension with 150 and 200 mL caused jejunal and ileal pressure response similar to that of the 100 mL distension (P > 0.05). Distension of the anesthetized rectum effected no significant jejunal or ileal pressure changes.

The results were reproducible in the individual subject. The decline of the intestinal pressure upon rectal distension postulates a reflex relationship between the 2 conditions. This reflex nature is evidenced by reproducibility and by its absence on distension of the anesthetized rectum. We termed this reflex relation: "recto-enteric reflex". It is suggested that under normal physiologic conditions the reflex inhibits the intestinal transit, thus giving the rectum time to evacuate itself. Continuous rectal distension, as occurs in inertia constipation, appears to effect enteric hypotonia, a hypothesis which requires further studies.