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

Background/Aims: To study the effect of rectal distension on jejunal and il eal motility aiming at the assessment of the possible role of rectal disten sion induced by constipation on the transport of the material in the gut. Methodology: The rectum of 16 healthy volunteers (mean age: 38.6+/-11.7 yea rs, 10 men, and 6 women) was distended by a balloon filled with water in in crements of 50mL up to 200mL and the response of the jejunal and ileal pres sures was recorded. The test was repeated distending the anesthetized rectu m 20min and 3 hours after anesthetization. Results: Rectal distension with 50mL 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 200mL cau sed jejunal and ileal pressure response similar to that of the 100mL disten sion (P>0.05). Distension of the anesthetized rectum effected no significan t jejunal or ileal pressure changes. Conclusions: The results were reproducible in the individual subject. The d ecline of the intestinal pressure upon rectal distension postulates a refle x relationship between the 2 conditions. This reflex nature is evidenced by reproducibility and by its absence on distension of the anesthetized rectu m. 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 h ypotonia, a hypothesis which requires further studies.