Physiological assessment of the function of the ileocecal junction with evidence of ileocecal junction reflexes

Abstract

Background: The ileocecal junction (ICJ) appears to be a specialized segment of the gut which regulates the passage of the chyme from the ileum to the cecum. We investigated the response of the ICJ to cecal and ileal distension and the nature of this response (direct or reflex).

Material/methods: Nine patients who had early cancer in the proximal transverse colon were studied during right hemicolectomy. The pressure response of the ICJ to cecal and ileal balloon distension was determined before and after cecal and ileal anesthesia. The balloon and manometric catheters were introduced into the cecum and ileum by colotomy and ileotomy, respectively. ICJ length was measured by the pull-through technique.

Results: The ICJ high pressure zone had a mean length of 3.6 cm. Chyme flow to the cecum occurred in jets. Large-volume cecal distension caused a significant rise in cecal and ICJ pressures and decreased ileal pressure; the balloon was dispelled to the transverse colon. Large-volume ileal distension caused an increase in ileal pressure, decreased ICJ and cecal pressures, and aboral balloon movement. No pressure response was produced by small volume distension or anesthesia of the cecum or ileum.

Conclusions: Ileal distension is suggested to initiate reflex ICJ and cecal relaxation which is mediated through the 'ileocecal inhibitory reflex' and which allows the chime to pass to the cecum. Cecal distension appears to evoke reflex ileal and ICJ contraction, thus preventing ceco-ileal reflux and allowing time for chyme to accumulate in, and distend, the terminal ileum; we call this reflex the 'ceco-ileal excitatory reflex'. These 2 reflexes are thought to regulate chyme passage through the ICJ.