Pressure and prolapse--the cause of solitary rectal ulceration.

The cause of solitary rectal ulceration has been investigated using a method that radiologically visualises rectal voiding whilst simultaneously measuring intrarectal pressure and external anal sphincter electromyographic activity. Control subjects and patients with the solitary rectal ulcer syndrome, both with and without mucosal ulceration, have been studied. A high incidence of rectal prolapse (94%) was present in the patients who voided. Overactivity of the anal sphincter during evacuation contributed to the fact that patients with mucosal ulceration required higher intrarectal pressures to void than the controls and the patients without mucosal ulceration. The results indicate that a combination of rectal prolapse and a high voiding pressure may act to cause the mucosal ulceration in this syndrome by exposing the rectal wall to a high transmural pressure gradient.