Anorectal function following colo-anal sleeve anastomosis for chronic radiation injury to the rectum.

Anorectal manometry and electrophysiological studies of the pelvic floor were performed in eight patients who had undergone anterior resection of the rectum with mucosal proctectomy and colo-anal sleeve anastomosis for radiation rectal injury. There is a severe reduction in the compliance of the neorectum and in the maximal tolerable volume. Maximum basal anal canal pressure and physiological sphincter length are also significantly reduced although the 'squeeze' pressure of the external anal sphincter and the latency of the pudendo-anal reflex were unaffected. Four patients had an absent rectosphincteric reflex, four patients involuntarily expelled the test balloon at the maximal tolerable volume during a proctometrogram and four patients demonstrated increased EMG activity of the pelvic floor on straining and on rectal distension. These abnormalities help to explain many of the patients' symptoms. Histological abnormalities of the myenteric plexus were a prominent feature in all the excised specimens and may be responsible for some of the functional abnormalities.