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Colonic intraluminal pressure and intestinal transit were examined in diverticular disease, idiopathic constipation, and the irritable colon syndrome. Small bowel transit was normal. Total gastrointestinal transit was prolonged. Colonic transit showed an equal delay in all segments, expedited by bran. In constipation, transit was the more prolonged, but in the irritable colon syndrome, pressure was more affected. Diverticular disease patients showed features resembling each of these two groups. Pressure and transit showed an inverse relationship maintained after bran.

Minor difficulties with continence may occur after low anterior resection. Intraoperative injury to the internal anal sphincter or its nerve supply may contribute to this. To study the effect of low anterior resection on the anal sphincter mechanism, anal manometry was performed on 20 patients before and 10 days after resection. Fifteen patients were studied again 6 months after operation. Resting, maximum squeeze and squeeze increment pressures were recorded. Intraoperative manometry (n = 11) and presacral nerve stimulation (n = 6) were performed to determine whether peroperative injury to the internal anal sphincter had occurred. Resting and maximum squeeze anal canal pressures were reduced by low anterior resection, and did not recover. The squeeze pressure increment did not change. Division of the inferior mesenteric artery, full mobilization of the rectum and mesorectum, and rectal transection did not affect resting anal pressure, which was reduced after EEA anastomosis (mean (s.e.m.) before, 40(5) mmHg; after, 27(4) mmHg; P less than 0.05, n = 5). Presacral nerve stimulation produced relaxation of the internal sphincter. Anal sphincter pressures are reduced after low anterior resection. The external anal sphincter and the nerve supply to the internal anal sphincter appear intact. A direct injury to the internal sphincter is postulated.

Colonic motor activity and serum gastrin levels were correlated during a basal period and after a meal in 16 subjects. Motor activity preceded the gastrin response. The motility index and the serum gastrin levels rose in parallel, but the motility fell before later showing a second rise. The frequency response showed the earliest change and since it preceded the gastrin rise may be neurogenic. This response was later "extinguished" and replaced by one of waves of increasing amplitude; the sustained nature of this response fitted more closely the gastrin response.