Decrease in the anorectal pressure gradient after low anterior resection of the rectum

Abstract

Changes in anorectal function after low anterior resection of the rectum (LAR) often lead to symptoms of urgency and frequency of defecation, the anterior resection syndrome. It has been reported that preservation of part of the rectum improves clinical results, but why this should be remains unclear. We have carried out continuous ambulatory manometric studies in two groups of patients: 11 patients, a median of 11 (range, 5-96) months after LAR, in whom the median anastomotic level above the anal high-pressure zone was 0 (range, 0-2) cm; 9 patients, a median of 6 (range, 3-12) months after sigmoid colectomy, in whom the rectum remained in situ and who acted as controls. Comparing the LAR group with controls, resting anal pressures were lower, median 68 (range 27-102) cm H2O vs. 95 (45-116) cm H2O (PCONCLUSIONS: The inferior clinical results observed after LAR compared with the results after sigmoid colectomy are thus in part because of higher neorectal pressure acting on a weakened sphincter mechanism. These observations lend support to the idea that neorectal capacity should be increased in patients who undergo low anterior resection.