Changes in Anal Pressures and Function after Low Anterior Resection

In this study we evaluated changes in anal function and pressures in 16 patients undergoing low anterior resection for a rectal neoplasm. After a significant initial decrease in resting anal (37%) and maximal squeeze pressure (31 %), anal function improved and after 1 year was 86 and 95% of the respective preoperative values (p NS). Defecation frequency (mean ± SD) was significantly higher after 1 year than preoperatively, 3.9 ± 2.2 versus 2.7 ± 2.2 times a day (p = 0.049). In 3 of 9 previously continent patients continence became worse, 1 patient suffering from frequent major soiling. Four of seven patients with minor continence problems regained normal continence. On the whole, the patients’ continence before and after operation was similar. Postoperative continence was not related to anal pressures in the preoperative manometry. However, in 3 patients with worse postoperative continence, anal pressures were normal. In 6 patients with a clinical anastomotic leakage maximal squeeze pressure at the end of follow-up was significantly lower than before operation, but anastomotic leakage had no effect on the patients’ postoperative continence. In conclusion, the study demonstrates a slight decrease in anal pressures which seems not to affect the patients’ postoperative continence. Patients with worse postoperative continence had normal anal pressures and more than half the patients with minor continence problems regained normal continence. Therefore patients should not be denied a low anterior resection if anal pressures are low and/or minor continence problems exist.