Reasons for failure to construct the colonic U-pouch. What can be done to improve the size of the neorectal reservoir should it occur?

PURPOSE: The aim of this study was to determine first, the reasons for failure to construct a neorectal reservoir after anterior resection and coloanal anastomosis for rectal adenocarcinoma and the rate at which it occurred and second, to determine whether the adoption of a new coloplasty pouchanal anastomosis improved this failure rate. METHODS: From the colorectal cancer database of a single institution, a single surgeon's patients who underwent resection and coloanal anastomosis from March 1990 to June 1999 were identified. After thorough chart review those patients who underwent straight coloanal anastomosis, J-pouch-anal anastomosis, and coloplasty pouch-anal anastomosis could be identified. In each case of straight coloanal anastomosis, the cause of the failure to create a neorectal reservoir was sought. The study group was further subdivided into those who had their operation either before or after the introduction of the coloplasty pouchanal anastomosis. RESULTS: Of 107 patients who fitted the criteria for study, 66 (61.7 percent) had a J-pouch-anal anastomosis, and 13 (12.1 percent) had a coloplasty, pouch-anal anastomosis. Twenty-eight patients had a straight coloanal anastomosis when a neorectal reservoir could not be constructed, an overall failure rate of 26.2 percent for the total period of study. Seven reasons were identified for this failure, of which there were a total of 31 episodes. These reasons were 1) technical (narrow pelvis, bulky anal sphincters or need for mucosectomy, diverticulosis, insufficient colon length or pregnancy) 2) nontechnical (complex surgery or distant metastases present). Failure to construct a neorectal reservoir for the period of study before the introduction of coloplasty pouch-anal anastomosis occurred in 27 of 88 (30.7 percent) patients. This was reduced to 1 of 19 (5.3 percent) patients in the later period of study, a significant improvement (P = 0.022) CONCLUSIONS: Seven factors have been identified which may result in the failure to construct a neorectal reservoir after rectal resection and coloanal anastomosis. This may occur in a sizable minority of patients. The introduction of coloplasty pouch-anal anastomosis has resulted in a significant improvement in this failure rate.