Coloanal anastomosis: are functional results better with a pouch?

Different studies have shown that low colorectal and coloanal anastomosis often yield poor functional results. The aim of the present study was to investigate whether a colonic reservoir is able to improve functional results.

Thirty-eight consecutive patients subjected to low anterior resection were randomized following rectal excision in two groups. One (n = 19) had a stapled straight coloanal anastomosis, and the other (n = 19) had a 10-cm stapled colonic pouch low rectal anastomosis. Median anastomotic distance above the anal verge was 3.38 +/- 0.56 cm and 2.14 +/- 0.36 cm in both groups, respectively. Continence alterations, urgency, tenesmus, defecatory frequency, anal resting and maximum voluntary squeezing pressures, and maximum tolerable volume were evaluated one year later.

One patient died of pulmonary embolism, and seven presented with a recurrence and were excluded from the study. Stool frequency was greater than three movements per day in 33.3 percent of cases with a reservoir and in 73.3 percent of those with a straight coloanal anastomosis (P < 0.05). Maximum tolerable volume was significantly greater in patients with a reservoir (335 +/- 195) than in those without (148 +/- 38) (P < 0.05). There were no significant differences in other variables studied.

This study shows that some aspects of defecatory function after rectal excision could improve with a colonic reservoir.