Comparison of different J-pouches vs. straight and side-to-end coloanal anastomoses: experimental study in pigs

Functional results after low anterior resection with straight coloanal anastomosis are poor. Although certain functional aspects are improved with coloanal J-pouch anastomosis, evacuation difficulties are encountered in some of these patients. The aim of the study was to investigate the functional results of different reconstruction methods after low anterior resection in a standardized pig model.

Thirty-two adult Göttinger mini pigs were randomly assigned either to straight end-to-end (Group 1), side-to-end (Group 2), small (4-cm limb length) J-pouch (Group 3), or large (8-cm limb length) J-pouch (Group 4) coloanal anastomosis after low rectal excision. The animals were investigated 12 weeks after the operation by measuring neorectal compliance and ceruletide-induced defecation. Eight pigs without operation were used as controls (Group 5).

Compliance was lowest in Groups 1 and 2, which were significantly different compared with both pouch designs and controls. Neorectal compliance of pigs with either small or large pouches did not differ significantly compared with one another or controls. Defecation was significantly impaired in pigs with a large pouch compared with all other groups. Pigs with side-to-end anastomoses had as rapid an evacuation as animals with straight coloanal reconstruction.

Coloanal J-pouch reconstruction adequately restores reservoir capacity after low anterior resection of the rectum. From a functional point of view, side-to-end is not superior to straight coloanal anastomosis. Compared with small pouches, a large pouch design does not lead to better neorectal compliance in the pig model, whereas pouch evacuation seems to be considerably compromised.