A comparison of J and W pouches using an isolated ileal reservoir in pigs

A new model for studying ileal reservoirs was used to compare J and W pouches. Sixteen female piglets were operated on between 62 and 67 days of age (median = 65). An approximately 50 cm vascularized segment of terminal ileum was isolated from the faecal stream and intestinal continuity restored. The distal 40 cm of the isolated loop was opened along its antimesenteric border and the pouch constructed (J = 8, W = 8). The remaining proximal length of ileum was brought out through the abdominal wall as a mucous fistula. One piglet in the W pouch group died post-operatively and in another, spontaneous closure of the mucous fistula prevented access to the W pouch for testing leaving six W and eight J pouches for comparison. Compliance was tested at 4 weeks by measuring intrapouch pressure during continuous distension by water. The volumes instilled at pressures of 20, 40, 60 and 80 cm of water were compared using the Mann-Whitney U-Test. Volumes varied widely at all pressures within both study groups although W pouches tended to be of larger volume for any given pouch pressure (P = NS). The failure of this study to demonstrate more clearly a difference between J and W pouches may be due to the small numbers involved but the wide range of volumes seen raises doubts about the usefulness of this pouch model.