Comparative intrinsic and extrinsic compliance characteristics of S, J, and W ileoanal pouches

Although compliance of the ileoanal reservoir pouch has been shown to affect function, previous compliance studies may have been influenced by the compliance of the small bowel proximal to the pouch and by supporting pelvic structures. The following study was designed to isolate the pouch and to compare intrinsic and extrinsic factors influencing pouch compliance. Thirty-three mongrel dogs underwent rectal mucosectomy and protocolectomy with S-pouch (S) in nine, stapled J-pouch (SJ) in nine, handsewn J-pouch (HJ) in nine and handsewn W-pouch (SW) in six. At 2 weeks, each dog underwent laparotomy, the small bowel 2 cm proximal to the pouch was clamped, and in vivo pouch compliance was measured using anal balloon occlusion and continuous saline infusion manometry. The pouch was then removed and ex vivo measurements were repeated. Mean compliance slopes between 0 and 40 cm H₂O were compared by ANOVA and paired t-ests. In vivo and ex vivo compliance in ml/cm H₂O was 3.1±1.2 and 3.8±1.6 (P=0.25) for the S-pouch, 3.1±0.6 and 5.2±1.7 (P<0.01) for the SJ-pouch, 2.3±0.5 and 4.8±0.7 (P<0.001) for the HJ-pouch, 3.6±0.6 and 6.0±0.7 (P<0.001) for the W-pouch. Pearson's correlation coefficient for in vivo and ex vivo measurements of the S, SJ, HJ, and W pouches were r²=0.066, 0.001, 0.039, and 0.379, respectively. It is concluded that: 1) Isolated pouch compliance can be accurately measured in experimental animals with proximal and distal occlusion and inflow manometry. 2)In vivo compliance is significantly less in the HJ compared with S, SJ, and W pouches. 3) Differences between in vivo and ex vivo compliance of SJ, HJ, and SW pouches are significant. 4)In vivo and ex vivo compliance determinations correlate poorly. 5) Extrinsic factors contribute significantly to pouch compliance.