Key factors influencing bowel function after ileal W-pouch anal anastomosis: a spectral analysis of W-pouch motor activity.

Restorative proctocolectomy with ileal pouch anal anastomosis (IPAA) has become the standard surgical procedure for ulcerative colitis (UC). The purpose of this study was to determine which factors are important to achieve good anal continence after IPAA in terms of the motor activity and pressure-volume relationship. A total of 17 patients with UC who underwent IPAA were evaluated. The internal ileal pouch pressure was transanally measured with and without volume-loading of the pouch which induces the urge to evacuate. The maximum tolerable volume (MTV), first urge volume (FUV), and ileal pouch compliance were calculated and the internal ileal pouch pressure records were subjected to spectral analysis for intensive evaluation of the intraluminal pressure waves. The FUV, correlation of the compliance of the FUV with MTV, and the remaining volume up to the MTV (RVMTV) were analyzed. Compliance of the FUV was significantly correlated with the RVMTV (r = 0.736, P < 0.01). The frequency of the phasic waves in the pouch decreased with length of follow up, reflecting improved function (r = -0.588, P < 0.05). The findings of this intensive analysis of manometric measurement indicate that the key factors in postoperative pouch function are RVMTV and the frequency of phasic waves in the W-pouch.