Manometric analysis of anal sphincter damage after ileal pouch-anal anastomosis

A constant reduction in anal sphincter pressure follows an ileoanal pouch procedure for ulcerative colitis and familiar adenomatous polyposis. We analyzed whether this reduction is more likely due to neurogenic damage or to direct sphincter trauma. Three-dimensional vector volume manometry was performed in 75 patients prior to the ileoanal pouch procedure and 3 months thereafter. Resting pressure was significantly reduced from 83.5 +/- 24.4 to 58.1 +/- 18.0 mmHg and squeezing pressure from 204.7 +/- 63.3 to 173.4 +/- 50.6 mmHg. Moreover, significant vector volume reductions were recorded postoperatively, and the asymmetry index increased significantly (resting: 11.5 +/- 4.1% to 18.4 +/- 7.4%; squeezing: 9.6 +/- 3.1 to 13.0 +/- 6.7%). Functional anal sphincter length at the high-pressure zone remained unchanged. Thus, there was no local damage to proximal or distal anal sphincter segments, which suggests that the postoperative impairment of sphincter function is secondary to neurogenic rather than morphological damage.