PURPOSE:Functional derangement in bowel movement after ileal pouch-anal anastomosis (IPAA) is not infrequent. It results from several mechanisms mainly decreased rectal reservoir capacity and rectal sensation. Anal sphincter or pelvic nerve damage during surgery contributes physiological changes, also. This study was performed to evaluate manometric changes after IPAA and compare them with functional outcomes regarding anastomotic technique. METHODS:Forty seven (M:F=23:24) patients who underwent IPAA and manometric assessment were enrolled. Pathological diagnoses of them were 32 ulcerative colitis, 12 familial adenomatous polyposis, and 3 hereditary non-polyposis colorectal cancer. Every pouch was constructed in J shape, 15cm length. Pouch-anal anastomosis was performed by 27 hand-sewn and 20 double stapling technique. Diverting ileostomy was performed in 30 cases (64%) and closed 2-3 months after IPAA. Manometry was performed preoperatively and 3 to 6 months interval, postoperatively. Twenty two patients underwent full manometic assessment pre- and post-operatively. The others did it either pre or postsoperatively. Functional outcome was investigated at the median follow-up period 25 (2-54) months. Statistical analysis was performed by using Chi- square and Fisher's exact test. Significance was assigned to a P value of <0.05. RESULTS:Maximum resting pressure (MRP) was significantly decreased postoperatively (85.2 vs. 60.6 mmHg; P=0.002). This phenomenon could be observed throughout the follow-up period. However, the difference was getting smaller as times went by. Rectoanal inhibitory reflex (RAIR) was identified 96% preoperatively, and only 22% postoperatively (P=0.000). Rectal compliance was decreased at the time of ileostomy closure, and improved remarkably since 6 months after closure. In comparison of manometric findings according to anastomotic technique, MRP in hand- sewn group was significantly decreased (52.3 vs. 77.0 mmHg; P=0.003). RAIR could be identified more frequently in double stapled group (31.6 vs. 15.4%; P>0.05). Postoperative stool frequency and incontinence rate were not different between two groups. Thirty one percent of patients revealed night time seepage. MRP of this seepage group was significantly lower than the other group (67.9 vs. 48.4 mmHg; P=0.038). CONCLUSIONS:Characteristic changes of manometric findings after IPAA were summarized as decrease of MRP and disappearance of RAIR. Rectal compliance was significantly improved since 6 months after IPAA or ileostomy closure. Decrease of MRP was more remarkable in hand-sewn group. However, we could not find any difference in functional outcomes between two anastomotic techniques. MRP was a crutial factor for postoperative seepage.