Tierexperimentelle Untersuchungen zum Entleerungsverhalten ileoanaler Pouches
Proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the method of choice in the surgical therapy of ulcerative colitis or adenomatous polyposis. While the reservoir function of the pouch is undoubted, the role of its motility during defecation is still speculative.
IPAA was performed in 12 dogs and pouch motility was recorded directly by serosal strain gauges and electromyography 12–15 weeks postoperatively. Defecation mechanisms were evaluated by motility recordings during inflation and defecation of a endoluminal balloon and by additional defecography with sequential sector-related grey scale analysis.
Stool frequency increased from 2 ±1 to 14±3 stools/d. Pouch compliance was significantly lower than rectal compliance (2,8 ± 0,5 vs. 4,5 ± 0,7 ml/mmHg). Spontaneous defecations appeared in 30 cases without significant changes of electrical or mechanical activity of the pouch. Sequential filling of the pouch led to defecation in only 4 dogs, while the others did not succeed in emptying their pouch even with maximal balloon inflation. Neither strain gauge measurements nor electromyography demonstrated significant contractions of the pouch during defecation, while sector-related grey scale analysis revealed strong contractions of the abdominal wall during pouch emptying.
Therefore, we conclude that pouch emptying is independent from intrinsic pouch motility. The ileoanal pouch acts as a functionally passive reservoir and its evacuation is initiated by a Valsalva-like manoeuvre with rise of the intra-abdominal pressure due to contractions of the abdominal wall.
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