Bile acid absorption after near-total proctocolectomy in dogs: Ileal pouchvs. jejunal pouch-distal rectal anastomosis

Bile acid malabsorption is often present in patients after near-total proct ocolectomy and ileal pouch-anal canal anastomosis, suggesting ileal dysfunc tion. Experiments were performed in dogs to compare bile acid absorption af ter a modified procedure, in which a jejunal pouch was interposed between t he terminal ileum and the distal rectum, with that after a conventional ile al pouch operation. Fecal bile acid output (equivalent to hepatic bile acid biosynthesis) and composition were determined by gas chromatography/mass s pectrometry in five jejunal pouch dogs and in five ileal pouch dogs more kh an 6 months after operation. Fecal bile acid output in the jejunal pouch do gs (mean +/- standard deviation) was 215 +/- 59 mg/day (10.1 +/- 2.7 mg/kg- day), a value similar to that obtained in the ileal pouch dogs (261 +/- 46 mg/day [12.8 +/- 3.1 mg/kg-day]; P > 0.05). These values were also similar to those reported by others for healthy unoperated dogs, indicating that in creased bile acid biosynthesis occurring in response to bile acid malabsorp tion was not present. Fecal bile acids in pouch dogs were completely deconj ugated and extensively 7-dehydroxylated (jejunal pouch = 90.4% +/- 3.9% deh ydroxylated; ileal pouch = 88.6% +/- 6.6% dehydroxylated) and consisted pre dominantly of deoxycholic acid derivatives. We conclude that when either a jejunal pouch or an ileal pouch is used as a rectal substitute in dogs, an anaerobic pouch flora develops that efficiently deconjugates and dehydroxyl ates bile acids, rendering them membrane permeable. The resultant passive a bsorption of unconjugated bile acids appears to compensate for any loss of active ileal absorption of conjugated bile acids, and bile acid malabsorpti on does not occur.