Abstracts
1999 Digestive Disease Week

# 2089 TOPOGRAPHICAL VARIABILITY IN SUSCEPTIBILITY TO INFLAMMATION IN THE ILEOANAL PULL-THROUGH POUCH
C M Schmidt, Johns Hopkins Med Inst, Baltimore, MD; A J Lazenby, E Abernathy, R J Hendrickson, C A Capadonna, J V Sitzmann, Georgetown Univ Med Ctr, Washington, DC

Pouchitis is the most frequent complication of transanal continent reservoirs in patients after ileoanal pull-through (IAPT) procedure. We conducted pouch biopsies on 73 patients with inflammatory bowel disease or familial adenomatous polyposis who underwent IAPT by a single surgeon over a 10 year time period. A pathologist in blinded fashion has graded 468 IAPT pouch biopsies and 67 of the patient's pre-operative terminal ileal resection histopathology. We hypothesized that topographical variability in susceptibility to inflammation exists within the IAPT ''J'' pouch. Topographical analysis of inflammation within the IAPT pouch was performed by taking biopsies from the inlet, apex, middle and base of IAPT pouches. IAPT pouch histopathology was also compared with the histopathology of pre-operative terminal ileal resection specimens. Terminal ileum and IAPT pouch histopathology were graded by active inflammation, chronic inflammation, lymphocyte aggregates, intraepithelial lymphocytes, eosinophils and villous blunting. There is a significant increase in the degree of active and chronic inflammation in the IAPT pouch versus the pre-operative terminal ileal resection [Mann Whitney Rank Sum (MW), p=0.001]. There is also a significant increase in the degree of villous blunting in the IAPT pouch versus the preoperative terminal ileal resection (MW, p=0.001). Conversely, there is a significant decrease in the degree of lymphoid aggregates in the IAPT pouch versus the pre-operative terminal ileal resection (MW, p=0.001). There is, however, a significant increase in the number of eosinophils and intraepithelial lymphocytes in the IAPT pouch versus the pre-operative terminal ileal resection [t-test, p=0.0002 (95% CI: 20.1, 34.9) and p=0.01 (95% CI: 1.88, 8.12) respectively]. Within the IAPT pouch tere is a significant linear gradient of increasing active inflammation from inlet to base (R2=90%, p=0.05). There is also a significant linear gradient of increasing villous blunting from the inlet to base of the IAPT pouch (R2=93%, p=0.03). There is a trend towards a linear gradient of increasing eosinophils and intraepithelial lymphocytes from the inlet to base of the IAPT pouch (R2=83%, p=0.09 and R2=79%, p=0.11). There is a significant increase in the degree of inflammation in the IAPT pouch versus the pre-operative terminal ileal resection. There is a gradient of increasing susceptibility to pouch inflammation from the inlet to the base of the IAPT pouch. This suggests that the environment of the neorectum from inlet to base exerts an increasing gradient stimulus to inflammation which appears to override any influence of ileal tissue proximity to the colon.

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