Pouchitis--a poorly understood entity.

Pouchitis is an increasing drawback to patients who undergo ileal pouch-anal anastomosis for ulcerative colitis; complication overshadows the overall good functional results of this sphincter-saving operation. There is a need for cooperative, multicenter, and longitudinal studies of patients undergoing ileal pouch-anal anastomosis, to unravel the etiology and pathophysiology of pouchitis. Because of the absence of a mucosal inflammation before pouch construction, patients operated on for familial adenomatous polyposis are the perfect control group. Thus, it may be possible to elucidate and define the sequence that leads to pouchitis, including overgrowth of a colonic type flora, transformation of the histology to an epithelium with colonic features, an altered biochemical milieu in the lumen (volatile fatty acids, secondary bile acids), and changes in mucosal defense mechanisms.