Pouchitis – What’s new in etiology and management

Pouchitis requires a clear clinicopathological definition. There are many conflicting data concerning etiology. It is linked to an initial diagnosis of ulcerative colitis by clinical association and occurrence of extra-alimentary manifestations, histologically and by macrophage types and inflammatory mediators. Evidence for a bacteriological cause comes from response to metronidazole, increased counts of intramucosal bacteria in pouchitis and the possible association of hypochlorhydria. Most studies have, however, shown no specific bacterial pathogen or luminal bacterial count differences in pouches with or without pouchitis. Abnormal fecal bile salt concentrations have been reported. Stasis and evacuation efficiency of the pouch are not associated with pouchitis in most studies. Reduced mucosal bloodflow may be associated perhaps leading to increased permeability to toxins causing activation of interleukin-1, platelet-activating factor (PAF) and tumour necrosis factor (TNF). PAF may be increased in pouchitis. Pouchitis may respond to allopurinol. Volatile short chain fatty acids (VSFA) may be reduced in ileal reservoirs compared with straight ileoanal segments and in pouchitis. The response of pouchitis to administered VSFA is, however, variable. Glutamine administration may help. There is evidence that intraepithelial T lymphocytes are reduced. Crypt cell turnover is higher in colitic than in polypotic pouches. Mucosal morphological changes of villous atrophy and inflammation occur early after relapsing polychondritis and may predict future susceptibility to pouchitis. Early mucosal biopsy appears to have prognostic value. Metronidazole and antibiotics (amoxicillin/potassium clavulanate, ciprofloxacin) may be effective although in a controlled trial of the former there was little advantage over placebo. The results of treatment using VSFA, glutamine, allopurinol sucralfate and anti-inflammatory agents, including aminosalicylic acid (5-ASA) and steroids, is reviewed. Assessment of efficacy is difficult because the definition of pouchitis is not standardized, there may be more than one clinical type and studies may not be controlled. Failure of medical treatment may require surgical defunctioning or removal of the pouch